text:
Trading with the Enemy Act of 1917

The Trading with the Enemy Act (TWEA) of 1917 (, codified at and  et seq.) is a United States federal law, enacted on October 6, 1917, in response to the United States declaration of war on Germany on April 6, 1917. It continues to give the President of the United States the power to oversee or restrict any and all trade between the United States and its enemies in times of war. TWEA was amended in 1933 by the Emergency Banking Act to extend the president’s authority also in peace time. It was amended again in 1977 by the International Emergency Economic Powers Act (IEEPA) to restrict again the application of TWEA only to times of war, while the IEEPA was intended to be used in peace time.

TWEA is sometimes confused with the IEEPA, which grants somewhat broader powers to the President, and which is invoked during states of emergency when the United States is not at war. The IEEPA was passed in an attempt to rein in perceived abuses by the US President of the TWEA by making the powers subject to the National Emergencies Act (NEA). The NEA included a legislative veto to allow Congress to terminate a national emergency with a concurrent resolution. However, the U.S. Supreme Court found such legislative vetoes unconstitutional in Immigration and Naturalization Service v. Chadha. Following the Court's decision, Congress amended the NEA to require a joint resolution.

The law set the basis for sanctions by the United States. As of 2023, Cuba is the only country restricted under TWEA. North Korea was removed from the provisions of TWEA in 2008, although restrictions under IEEPA authority remain in effect.

History
The United States declared war on Germany on April 6, 1917. TWEA was enacted on October 6, 1917 and on October 22, 1917, President Woodrow Wilson by Executive Order 2729-A created the Office of Alien Property Custodian (APC) under TWEA with power to confiscate property from anyone whose actions might be considered a possible threat to the war effort. Initially, the Custodian confiscated the property of interned natives of Germany and of businesses, such as the Bayer chemical company. On December 7, 1917, the United States declared war on the Austro-Hungarian Empire, the other Central Power.

In 1933, newly-elected President Franklin D. Roosevelt issued Proclamation 2039, which declared a national emergency and imposed a bank holiday. The proclamation cited TWEA (obliquely referenced as the "Act of October 6, 1917") as the basis of his authority. Aware that such action was legally dubious since the United States was not at war, Roosevelt asked Congress to ratify his actions by passing the Emergency Banking Relief Act, which amended TWEA to enable its use during any "period of national emergency declared by the President." President Franklin D. Roosevelt, using these new authorities, issued Executive Order 6102 to limit gold ownership. These restrictions continued until January 1, 1975. The TWEA has been amended several other times.

During and after both World Wars, property frozen by the United States, belonging to neutral or allied nations, was returned and property belonging to enemy nations was continuously confiscated until hostilities ceased. Some of the confiscated enemy property would not be returned later. Agreements to return some or most assets in exchange for seized American assets and reparations for war-damaged American interests by the new governments of the former enemy nations were later concluded. Nations or organizations that were deemed less responsible for starting the wars receive much more favorable treatment. The United States instituted the Italian Enemy Act of 1947 to deal with former  members of the Mussolini regime from  controlling interest in U.S. based businesses under the TWEA Act of 1917.

On December 16, 1950, the United States imposed economic sanctions against North Korea under TWEA, which lasted until 2008.

On May 13, 1966, President Lyndon B. Johnson abolished the Office of Alien Property Custodian by Executive Order 11281, effective June 30 of that year.

On August 15, 1971, President Richard M. Nixon issued Proclamation 4074, which declared a national emergency under TWEA and imposed a 10% ad valorem supplemental duty on all dutiable articles imported into the United States.

Albania
Albania was invaded by the Central Powers during WW1. While the Central Powers occupied Albania, its assets from the areas they occupied were frozen to prevent the Central Powers from using Albanian assets. Because of this policy, once Central Powers occupation ended the sanctions were effectively lifted.

During WW2, Albania was listed in 1941, to prevent its assets from being used first by the invading fascist Italy and then by the invading Nazi Germany, and was delisted in 1946.

Andorra
Andorra remained officially neutral during WW2. However, it was a tiny country between Axis-friendly Spain and the German puppet state Vichy France. Andorra was listed in 1941, to prevent its assets from being used by Nazi Germany and Vichy France, and was delisted in 1946.

Austria
Austria was invaded and annexed by Germany. It was listed in 1941, to prevent its assets from being used by the invading Nazi Germany,  and was delisted in 1946.

Austro-Hungarian Empire
The Austro-Hungarian Empire was sanctioned in 1917 as an enemy state. It continued to be sanctioned until after its defeat and dissolution in 1918 into Austria and Hungary. The United States remained at "war" with the then-nonexistent dissolved country for several years until deciding to ratify peace treaties with Austria and Hungary separately 1921. No actual combat is known to have taken place between the United States and Austria or Hungary after the empire's dissolution and before the ratification of the peace treaties.

Belgium
Belgium's property was frozen in the event the property was from the areas the invading Central Powers occupied during WW1 to prevent the Central Powers from using its assets. If the area was not occupied, the assets were not frozen. Because of this policy, once Central Powers occupation ended the sanctions were effectively lifted.

Belgium was listed again in 1940, to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946.

Bulgaria
Bulgaria was a German and Austro-Hungarian ally during WW1 and some of its property was frozen or confiscated by the United States. The United States and Bulgaria avoided declaring war on each other during WW1.

During WW2 Bulgaria was an axis power and was sanctioned again in 1941. Sanctions were lifted in 1945. In 1963 the government of Bulgaria agreed to accept American claims for lost property and war damages so the Bulgarians were allowed to reclaim the property America seized during WW2.

Cambodia
Cambodia was sanctioned in 1975 as a result of the Vietnam War. Trading With the Enemy Act sanctions were lifted in 1992.

China
China was listed on two occasions. The Republic of China was first listed in 1941 to prevent invading Japan from using Chinese assets during WW2. China was delisted in 1946. After WW2 the People's Republic of China was sanctioned and listed in 1950 for their involvement in the Korean War. After President Richard Nixon's "opening with China" sanctions were lifted in 1975.

Cuba
Following the Cuban missile crisis, the Bay of Pigs invasion, and the nationalization of U.S. property by the Castro regime, the United States imposed sanctions on Cuba in 1963. TWEA sanctions continued throughout the Cold War because the US and Cuba often found themselves on opposite sides in various proxy conflicts throughout Latin America and Africa. The sanctions on Cuba were increased after the Cuban air force killed American protesters who were known to violate Cuban airspace. Cuba is currently the only state still under sanctions under TWEA.

Czechoslovakia
Czechoslovakia was invaded and annexed by Germany. In 1941 it was listed to prevent its assets from being used by the invading Nazi Germany. Czechoslovakia was delisted in 1946. Czechoslovakian assets were held until the government of Czechoslovakia agreed to return assets its German installed occupation government expropriated during WW2. These restrictions were lifted sometime between 1964 and 1967 after an agreement was reached.

Danzig
Danzig was listed in 1941 to prevent its assets from being used by Nazi Germany. Germany was forced to give up the city of Danzig after WWI. As a result of it being a former German city, there was a considerable amount of support for Nazi Germany to re-annex the territory within the mostly ethnic German Free City of Danzig. The annexation of Danzig happened early in WWII. Sanctions were continued until Danzig ceased to exist. Danzig was made part of Poland and renamed Gdańsk. Danzig's German inhabitants were expelled to Germany as part of the Soviet proposal to prevent the German diaspora outside German borders after WW1 from helping start another world war by requesting annexation.

Denmark
Denmark was listed in 1940 to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946.

East Germany
East Germany, or eastern Germany before 1949, and East Berlin-origin assets were held until the government of East German agreed to return assets the Nazi German government expropriated during WW2. These restrictions were lifted sometime between 1964 and 1967 after an agreement was reached.

Estonia
Estonia was listed in 1940, to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946. Estonian assets were held until the government of Estonia agreed to return assets its German-installed occupation government expropriated during WW2. These restrictions were lifted sometime between 1964 and 1967 after an agreement was reached.

Finland
Finland was invaded in 1939 by the Soviet Union. As a result of this, it allied itself with Germany against the Soviet Union during most of World War 2. It was consequently sanctioned in 1941. Finland was considered an ally of an enemy under TWTEA until the Lapland war in which Finland changed sides. Finland would have then been eligible for the classification of "allies or neutrals" and delisted with the rest of that group in 1946.

France
During WW1, France's property was frozen in the event the property was from the areas occupied by the invading Central Powers to prevent the Central Powers from using its assets. If the area was not occupied, the assets were not frozen. Because of this policy, once the Central Powers' occupation ended the sanctions were effectively lifted.

During WW2, France was listed in 1940 to prevent its assets from being used by the invading Nazi Germany. France was delisted in 1946.

Germany
The Empire of Germany was first sanctioned in 1917 for its role in WW1. Germany remained sanctioned until a U.S.-German peace treaty was ratified in 1921.

Nazi Germany was sanctioned again in 1941 for its role in WW2. Sanctions were lifted in 1946 by Executive Order 9788 and the Office of Alien Property created in the Department of Justice. As Germany was judged to have a primary role in starting both world wars, the United States policy was to confiscate and sell off German assets that Germans acquired before 1946. The War Claims Act of 1948 distributed the vested property if a claim could be established.

Greece
Greece was listed in 1941, to prevent assets from being used by the invading Nazi Germany, and was delisted in 1946.

Hong Kong
Hong Kong was listed in 1941, to prevent its assets from being used by invading Japan, and was delisted in 1946.

Haiti
The military government of Haiti led by General Raoul Cedras and affiliated members such as the CIA-created FRAPH, was listed under the International Economic Powers Act (IEPA Act), now with the Trading With the Enemy Act that has its roots in World War I and the EIPA Act during the Cold War between the US and the former Soviet Union. Many members of the Haitian Army who had properties in the US, their properties either frozen or confiscated by the Clinton administration until they agreed to the return of deposed Haitian President Jean-Bertrand Aristide.

Hungary
Hungary was an Axis power and was sanctioned in 1941. Sanctions were lifted in 1945. Hungarian assets were held until the government of Hungary agreed to return assets it expropriated during WW2 and accept claims for war damages caused by Hungary.

Italy
Italy was an axis power until Italy was invaded and Mussolini's government deposed. Italy was sanctioned in 1941. Sanctions were lifted in 1943 after the allies installed a friendly government and it switched sides. Italy accepted an agreement to return expropriated American property and accept claims for war damages so it was allowed to reclaim its seized property.

Japan
In 1940 US President Franklin D. Roosevelt sanctioned Japan to punish it for invading China and French Indochina under the Export Control Act. In 1941, Roosevelt imposed sanctions under TWEA. Some claim that this was the reason for the attack on Pearl Harbor later in 1941. Sanctions were lifted in 1946. Japan was widely unpopular for the surprise attack on Pearl Harbor. Because Japan was the reason for the United States entering World War II, and due to the fact many Americans wanted to stay out of European wars during both wartime periods, Japanese assets that the Japanese acquired before 1946 were confiscated and divested. The War Claims Act of 1948 distributed the vested property if a claim could be established.

Latvia
Latvia was listed in 1940, to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946. Latvian assets were held until the government of Latvia agreed to return assets its German-installed occupation government expropriated during WW2. These restrictions were lifted sometime between 1964 and 1967 after an agreement was reached.

Liechtenstein
Liechtenstein was listed in 1941. Liechtenstein was perceived to be on Germany's side by some allies even though it remained neutral. Liechtenstein was delisted in 1946.

Lithuania
Lithuania was listed in 1940, to prevent assets from being used by the invading Nazi Germany, and was delisted in 1946. Lithuanian assets were held until the government of Lithuania agreed to return assets its German-installed occupation government expropriated during WW2. These restrictions were lifted sometime between 1964 and 1967 after an agreement was reached.

Luxembourg
Luxembourg was listed in 1940, to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946.

Monaco
Monaco was listed in 1940, to prevent its assets from being used by the invading Nazi Germany, and was delisted in 1946.

Montenegro
Montenegro was invaded by the central powers during WWI. While the central powers occupied Montenegro, its assets from the areas they occupied were frozen to prevent the central powers from using Montenegrin assets. Because of this policy, once the Central Powers' occupation ended the sanctions were effectively lifted.

North Korea
North Korea was sanctioned in 1950 for aggression in the Korean War. The war is still officially in effect, with no peace treaty signed, and the sanctions has been kept due to North Korean terrorism, nuclear proliferation, and continued aggression toward the United States. Trading with the Enemy Act sanctions were lifted in 2008 in response to North Korea's steps toward nuclear disarmament and commitments to continue dismantling its nuclear weapons program. However, North Korea later developed and tested several more nuclear weapons, indicating that it was lying. North Korea's designation was grandfathered from an old version of the law that allowed it to be used absent a declaration of war. Because there is no declaration of war between the United States and North Korea, TWEA sanctions cannot be reapplied, but it was re-sanctioned for reneging on its commitments through the IEEPA, along with other laws, and through UN Security Council resolutions.

North Vietnam
North Vietnam was sanctioned in 1964 during the Vietnam War. Sanctions were continued until North Vietnam ceased to exist and were inherited by the Socialist Republic of Vietnam.

Norway
Norway was listed in 1940 to prevent its assets from being used by the invading Nazi Germany. Norway was delisted in 1946.

Ottoman Empire
The Ottoman Empire was in the Central Powers, an ally of the German Empire, Austria-Hungary and the Kingdom of Bulgaria, which was sanctioned alongside its allies in 1917 with the act, though entering the war later on. The Ottoman Empire and the United States are not known to have fought each other during the war, except for smaller-scaled naval conflicts and bombardments. And little, if any, property was seized from Ottomans as the Ottoman Empire had few resources to be seized that would contribute to the war and economic effort within the United States.

It was judged by the Office of the Alien Property Custodian that seizing the small amount of non-war related Ottoman property that was present in the United States at that time was counter-productive and would later on likely invite the Ottoman Empire onto seizing a larger amount of American property back as in-advance. Thus, the United States didn't want to provoke the Ottomans in such a way that would result in them possibly targeting US affiliates, companies, property and citizens living within the lands & areas they controlled in many ways, and prompt unnecessary mutual declarations of war.

They remained sanctioned even after their defeat by signing the Mudros Armistice in 1918 until their dissolution with the later-to-be revoked Peace Treaty of Sevrés in 1921 when the sanctions were no longer in effect.

The Americans were not going to be directly involved in the Turkish War of Independence which would follow after the signing of Sevrés, nor implement any official sanctions but would support Ententé and Greek forces. Although not officially, a significant portion of the American Congress would later go on to criticise and proclaim the Lausanne Declaration Treaty that would follow after the independence war as invalid, rejecting it by still supporting the post-European and colonial claims on Turkish lands in the Balkans and the Anatoli.

These rejections would later be disregarded, and the United States of America formally established normal & friendly relations with the newly established modern, and more Western-sided Turkish Republic in 1927.

Thus, the new Republic of Turkey was not affected by any American or Allied sanctions anymore, either shortly after the end of the Independence War and the signing of the Lausanne Treaty or during WWII.

Poland
Poland was listed in 1941 to prevent its assets from being used by the invading Nazi Germany. Poland was delisted in 1946.

Portugal
Portugal was listed in 1941. Portugal was a British ally; however, it was officially neutral as part of an allied strategy to avoid costly and pyrrhic military commitments to defend the Iberian peninsula during WW2. Spain would have likely declared war on the Axis side if Portugal entered on the Allied side, opening a large and unnecessary front. While neutral, it traded raw materials used in military production with Germany, though it gave much more assistance and trade to the Allies than the Axis. Portugal was delisted in 1948.

Romania
Romania was invaded by the central powers during World War I. While the central powers occupied Romania, its assets from the areas they occupied were frozen to prevent the central powers from using Romanian assets. Because of this policy, the sanctions were effectively lifted once the Central Powers' occupation ended.

In World War II Romania was an Axis power and sanctioned in 1940. Sanctions were lifted in 1945. Romanian assets were held until the government of Romania agreed to return assets its government expropriated during World War II and accept claims for war damage caused by Romania.

Romania has a long history of being misspelled by previous members of the government of the United States. Rumania and Roumania are common misspellings used in government documents.

Russia
The Russian Empire's property was frozen in the event the property was from the areas the invading Central Powers occupied during WW1 to prevent the Central Powers from using Russian assets. If the area was not occupied, the assets were not frozen. Because of this policy, once the Central Powers' occupation ended the sanctions were effectively lifted.

San Marino
San Marino was listed in 1941. San Marino was perceived to be part of the Axis, though it remained neutral. San Marino was delisted in 1946.

Serbia
Serbia was invaded by the central powers during World War I. While the central powers occupied Serbia, its assets from the areas they occupied were frozen to prevent the central powers from using Serb assets. Because of this policy, once the Central Powers' occupation ended the sanctions were effectively lifted.

Spain
Spain was listed in 1941 for aiding the Axis though officially remaining neutral. Spain was delisted in 1946.

Sweden
Sweden was listed in 1941. While Sweden was officially neutral, it aided both sides during WWII to avoid being at war with either. Sweden was delisted in 1946.

Switzerland
Switzerland was listed in 1941. Although neutral during WWII, it engaged in combat against both sides for infringing on its airspace or territory. Switzerland was delisted in 1946.

Thailand
Thailand was sanctioned in 1941. Thailand was invaded by the Japanese and as a negotiated settlement to the conflict, they became a Japanese ally during WW2. After Japan was defeated, Thailand's subsequent prime minister said the previous government didn't get a valid declaration of war and the previous prime minister's unilateral declaration was null and void. The Office of Alien Property considered Thailand enemy-occupied instead of an enemy power so it was delisted in 1946 and eligible to get its property back.

The Netherlands
The Netherlands was listed in 1940 to prevent its assets from being used by the invading Nazi Germany. The Netherlands was delisted in 1946.

Union of Soviet Socialist Republics
The Soviet Union was sanctioned several times under this act, though for a relatively short period. It was first listed in 1941 to prevent assets from being used by the invading Nazi Germany and other invading axis powers. The Soviet Union was delisted in 1946. Later it was sanctioned during four brief periods from 1972 to 1976 when other Presidential economic powers lapsed due to not being renewed by Congress during the Cold War.

United States
Franklin D. Roosevelt used the Trading with the Enemy Act to shut down financial institutions and declare a "bank holiday" to prevent runs on the banks during the Great Depression in 1933. It was also used to outlaw most ownership of gold in an attempt to prop up the gold-backed dollar. The gold ownership ban was lifted by congressional amendment and gold was no longer used to back printed dollars.

In 1968 Lyndon Johnson used the law to restrict capital exports.

In 1971 Nixon used the TWEA for currency manipulation in an attempt to boost US exports.

In 1982 the United States Treasury Department announced the termination of the Presidential Proclamations and executive orders for the emergencies relating to the 1933 Great Depression ending all domestically oriented TWEA related programs.

Vietnam
The Socialist Republic of Vietnam was sanctioned in 1975 as a result of the Vietnam War. TWEA sanctions were lifted in 1994.

Yugoslavia
Yugoslavia was listed in 1941 to prevent assets from being used by the invading Nazi Germany. Yugoslavia was delisted in 1946.

title: Trading with the Enemy Act of 1917


text:
User:Dany~enwiki

I live in Buenos Aires.

Here are my hobbies:
 * read
 * watch movies
 * program in Java

Write me: mailto:dany@here.com

Read the news: http://www.clarin.com.ar

EAI Home Page

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User:Dany~enwiki


text:
User talk:Daniel C. Boyer/Archive 3

 * "The only reason it even exists is because Daniel Boyer himself created it."

What? Didn't you read my history? Lots of users have redirects from the article namespace to the user namespace. Apparently once upon a time the user namespace didn't exist, so that's probably why in this case. It was me who changed it from an unremarkable redirect, to a real article. My reasons were as follows.

Articles about his works existed at that stage. I'm pretty sure they'd been listed on VFD, but the consensus was to keep them. Those articles linked to Daniel C. Boyer, which at that stage was just a redirect. I thought that was a bizarre sitation, and that if his works were allowed clearly he should be too. I researched Daniel's importance, and decided for myself that he was important enough to be included. I made a case (now recorded in /Archive 1), and publicised my intentions on Village pump. Since this was only a simple editorial decision on my part, you could say that I was being extremely timid in asking everyone if it's okay. Very un-wiki of me. There wasn't much interest, so I did it. A while later, Anthere came asking about including Daniel on the French wiki. A few more people said they were fine with inclusion, so it seemed to me that I'd probably done the right thing.

Then it became clear that Daniel had been inserting his name and works into random articles. After this was pointed out and publicised by Daniel Quinlan, community opinion on this issue went from indifference or acceptance to what we see now -- a significant number of editors hell-bent on the destruction of anything Boyer-related. Maybe I'm confusing correlation with cause, or maybe what I suspect is true: Wikipedians can be a vindictive bunch.

-- Tim Starling 07:57, Jul 31, 2003 (UTC)

 * Or they may be keen on keeping the encyclopedia intact when it becomes obvious that some Wikipedians edit it in a way that is blatantly contrary to its principles. Yes there has been some over-reacting (like my comments on Current disputes over articles). That doesn't change the facts, though.
 * I'm moving some related discussion from the village pump to this page to keep things in one place. Kosebamse 10:08, 31 Jul 2003 (UTC)

 * user:/bio -> Talk:Daniel C. Boyer/move to user:

 * suggestion of seperate namespace/project -> Talk:Daniel C. Boyer/move to user:

title: User talk:Daniel C. Boyer/Archive 3


text:
User talk:Dany~enwiki

This page is really lame! --Travis

 * You're really lame! --Dany

 * table||table||

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Dany. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Dany~enwiki that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name. If you think you might own all of the accounts with this name and this message is in error, please visit Special:MergeAccount to check and attach all of your accounts to prevent them from being renamed.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:20, 19 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 11:57, 22 April 2015 (UTC)

title: User talk:Dany~enwiki


text:
Talk:Belladonna lily

This is probably the weirdest software bug I've seen on Wikipedia, and that's saying something. :)

I was going over this article preparing to delete it because it was listed on VfD over a week. I see in the history that it purports to have been created by IP# 209.98.3.203, which is impossible. That is my IP address, it is static and I have had it continuously for over a year (longer than I've been on Wikipedia). And I did not create the article.

However, about the same time as the articles creation, I was working on fixing up another article, Hippeastrum, which originally contained (I think) the exact same text as this one. (Except for the title, and I didn't create the title either, I'd previously never even heard the term "belladonna lily.")

Is this related to the "edit conflict" problems I've seen mentioned in passing?

Hephaestos 17:35, 31 Jul 2003 (UTC)

 * Might it not be related to the way "Moving" is implemented (it's sort of misnamed if I understand it): When someone "moves" Hippeastrum -> Belladonna lily, what actually happens is the old page (which you created) is renamed Belladonna lily, and a new page called "Hippeastrum" is created with a redirect on it. So you wind up "credited" with creating a page whose name you've never heard of... -- Someone else 17:42, 31 Jul 2003 (UTC)

 * Aha. So if someone moved "Hippeastrum" to "Belladonna lily" while I was editing "Hippeastrum," that would do it?  Makes a little more sense now I guess. - Hephaestos 17:47, 31 Jul 2003 (UTC)

 * That's my guess. I'm often amazed at the (new) titles on articles, discovering I've edited them only by checking the history. -- Someone else 17:49, 31 Jul 2003 (UTC)

 * Although that really doesn't explain the fourth edit to belladonna lily, which is also credited to my IP, and which I didn't make either. Hmm. - Hephaestos 18:02, 31 Jul 2003 (UTC)

 * Might it not have been moved after your last edit? Then you would only have seen the original name, and yet the page you edited would now be named "Belladonna lily"? -- Someone else 18:05, 31 Jul 2003 (UTC)

title: Talk:Belladonna lily


text:
Markup

Markup or mark-up can refer to:

 * Markup language, a standardized set of notations used to annotate a plain-text document's content to give information regarding the structure of the text or instructions for how it is to be displayed
 * Lightweight markup language, notation that adds basic markup to a client
 * Markup rule in economics, a formula for the ratio of a monopolist's chosen price to its marginal cost
 * Markup (business) a term in retail business describing the increase in the price of goods to cover expenses and create a profit margin
 * Markup (legislation), the process to amend bills
 * The Markup, American nonprofit organization publishing data-driven journalism

title: Markup


text:
User:Pseudometric

Richard E. Silverman

dance, music, math, computing — www.qoxp.net

title: User:Pseudometric


text:
User:Ozuma~enwiki

graduate student, majoring in physics, Japanese.

habitat: /.-J ( http://slashdot.jp/~ozuma/ )

title: User:Ozuma~enwiki


text: User talk:130.76.32.15

title: User talk:130.76.32.15


text:
Richard Dyer-Bennet

Richard Dyer-Bennet (6 October 1913 in Leicester, England – 14 December 1991 in Monterey, Massachusetts) was an English-born American folk singer (or his own preferred term, "minstrel"), recording artist, and voice teacher.

Early life
He was born on 6 October 1913 in Leicester, England, as the eldest son of Miriam Wolcott Clapp and Richard Stewart Dyer-Bennet (1886–1983), a Major in the Leicester Regiment who was wounded twice while fighting in World War I. His paternal grandfather was Frederick Stewart Hotham Dyer-Bennet (a grandson of Sir Thomas Swinnerton Dyer, 9th Baronet). Dyer-Bennet grew up in Germany, Canada and California. He studied voice with Gertrude Wheeler Beckman and Sven Scholander.

The meeting with Scholander had a profound effect on Dyer-Bennet, who later recalled:

"He looked straight at me and spun tale after tale as though singing out of his own life. He sang of soldiers, sailors, young lovers; he sang dialogues between mother and daughter, altercations between birds and animals, descriptions of mountain and countryside. A pageant of the ages seemed to pass before my eyes, and it was all evoked by the husky voice of this old man and by his simple but exactly appropriate accompaniments on the lute."

Career
His first album released included the song, The Lonesome Valley, used for many years to sign off the Midnight Special on WFMT each Saturday night. A favorite interview of Studs Terkel.

He had a stroke in 1972 paralyzing his left side and he stopped giving concerts.

Legacy
During his peak performance years, he gave 50 concerts a year. He recorded extensively for many labels, and eventually founded his own, Dyer-Bennet Records, and recorded in his own living room. The albums he recorded on his own label have been re-released on CD by Smithsonian Folkways. The CD Richard Dyer-Bennet 1 includes a biographical essay written by Dyer-Bennet's daughter, Bonnie, which highlights his progressive politics and his battle with a debilitating stroke in later life (he taught himself to play harp one-handed so that he could continue to perform and teach). A biography – Richard Dyer-Bennet: The Last Minstrel – by Paul O Jenkins was published in December 2009 by the University Press of Mississippi. The book chronicles Dyer-Bennet's eventful life and includes a foreword by his daughter.

Personal life
In 1936, Dyer-Bennet married Elizabeth Hoar Pepper. They divorced in 1941. He married Melvene Ipcar in 1942, they had two daughters Brooke and Bonnie.

He was heir presumptive of the Dyer baronets from 1983 until his death. He died of cancer on 14 December 1991 at his home in Monterey, Massachusetts.

Discography

 * Dyer-Bennet Records releases
 * 1949: Richard Dyer-Bennet: Twentieth Century Minstrel (Decca DLP 5046)
 * 1952: Folk Songs (Remington REP-1)
 * 1955: Richard Dyer-Bennet 1
 * 1956: Richard Dyer-Bennet 2
 * 1956: Richard Dyer-Bennet 3
 * 1957: Richard Dyer-Bennet 4
 * 1958: Richard Dyer-Bennet 5: Requests
 * 1958: Richard Dyer-Bennet 6: Songs With Young People in Mind
 * 1958: Richard Dyer-Bennet 7: Beethoven Scottish and Irish Songs
 * 1959: Richard Dyer-Bennet 8: Gems of Minstrelsy
 * 1960: Richard Dyer-Bennet 9
 * 1962: Richard Dyer-Bennet 10
 * 1962: ''A Richard Dyer-Bennet Concert (Stinson Records)
 * 1962: Mark Twain's 1601
 * 1962: Richard Dyer-Bennet 11: Stephen Foster Songs
 * 1964: Richard Dyer-Bennet 12: Songs of Ships, Seafaring Men, Watery Graves...and One Edible Rat
 * 1964: Richard Dyer-Bennet 13: Stories and Songs for Children and Their Parents
 * Folkways Records releases
 * 1967: The Asch Recordings, 1939 to 1945 – Vol. 2 (Folkways Records)
 * All the Dyer-Bennet Records releases have been re-released by Smithsonian Folkways.

Videography

 * 1980:

title: Richard Dyer-Bennet


text:
Talk:Richard Dyer-Bennet

Untitled
In case anybody wonders -- he's my uncle. But I don't benefit financially from his recordings, and I really don't think there's any doubt he's a big enough figure to deserve inclusion here.

Dd-b 17:51, 31 Jul 2003 (UTC)

Can anybody confirm that The Asch Recordings, 1939 to 1945 - Vol. 2 actually contains anything of Dick's? The listings I've found online so far seem to list it as entirely Woody Guthrie content. Dd-b (talk) 01:13, 20 September 2009 (UTC)

 * Yes. It's a little confusing because there are two Folkways releases called "The Asch Recordings, Volume 2". One, as you say, is a Woody Guthrie collection; the other is collection of various Asch recordings, one of which is Dyer-Bennet singing "Two Maidens Went Milking One Day". You can see the details here. --Camembert (talk) 00:21, 13 April 2010 (UTC)

Is That All There Is?
Can no one add to this pitiful biography of one of the great folk singers of the 20th century? 68.104.199.181 (talk) 00:07, 25 July 2013 (UTC)
 * Exactly. I'm looking right now at a free image of him performing in the early 1960s (published at the time without a copyright notice), not terribly high-res, but it shows him performing.  As I'm reading a "biography" consisting of half-assed, half-random statements seemingly slapped together, it's probably not worth the bother to scan it and therefore provide more fodder for the puffery corps lurking about on here.  Feel free to let me know if you believe I'm in the wrong. RadioKAOS / Talk to me, Billy / Transmissions  04:20, 30 August 2016 (UTC)

title: Talk:Richard Dyer-Bennet


text:
Baker–Campbell–Hausdorff formula

In mathematics, the Baker–Campbell–Hausdorff formula gives the value of $$Z$$ that solves the equation $$e^X e^Y = e^Z$$ for possibly noncommutative $X$ and $Y$ in the Lie algebra of a Lie group. There are various ways of writing the formula, but all ultimately yield an expression for $$Z$$ in Lie algebraic terms, that is, as a formal series (not necessarily convergent) in $$X$$ and $$Y$$ and iterated commutators thereof. The first few terms of this series are: $$Z = X + Y + \frac{1}{2} [X,Y] + \frac{1}{12} [X,[X,Y]] - \frac{1}{12} [Y,[X,Y]] + \cdots\,,$$ where "$$\cdots$$" indicates terms involving higher commutators of $$X$$ and $$Y$$. If $$X$$ and $$Y$$ are sufficiently small elements of the Lie algebra $$\mathfrak g$$ of a Lie group $$G$$, the series is convergent. Meanwhile, every element $$g$$ sufficiently close to the identity in $$G$$ can be expressed as $$g = e^X$$ for a small $$X$$ in $$\mathfrak g$$. Thus, we can say that near the identity the group multiplication in $$G$$—written as $$e^X e^Y = e^Z$$—can be expressed in purely Lie algebraic terms. The Baker–Campbell–Hausdorff formula can be used to give comparatively simple proofs of deep results in the Lie group–Lie algebra correspondence.

If $$X$$ and $$Y$$ are sufficiently small $$n \times n$$ matrices, then $$Z$$ can be computed as the logarithm of $$e^X e^Y$$, where the exponentials and the logarithm can be computed as power series. The point of the Baker–Campbell–Hausdorff formula is then the highly nonobvious claim that $$Z := \log \left(e^X e^Y\right)$$ can be expressed as a series in repeated commutators of $$X$$ and $$Y$$.

Modern expositions of the formula can be found in, among other places, the books of Rossmann and Hall.

History
The formula is named after Henry Frederick Baker, John Edward Campbell, and Felix Hausdorff who stated its qualitative form, i.e. that only commutators and commutators of commutators, ad infinitum, are needed to express the solution. An earlier statement of the form was adumbrated by Friedrich Schur in 1890 where a convergent power series is given, with terms recursively defined. This qualitative form is what is used in the most important applications, such as the relatively accessible proofs of the Lie correspondence and in quantum field theory. Following Schur, it was noted in print by Campbell (1897); elaborated by Henri Poincaré (1899) and Baker (1902); and systematized geometrically, and linked to the Jacobi identity by Hausdorff (1906). The first actual explicit formula, with all numerical coefficients, is due to Eugene Dynkin (1947). The history of the formula is described in detail in the article of Achilles and Bonfiglioli and in the book of Bonfiglioli and Fulci.

Explicit forms
For many purposes, it is only necessary to know that an expansion for $$Z$$ in terms of iterated commutators of $$X$$ and $$Y$$ exists; the exact coefficients are often irrelevant. (See, for example, the discussion of the relationship between Lie group and Lie algebra homomorphisms in Section 5.2 of Hall's book, where the precise coefficients play no role in the argument.) A remarkably direct existence proof was given by Martin Eichler, see also the "Existence results" section below.

In other cases, one may need detailed information about $$Z$$ and it is therefore desirable to compute $$Z$$ as explicitly as possible. Numerous formulas exist; we will describe two of the main ones (Dynkin's formula and the integral formula of Poincaré) in this section.

Dynkin's formula
Let G be a Lie group with Lie algebra $$\mathfrak g$$. Let $$\exp : \mathfrak g \to G $$ be the exponential map. The following general combinatorial formula was introduced by Eugene Dynkin (1947), $$\log(\exp X\exp Y) = \sum_{n = 1}^\infty\frac {(-1)^{n-1}}{n} \sum_{\begin{smallmatrix} r_1 + s_1 > 0 \\ \vdots \\ r_n + s_n > 0 \end{smallmatrix}} \frac{[ X^{r_1} Y^{s_1} X^{r_2} Y^{s_2} \dotsm X^{r_n} Y^{s_n} ]}{\left(\sum_{j = 1}^n (r_j + s_j)\right) \cdot \prod_{i = 1}^n r_i! s_i!}, $$ where the sum is performed over all nonnegative values of $$s_i$$ and $$r_i$$, and the following notation has been used: $$ [ X^{r_1} Y^{s_1} \dotsm X^{r_n} Y^{s_n} ] = [ \underbrace{X,[X,\dotsm[X}_{r_1} ,[ \underbrace{Y,[Y,\dotsm[Y}_{s_1} ,\,\dotsm\, [ \underbrace{X,[X,\dotsm[X}_{r_n} ,[ \underbrace{Y,[Y,\dotsm Y}_{s_n} ]]\dotsm]]$$ with the understanding that $[X] := X$.

The series is not convergent in general; it is convergent (and the stated formula is valid) for all sufficiently small $$X$$ and $$Y$$. Since $[A, A] = 0$, the term is zero if $$s_n > 1$$ or if $$s_n = 0$$ and $$r_n > 1$$.

The first few terms are well-known, with all higher-order terms involving $[X,Y]$ and commutator nestings thereof (thus in the Lie algebra):

The above lists all summands of order 6 or lower (i.e. those containing 6 or fewer $X$'s and $Y$'s). The $X ↔ Y$ (anti-)/symmetry in alternating orders of the expansion, follows from $Z(Y, X) = −Z(−X, −Y)$. A complete elementary proof of this formula can be found in the article on the derivative of the exponential map.

An integral formula
There are numerous other expressions for $$Z$$, many of which are used in the physics literature. A popular integral formula is $$\log\left(e^X e^Y\right) = X + \left ( \int_0^1 \psi \left ( e^{\operatorname{ad} _X} ~ e^{t \operatorname{ad} _ Y}\right ) dt \right) Y, $$ involving the generating function for the Bernoulli numbers, $$ \psi(x) ~\stackrel{\text{def}}{=} ~ \frac{x \log x}{x-1}= 1- \sum^\infty_{n=1} {(1-x)^n \over n (n+1)} ~, $$ utilized by Poincaré and Hausdorff.

Matrix Lie group illustration
For a matrix Lie group $$G \sub \mbox{GL}(n,\mathbb{R})$$ the Lie algebra is the tangent space of the identity I, and the commutator is simply $[X, Y] = XY − YX$; the exponential map is the standard exponential map of matrices, $$\exp X = e^X = \sum_{n=0}^\infty {\frac{X^n}{n!}}.$$

When one solves for Z in $$e^Z = e^X e^Y,$$ using the series expansions for $exp$ and $log$ one obtains a simpler formula: $$ Z = \sum_{n>0} \frac{(-1)^{n-1}}{n} \sum_{\stackrel{r_i+s_i > 0}{1 \le i \le n}} \frac{X^{r_1}Y^{s_1} \cdots X^{r_n}Y^{s_n}}{r_1!s_1!\cdots r_n!s_n!}, \quad \|X\| + \|Y\| < \log 2, \|Z\| < \log 2.$$ The first, second, third, and fourth order terms are:
 * $$z_1 = X + Y$$
 * $$z_2 = \frac{1}{2} (XY - YX)$$
 * $$z_3 = \frac{1}{12} \left(X^2Y + XY^2 - 2XYX + Y^2X + YX^2 - 2YXY\right)$$
 * $$z_4 = \frac{1}{24} \left(X^2Y^2 - 2XYXY - Y^2X^2 + 2YXYX \right).$$

The formulas for the various $$z_j$$'s is not the Baker–Campbell–Hausdorff formula. Rather, the Baker–Campbell–Hausdorff formula is one of various expressions for $$z_j$$'s in terms of repeated commutators of $$X$$ and $$Y$$. The point is that it is far from obvious that it is possible to express each $$z_j$$ in terms of commutators. (The reader is invited, for example, to verify by direct computation that $$z_3$$ is expressible as a linear combination of the two nontrivial third-order commutators of $$X$$ and $$Y$$, namely $$[X,[X,Y]]$$ and $$[Y,[X,Y]]$$.) The general result that each $$z_j$$ is expressible as a combination of commutators was shown in an elegant, recursive way by Eichler.

A consequence of the Baker–Campbell–Hausdorff formula is the following result about the trace: $$\operatorname{tr} \log \left(e^X e^Y \right) = \operatorname{tr} X + \operatorname{tr} Y.  $$ That is to say, since each $$z_j$$ with $$j\geq 2$$ is expressible as a linear combination of commutators, the trace of each such terms is zero.

Questions of convergence
Suppose $$X$$ and $$Y$$ are the following matrices in the Lie algebra $$\mathfrak{sl}(2;\mathbb C)$$ (the space of $$2\times 2$$ matrices with trace zero): $$X=\begin{pmatrix}0&i\pi\\ i\pi&0\end{pmatrix};\quad Y=\begin{pmatrix}0&1\\ 0&0\end{pmatrix}.$$ Then $$e^X e^Y = \begin{pmatrix}-1&0\\ 0&-1\end{pmatrix}\begin{pmatrix}1&1\\ 0&1\end{pmatrix}=\begin{pmatrix}-1&-1\\ 0&-1\end{pmatrix}.$$ It is then not hard to show that there does not exist a matrix $$Z$$ in $$\operatorname{sl}(2;\mathbb C)$$ with $$e^X e^Y = e^Z$$. (Similar examples may be found in the article of Wei. )

This simple example illustrates that the various versions of the Baker–Campbell–Hausdorff formula, which give expressions for $R$ in terms of iterated Lie-brackets of $C$ and $e^{Z} = e^{X}e^{Y}$, describe formal power series whose convergence is not guaranteed. Thus, if one wants $\|X\| + \|Y\| < log 2, \|Z\| < log 2$ to be an actual element of the Lie algebra containing $Z$ and $X$ (as opposed to a formal power series), one has to assume that $Y$ and $Z$ are small. Thus, the conclusion that the product operation on a Lie group is determined by the Lie algebra is only a local statement. Indeed, the result cannot be global, because globally one can have nonisomorphic Lie groups with isomorphic Lie algebras.

Concretely, if working with a matrix Lie algebra and $$\|\cdot\|$$ is a given submultiplicative matrix norm, convergence is guaranteed if $$\|X\| + \|Y\| < \frac{\ln 2} 2.$$

Special cases
If $$X$$ and $$Y$$ commute, that is $$[X, Y]=0$$, the Baker–Campbell–Hausdorff formula reduces to $$e^X e^Y = e^{X+Y}$$.

Another case assumes that $$[X,Y]$$ commutes with both $$X$$ and $$Y$$, as for the nilpotent Heisenberg group. Then the formula reduces to its first three terms.

Theorem: If $$X$$ and $$Y$$ commute with their commutator, $$[X,[X,Y]] = [Y,[X,Y]] = 0$$, then $$e^X e^Y = e^{X+Y+\frac{1}{2}[X,Y]}$$.

This is the degenerate case used routinely in quantum mechanics, as illustrated below and is sometimes known as the disentangling theorem. In this case, there are no smallness restrictions on $$X$$ and $$Y$$. This result is behind the "exponentiated commutation relations" that enter into the Stone–von Neumann theorem. A simple proof of this identity is given below.

Another useful form of the general formula emphasizes expansion in terms of Y and uses the adjoint mapping notation $$\operatorname{ad}_X(Y)=[X,Y]$$: $$\log(\exp X\exp Y) = X + \frac{\operatorname{ad}_X}{1-e^{-\operatorname{ad}_X}} ~ Y + O\left(Y^2\right) = X + \operatorname{ad}_{X/2} (1 + \coth \operatorname{ad}_{X/2}) ~ Y + O\left(Y^2\right) ,$$ which is evident from the integral formula above. (The coefficients of the nested commutators with a single $$Y$$ are normalized Bernoulli numbers.)

Now assume that the commutator is a multiple of $$Y$$, so that $$[X,Y] = sY$$. Then all iterated commutators will be multiples of $$Y$$, and no quadratic or higher terms in $$Y$$ appear. Thus, the $$O\left(Y^2\right)$$ term above vanishes and we obtain:

Theorem: If $$[X,Y] = sY$$, where $$s$$ is a complex number with $$s \neq 2\pi in$$ for all integers $$n$$, then we have $$e^X e^Y = \exp\left( X+\frac{s}{1-e^{-s}}Y\right).$$

Again, in this case there are no smallness restriction on $$X$$ and $$Y$$. The restriction on $$s$$ guarantees that the expression on the right side makes sense. (When $$s = 0$$ we may interpret $\lim_{s\to 0} s/(1-e^{-s}) = 1$ .) We also obtain a simple "braiding identity": $$e^{X} e^{Y} = e^{\exp (s) Y} e^{X} ,$$ which may be written as an adjoint dilation: $$e^{X} e^{Y} e^{-X} = e^{\exp (s) \, Y} .$$

Existence results
If $$X$$ and $$Y$$ are matrices, one can compute $$Z := \log \left(e^X e^Y\right)$$ using the power series for the exponential and logarithm, with convergence of the series if $$X$$ and $$Y$$ are sufficiently small. It is natural to collect together all terms where the total degree in $$X$$ and $$Y$$ equals a fixed number $$k$$, giving an expression $$z_k$$. (See the section "Matrix Lie group illustration" above for formulas for the first several $$z_k$$'s.) A remarkably direct and concise, recursive proof that each $$z_k$$ is expressible in terms of repeated commutators of $$X$$ and $$Y$$ was given by Martin Eichler.

Alternatively, we can give an existence argument as follows. The Baker–Campbell–Hausdorff formula implies that if $X$ and $Y$ are in some Lie algebra $$\mathfrak g,$$ defined over any field of characteristic 0 like $$\Reals$$ or $$\Complex$$, then $$Z = \log(\exp(X) \exp(Y)),$$ can formally be written as an infinite sum of elements of $$\mathfrak g$$. [This infinite series may or may not converge, so it need not define an actual element $X$ in $$\mathfrak g$$.] For many applications, the mere assurance of the existence of this formal expression is sufficient, and an explicit expression for this infinite sum is not needed. This is for instance the case in the Lorentzian construction of a Lie group representation from a Lie algebra representation. Existence can be seen as follows.

We consider the ring $$S = \RX,Y$$ of all non-commuting formal power series with real coefficients in the non-commuting variables $Y$ and $X$. There is a ring homomorphism from $Y$ to the tensor product of $Z$ with $X$ over $Y$, $$\Delta \colon S \to S \otimes S,$$ called the coproduct, such that $$\Delta(X) = X \otimes 1 + 1 \otimes X$$ and $$\Delta(Y) = Y \otimes 1 + 1 \otimes Y.$$ (The definition of Δ is extended to the other elements of S by requiring R-linearity, multiplicativity and infinite additivity.)

One can then verify the following properties:
 * The map $S$, defined by its standard Taylor series, is a bijection between the set of elements of $S$ with constant term 0 and the set of elements of $S$ with constant term 1; the inverse of exp is log
 * $$r = \exp(s)$$ is grouplike (this means $$\Delta(r) = r\otimes r$$) if and only if s is primitive (this means $$\Delta(s) = s\otimes 1 + 1\otimes s$$).
 * The grouplike elements form a group under multiplication.
 * The primitive elements are exactly the formal infinite sums of elements of the Lie algebra generated by X and Y, where the Lie bracket is given by the commutator $$[U,V] = UV - VU$$. (Friedrichs' theorem )

The existence of the Campbell–Baker–Hausdorff formula can now be seen as follows: The elements X and Y are primitive, so $$\exp(X)$$ and $$\exp(Y)$$ are grouplike; so their product $$\exp(X)\exp(Y)$$ is also grouplike; so its logarithm $$\log(\exp(X)\exp(Y))$$ is primitive; and hence can be written as an infinite sum of elements of the Lie algebra generated by $R$ and $exp$.

The universal enveloping algebra of the free Lie algebra generated by $S$ and $S$ is isomorphic to the algebra of all non-commuting polynomials in $X$ and $Y$. In common with all universal enveloping algebras, it has a natural structure of a Hopf algebra, with a coproduct $X$. The ring $Y$ used above is just a completion of this Hopf algebra.

Zassenhaus formula
A related combinatoric expansion that is useful in dual applications is $$e^{t(X+Y)} = e^{tX}~ e^{tY} ~e^{-\frac{t^2}{2} [X,Y]} ~ e^{\frac{t^3}{6}(2[Y,[X,Y]]+ [X,[X,Y]] )} ~ e^{\frac{-t^4}{24}([[[X,Y],X],X] + 3[[[X,Y],X],Y] + 3[[[X,Y],Y],Y]) } \cdots$$ where the exponents of higher order in $X$ are likewise nested commutators, i.e., homogeneous Lie polynomials. These exponents, $Y$ in $Δ$, follow recursively by application of the above BCH expansion.

As a corollary of this, the Suzuki–Trotter decomposition follows.

The identity (Campbell 1897)
Let $S$ be a matrix Lie group and $t$ its corresponding Lie algebra. Let $C_{n}$ be the linear operator on $exp(−tX) exp(t(X+Y)) = Π_{n} exp(t^{n} C_{n})$ defined by $G$ for some fixed $g$. (The adjoint endomorphism encountered above.) Denote with $ad_{X}$ for fixed $g$ the linear transformation of $ad_{X } Y = [X,Y] = XY − YX$ given by $X ∈ g$.

A standard combinatorial lemma which is utilized in producing the above explicit expansions is given by $$ \operatorname{Ad}_{e^X} = e^{\operatorname{ad}_X}, $$ so, explicitly, $$ \operatorname{Ad}_{e^X}Y = e^{X}Y e^{-X} = e^{\operatorname{ad} _X} Y =Y+\left[X,Y\right]+\frac{1}{2!}[X,[X,Y]]+\frac{1}{3!}[X,[X,[X,Y]]]+\cdots.$$ This is a particularly useful formula which is commonly used to conduct unitary transforms in quantum mechanics. By defining the iterated commutator, $$[(X)^n,Y] \equiv \underbrace{[X,\dotsb[X,[X}_{n \text { times }}, Y]] \dotsb],\quad [(X)^0,Y] \equiv Y,$$ we can write this formula more compactly as, $$e^X Y e^{-X} = \sum_{n=0}^{\infty} \frac{[(X)^n,Y]}{n!}.$$

This formula can be proved by evaluation of the derivative with respect to $Ad_{A}$ of $A ∈ G$, solution of the resulting differential equation and evaluation at $g$, $$\frac{d}{ds}f(s)Y = \frac{d}{ds} \left (e^{sX}Ye^{-sX} \right ) = X e^{sX} Y e^{-sX} - e^{sX}Y e^{-sX}X = \operatorname{ad}_X (e^{sX}Ye^{-sX})$$ or $$ f'(s) = \operatorname{ad}_Xf(s), \qquad f(0) = 1 \qquad \Longrightarrow \qquad f(s) = e^{s \operatorname{ad}_X}.$$

An application of the identity
For $Ad_{A}Y = AYA^{−1}$ central, i.e., commuting with both $X$ and $Y$, $$e^{sX} Y e^{-sX} = Y + s [ X, Y ] ~. $$ Consequently, for $s$, it follows that $$\frac{dg}{ds} = \Bigl( X+ e^{sX} Y e^{-sX}\Bigr) g(s) = (X + Y + s [ X, Y ]) ~g(s) ~, $$ whose solution is $$g(s)= e^{s(X+Y) +\frac{s^2}{2} [ X, Y ] } ~. $$ Taking $$s=1$$ gives one of the special cases of the Baker–Campbell–Hausdorff formula described above: $$e^X e^Y= e^{X+Y +\frac{1}{2} [ X, Y] } ~. $$

More generally, for non-central $f (s)Y ≡ e^{sX} Y e^{−sX}$, the following braiding identity further follows readily, $$e^{X} e^{Y} = e^{(Y+\left[X,Y\right]+\frac{1}{2!}[X,[X,Y]]+\frac{1}{3!}[X,[X,[X,Y]]]+\cdots)} ~e^X.$$

Infinitesimal case
A particularly useful variant of the above is the infinitesimal form. This is commonly written as $$e^{-X} de^X= dX-\frac{1}{2!}\left[X,dX\right]+\frac{1}{3!}[X,[X,dX]]-\frac{1}{4!}[X,[X,[X,dX]]]+\cdots$$ This variation is commonly used to write coordinates and vielbeins as pullbacks of the metric on a Lie group.

For example, writing $$X=X^ie_i$$ for some functions $$X^i$$ and a basis $$e_i$$ for the Lie algebra, one readily computes that $$e^{-X}d e^X= dX^i e_i-\frac{1}{2!} X^i dX^j {f_{ij}}^k e_k + \frac{1}{3!} X^iX^j dX^k {f_{jk}}^l {f_{il}}^m e_m - \cdots ,$$ for $$[e_i,e_j] = {f_{ij}}^k e_k$$ the structure constants of the Lie algebra.

The series can be written more compactly (cf. main article) as $$e^{-X}d e^X = e_i{W^i}_j dX^j,$$ with the infinite series $$W = \sum_{n=0}^\infty \frac{(-1)^n M^n}{(n+1)!} = (I-e^{-M}) M^{-1}.$$ Here, $M$ is a matrix whose matrix elements are $${M_j}^k = X^i {f_{ij}}^k$$.

The usefulness of this expression comes from the fact that the matrix $M$ is a vielbein. Thus, given some map $$N \to G$$ from some manifold $N$ to some manifold $G$, the metric tensor on the manifold $N$ can be written as the pullback of the metric tensor $$B_{mn}$$ on the Lie group $G$, $$g_{ij} = {W_i}^m {W_j}^n B_{mn}.$$ The metric tensor $$B_{mn}$$ on the Lie group is the Cartan metric, the Killing form. For $N$ a (pseudo-)Riemannian manifold, the metric is a (pseudo-)Riemannian metric.

Application in quantum mechanics
A special case of the Baker–Campbell–Hausdorff formula is useful in quantum mechanics and especially quantum optics, where $s = 1$ and $[X,Y]$ are Hilbert space operators, generating the Heisenberg Lie algebra. Specifically, the position and momentum operators in quantum mechanics, usually denoted $$X$$ and $$P$$, satisfy the canonical commutation relation: $$[X,P] = i\hbar I$$ where $$I$$ is the identity operator. It follows that $$X$$ and $$P$$ commute with their commutator. Thus, if we formally applied a special case of the Baker–Campbell–Hausdorff formula (even though $$X$$ and $$P$$ are unbounded operators and not matrices), we would conclude that $$e^{iaX} e^{ibP} = e^{i \left(aX + bP - \frac{ab\hbar}{2}\right)}.$$ This "exponentiated commutation relation" does indeed hold, and forms the basis of the Stone–von Neumann theorem. Further,

A related application is the annihilation and creation operators, $â$ and $g(s) ≡ e^{sX} e^{sY}$. Their commutator $[X,Y]$ is central, that is, it commutes with both $â$ and $X$. As indicated above, the expansion then collapses to the semi-trivial degenerate form: $$ e^{v\hat{a}^\dagger - v^*\hat{a}} = e^{v\hat{a}^\dagger} e^{-v^*\hat{a}} e^{-|v|^{2}/2} ,$$ where $v$ is just a complex number.

This example illustrates the resolution of the displacement operator, $Y$, into exponentials of annihilation and creation operators and scalars.

This degenerate Baker–Campbell–Hausdorff formula then displays the product of two displacement operators as another displacement operator (up to a phase factor), with the resultant displacement equal to the sum of the two displacements, $$ e^{v\hat{a}^\dagger - v^*\hat{a}} e^{u\hat{a}^\dagger - u^*\hat{a}} = e^{(v+u)\hat{a}^\dagger -(v^*+u^*)\hat{a}} e^{(vu^*-uv^*)/2},$$ since the Heisenberg group they provide a representation of is nilpotent. The degenerate Baker–Campbell–Hausdorff formula is frequently used in quantum field theory as well.

title: Baker–Campbell–Hausdorff formula


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Landsknecht

The Landsknechte (singular: Landsknecht, ), also rendered as Landsknechts or Lansquenets, were German mercenaries used in pike and shot formations during the early modern period. Consisting predominantly of pikemen and supporting foot soldiers, their front line was formed by Doppelsöldner ("double-pay men") renowned for their use of Zweihänder and arquebus. They formed the bulk of the Holy Roman Empire's Imperial Army from the late 15th century to the early 17th century, fighting in the Habsburg-Valois wars, the Habsburg-Ottoman wars, and the European wars of religion.

Although prone to mutiny if unpaid and divided within their ranks between Catholics and Lutherans, the Landsknechte were well-armed and experienced warriors, recruitable in large numbers throughout Germany and Austria by the Holy Roman Emperor. This guaranteed both quantity and quality to the Imperial military for a century and a half. At their peak during the reign of Charles V of Habsburg, and under the leadership of notable captains such as Georg von Frundsberg and Nicholas of Salm, the Imperial Landsknechts obtained important successes such as the capture of the French King Francis I at the Battle of Pavia in 1525 and the resistance against the Ottoman Turks led by Suleiman the Magnificent at the Siege of Vienna in 1529, while also being responsible for the Sack of Rome in 1527.

Etymology
The Germanic compound Landsknecht (earlier Lantknecht, without Fugen-"s") combines Land and Knecht to form "servant of the land". The compound Lantknecht was used during the 15th century for bailiffs or court ushers.

The word Landsknecht first appeared in the German language circa 1470 to describe certain troops in the army of Charles, Duke of Burgundy. As early as 1500, the term was morphed into Lanzknecht, referring to the unit's use of the pike as its main weapon.

History

Over the Burgundian Wars, the well-organized and supplied armies of Charles the Bold were defeated again and again by the Swiss Confederation, which wielded an ad hoc militia army. Charles's army lacked esprit de corps because of its composition by feudal lords, mercenaries, and levied gentry. The Swiss army, though poorly organized, were highly motivated, aggressive, and well-trained with their arms. The Swiss pikemen, called Reisläufer, repeatedly defeated and eventually killed Charles, eliminating Burgundy as a European power. Archduke Maximilian, who became co-ruler of Burgundian lands in 1477 by marrying Mary of Burgundy, was greatly influenced by the Swiss victories. When the French contested the inheritance, Maximilian levied a Flemish army and defeated the French in 1479 at the Battle of Guinegate, mixing Swiss-styled square infantry formation and Hussite wagon forts tactics. The dissolution of his levied army at war's end found Maximilian wanting a permanent and organized military force like the Confederation's to protect his domain. The existing Burgundian structure was inadequate to this end, however, and moreover the French wielded a monopoly on the hiring of Reisläufer.

Maximilian began raising the first Landsknecht units in 1486, amassing 6,000–8,000 mercenaries. One of these units he gave to Eitel Friedrich II, Count of Hohenzollern, who trained them with Swiss instructors in Bruges in 1487 to become the "Black Guard" – the first Landsknechte. In 1488, Maximilian organized the Swabian League, creating an army of 12,000 infantry and 1,200 cavalry to deter Bavaria and Bohemia. This is considered to be the first Landsknecht army to be raised in Germany. Maximilian raised a strong army for the Austrian-Hungarian War of 1490, and succeeded in driving the Hungarians out of Austria. The Landsknechte in his army refused to serve after sacking Stuhlweissenburg (now Székesfehérvár, Hungary), citing lack of pay and stopping Maximilian's advance on Buda. To prevent a repeat of Stuhlweissenburg, Maximilian now sought to homogenize the Landsknechte into a fully professional, and mostly Germanic military force.

In the 1490s, the well-trained Landsknechte managed to defeat significantly greater Frisian armies. Paul Dolnstein wrote of the siege of Älvsborg Fortress in July 1502, fighting for the king of Denmark: "We were 1800 Germans, and we were attacked by 15000 Swedish farmers ... we struck most of them dead." After the Battle of Novara in 1513, the Swiss executed the hundreds of German Landsknecht mercenaries they had captured who had fought for the French. At the Battle of Bicocca and the Battle of Marignano (1515), the Landsknecht performed well, defeating the famed Reisläufer.

In 1521, the Spaniards recruited German infantrymen to defend their country against the French because, as they stated "our infantry does not perform as well in its native country as abroad".

The Imperial Landsknechte were instrumental in many of the Emperor's victories, including the decisive Battle of Pavia in 1525. The same year, they also managed to defeat the peasants' revolt in the Empire. At their peak in the early 16th century, the Landsknechte were considered formidable soldiers who were often brave and loyal. However, these qualities may have declined afterward. The Landsknechte were also employed by the Habsburg emperor and the royal Valencian authorities in the suppression of the First Revolt of Espadà of 1526, which took place in the mountains of Espadà, in modern-day Spanish Castelló province (then in the Aragonese Kingdom of Valencia), where thousands of Valencian Muslim fellahs took up arms against the decree of forced conversion issued that very year by the emperor.

They are attested as deployed in the armies of Kings John III of Navarre and successor Henry II of Navarre during their campaigns to reconquer Navarre (1512–1524). In the same context, they are also found fighting on Charles V's side (battle for Hondarribia, 1521–1524) where they performed strongly. They also served in high numbers in the Imperial army during the campaigns of Austria (1532), France (1542), Germanic Reformed League (1547) and in of all the Italian wars. Others also fought on the Habsburg-Ottoman frontier.

The army of the Holy Roman Emperor defeated the French army in Italy, but funds were not available to pay the soldiers. The 34,000 Imperial troops mutinied and forced their commander, Charles III, Duke of Bourbon, to lead them towards Rome. The Sack of Rome in 1527 was executed by some 6,000 Spaniards under the Duke, 14,000 Landsknechte under Georg von Frundsberg, some Italian infantry and some cavalry.

Terence McIntosh comments that the expansionist, aggressive policy pursued by Maximilian I and Charles V at the inception of the early modern German nation (although not to further the aims specific to the German nation per se), mainly relying on German manpower as well as utilizing fearsome Landsknecht and other mercenaries (with the Battle of Pavia and atrocities like the Sack of Rome being associated with them), would affect the way neighbours viewed the German polity, although in the longue durée, Germany tended to be at peace.

From the 1560s on, after the death of Frundsberg, the reputation of the Landsknechte steadily decreased. In the French Wars of Religion and the Eighty Years War, their bravery and discipline came under criticism, and the Spanish elements of the army of Flanders regularly deprecated the battlefield usefulness of the Landsknechte, somewhat unfairly. Their status also suffered from the rising reputation of the dreaded Spanish tercios who, however, were far less abundant and more expensive to train. When serving in southern Europe, Landsknechte were still considered elite troops. In the army of the Dutch rebels, many German mercenaries were hired but were forced to give up some Landsknecht traditions in order to increase their discipline in river crossing and their naval fighting abilities. Increasing ill-discipline within the ranks saw them replaced with an improved system of raising a German army, the Kaiserlicher Fussknecht, which was far less reliant on mercenaries.

Organization and recruitment

The Landsknechte, often recruited from South Germany, came from a society with exploding population growth, increasing unemployment, diverse cultural factors and depleting hierarchical structure (unlike the tightly organized society of the Swiss). In addition to dispossessed craftmen and peasants, there were burghers, aristocrats and runaway serfs as well. They were also used to freedom of carrying weapons. The result was that soldiers leaned towards a libertine (and also brutal) lifestyle. Thus, the role of the regiment, leadership by example (commanders tended to dismount to fight with the troops) and harsh discipline (involving capital punishment) were emphasized to compensate.

As with the Reisläufer, a regiment (a typical Landsknecht regiment consisted of 4,000 men) of Landsknechte was raised by a lord with a letter patent (Bestallungsbrief) that named the unit colonel (Obrist). This document laid out the size and structure of the unit, the pay of its men, and contained its Articles of War (Artikelsbriefe). Upon accepting the commission and securing funding, either through a bank loan or a grant from the lord, the colonel assembled his chain of command. His captains, once appointed, would then go to a locality he knew with drummers and fifers. Recruits gathered at a specified place and time for the muster. There, they would parade under an arch and be inspected by the colonel and his captains, then be paid their first months' salary. The colonel next read the Bestallungsbrief in full to the soldiers, who then swore oaths of allegiance to cause, officers, and the Emperor. This ceremony also saw the appointing of the unit staff and its standard bearers, or Fähnriche (ensigns), who swore to never lose the standard.

The colonel was the highest–ranking officer in a Landsknecht in a regiment, but if his force contained more than one regiment he could become a Generalobrist. If it contained cavalry and artillery in addition to its infantry, then he could be a Feldobrist or Generalfeldobrist. The regiment would be commanded by a lieutenant colonel in the colonel's stead. The regiment itself was formed by ten Fähnlein, equivalent to a company and commanded by a captain. A Fähnlein was made up by 400 men, including 100 veterans. Rotten, equivalent to a platoon, were the building blocks of the Fähnlein and contained either ten ordinary Landsknechte or six Doppelsöldner, led by a Rottmeister elected by his unit. In totality, the regiment averaged 4,000 men; ten Fähnlein, containing 40 Rotten. Unit sergeant majors, called Feldweibel, were tasked with training drill and formation. The regimental sergeant major, Oberster-Feldweibel was responsible for drill on the battlefield. Rotten sergeants, Weibel, were charged with ensuring discipline and relaying liaisons between enlisted men and their officers. One of these men, the Gemeinweibel, was the spokesman for the men and was elected monthly.

According to Imperial law, a colonel could have a staff of 22 officers but in practice this depended on the colonel's wealth. Included in that staff were a chaplain, a scribe, a doctor, a scout, his personal quartermaster and ensign, a drummer and fifer, and a bodyguard (Trabanten) of eight men. Captains also had a staff that included much of the same, but with additional musicians and two Doppelsöldner to protect him. A provost marshal and Schultheiss were appointed by the colonel to maintain military discipline and to prosecute the Artikelsbriefe respectively. The provost was unimpeachable, and feared. Harsh punishments could be expected for offenses such as mutiny or drunkenness on duty. A provost had a retinue of a jailer, bailiff, and executioner (Freimann).

Equipment

Just like the Reisläufer, Landsknecht formations consisted of men trained and armed with pikes, halberds, and swords. 300 men of a Fähnlein would be armed with a pike, though a Landsknecht's pike was generally shorter than a Reisläufer's at about 4.2 m. Experienced and well-equipped soldiers, receiving double a normal Landsknecht's pay and getting the title Doppelsöldner, made up a quarter of each Fähnlein. 50 of these men were armed with a halberd or with a 66 in two-handed sword called a Zweihänder while another fifty were arquebusiers or crossbowmen. The focus on firearms, rather than crossbows, as ordained by Maximilian, was where they were different from the Swiss. Maximilian abolished the crossbow in military use in 1517 (although other countries continued to use them). Most Landsknechte, regardless of primary weapon, carried a short sword called a Katzbalger for close combat. By the end of the 16th century, however, the number of pikemen in a Fähnlein had diminished to around 200.

Tactics
They also copied the Swiss in tactics. Landsknechte fought in a pike square they called the gevierte Ordnung, forty to sixty men deep. Doppelsöldnern made up the formation's first two ranks. Then came the ensigns, and then the squares themselves. Pikemen, supported by halberdiers, formed the square while swordsmen made up their front and rear. The most experienced soldiers were located at the back of the formation and arquebusiers were placed on its flanks. In the attack, a band of soldiers called a forlorn hope preceded the pike square to break enemy pikes.

The pikemen were supported by halberdiers, who would rush a gap in an opposing line, a tactic also copied from the Swiss. As their solidarity grew, commanders emphasized finesse and timing, rather than the head-down battering charge of the Swiss.

As the Landsknechte's fighting techniques were developed, they no longer preferred fighting along a straight line (as exercised by even the Swiss until the end of the fifteenth century), but leaned towards a circle-wise movement that enhanced the use of the space around the combatant and allowed them to attack the opponents from different angles. The circle-wise formation described by Jean Molinet as the "snail" would become the hallmark of Landsknechte's combat. The new types of combat also required the maintenance of a stable bodily equilibrium. Maximilian, an innovator of these types of movements, also saw value in their effects over the maintenance of group discipline (apart from the control of centralized institutions). As Maximilian and his commanders sought to popularize these forms of movements (which only became daily practice at the end of the fifteenth century and gained dominance after Maximilian's death in 1519), he promoted them in tournaments, in fencing and in dancing as well. The courtly festivals became a playground for innovations, foreshadowing developments in military practices.

Camp

The Tross were the camp followers or baggage train who traveled with each Landsknecht unit, carrying military necessities, the food, and the belongings of each soldier and his family. The Tross was made up of women, children and some craftsmen. Women and young boys set up Landsknecht camps, cooked, mended injuries, and dug and cleaned latrines. A Landsknecht was usually forbidden by his Bestallungsbrief from having more than one woman in the baggage train. The Tross was overseen by a "whore's sergeant" (Hurenweibel).

title: Landsknecht


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MacCentral

MacCentral was a web site that provided news and information covering the Apple Macintosh, originally as an independent entity and later as the news service for Mac Publishing Web sites, including Macworld.com and Playlist, before being subsumed by Macworld's own brand.

MacCentral was founded by Canadian businessman Stan Flack and Jim Dalrymple as Associate Editor in 1994. In 1998, MacCentral Online acquired MacGaming. MacCentral Online was purchased by Mac Publishing in 1999. In March 2001, Macworld folded the trade-focused MacWEEK into MacCentral MacCentral was folded into the Macworld brand over a period of several years.

In June 2008 it was announced on the MacMinute news site that MacTech's Community News Scan and Macsimum News will act as caretakers to the archives of MacMinute News and Forums which is where most of Stan's faithful went upon the demise of MacCentral forums. They also announced they would continue to host the MacMinute Forum. Stan's Lounge is crowded with MacCentral and MacMinute faithful in honor of Stan Flack and all that he did for the Macintosh community.

On December 10, 2008 Jim Dalrymple announced that the name MacCentral lives on; with permission from MacWorld, the old MacCentral Forums were opened at www.maccentralforums.com, where eight years of MacCentral forum history could researched. the database of the MacCentral forums has ceased to exist, abbreviated format at archive.gov.

MacCentral chronology

 * September 4, 1995 Stan Flack publishes the first monthly issue of MacCentral using DOCMaker.
 * June 1999 Mac Publishing, LLC, the publisher of Macworld magazine and Macworld Online, purchases MacCentral Online.
 * February 2001 In a move to assert the dominance of the Macworld brand among its brands including MacCentral.com and MacWEEK.com, Mac Publishing redirects Maccentral.com traffic to a subdomain of Macworld.com.
 * May 9, 2001 Stan Flack leaves MacCentral to publish MacMinute News on a new web site.
 * April 14, 2008, Stan Flack, MacCentral founder, passes away at his home on Prince Edward Island.

MacCentral Forum
Despite the rebranding of MacCentral, a cadre of loyal readers continued to maintain a presence in the MacCentral Forum, a community that remained in operation without being prominently linked to from anywhere on Macworld's primary site. Those forums were shut down in 2008, with many of the forum members relocating to the MacMinute Café forum. And then, with the shutting down of the MacMinute forums in May 2008 the majority of forum members moved to MacCentral Cafe or other places on the internet.

MacCentral Forum chronology

 * November 9, 1996 Maccentral in the past
 * January 31, 1998 MacCentral Reader Forum opened.
 * March 26, 2002 Beginning of what becomes the Forum 2002 Mosaic Project. This community project culminates with posters and signed canvases being sold at Macworld Expo. MacCentral Forum members elect to give the proceeds to United Cerebral Palsy.
 * January 16, 2003 Beginning of the thread to create MacCentral Forum Mosaic 2003.
 * August 8, 2003 Beginning of the thread to create MacCentral Forum 2004 Mosaic.
 * December 14, 2007 Forums integrated into the Macworld website as MacCentral Alumni.
 * January 3, 2008 Forums changed to read only.
 * March 3, 2008 Forum database made inaccessible by Macworld.
 * November, 2008 Stan's Lounge is moved to MacTech servers and quickly becomes a haven for lost MacCentral and MacMinute Forum members.
 * December 10, 2008 James Dalrymple announces that the old MacCentral Forums are now in read/write format at www.maccenralforums.com
 * April 14, 2009 The anniversary of Stan Flack's death finds the MacCentral/MacMinute forum operating within the MacTech website. Stan's Lounge is still averaging over 300 posts per day.
 * October 28, 2010 Polymerase is banned.

title: MacCentral


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Outhwaite Homes

Outhwaite Homes is a public development under jurisdiction of the Cuyahoga Metropolitan Housing Authority in Cleveland, Ohio. Built in 1935 by architects Edward J. Maier, Travis G. Walsh, and Leo J. Barrett and possibly named after Joseph H. Outhwaite, it was the first federally funded public housing in the Cleveland area and one of the first in the U.S. At the time of its opening, rent was listed at $4.78. The 100-plus-unit complex at East 55th Street and Woodland Avenue is, in autumn of 2011, in the final stages of redevelopment. The Outhwaite Homes, like other housing developments in the CMHA, provides residential housing for low-income families in the eastern section of downtown Cleveland.

History
Two famous Cleveland brothers, Louis Stokes (US Congressman for over 28 years) and Carl Stokes (first black mayor of a major US city 1967) were among the first residents of Outhwaite.

Louis Stokes Museum On September 13, 2007, CMHA opened the Louis Stokes Museum in honor of Cleveland-native Louis Stokes, a former congressman and civil rights attorney. The Louis Stokes Museum, located at CMHA's Outhwaite Homes, displays Stokes memorabilia, video interviews and footage, awards, and a written history about Congressman Louis Stokes and his rise to prominence. Louis and his brother Carl, Cleveland's first black mayor, grew up in the estates. The museum is located at 2453 East 43rd Street, Cleveland, Ohio 44104.

Judge Sara J. Harper Children's Library Judge Sara J. Harper founded the Sara J. Harper Children's Library in 1992 at CMHA's Outhwaite Homes on East 43rd Street. Judge Harper grew up in the estates along with Carl and Louis Stokes. She is the first black woman graduate of the Case Western Reserve University Law School; the first woman to serve on the judiciary of the U.S. Marine Corps Reserve; one of the first two women to win a seat on the Ohio Court of Appeals; and the first black woman to sit by assignment on the Ohio Supreme Court. The mission of the library is to provide a safe environment that encourages and promotes reading, learning, and positive avenues for self-realization. It is located at 2453 East 43rd Street, Cleveland, Ohio 44104.

Construction Details (1935 dollars):

Total Cost: $3,211,727

Land: $742,492

Construction: $2,420,335

Landscaping: $48,900

Construction cost per room (incl. landscaping): $1,139,95

title: Outhwaite Homes


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Quirinal Palace

The Quirinal Palace (Palazzo del Quirinale ) is a historic building in Rome, Italy, one of the three current official residences of the President of the Italian Republic, together with Villa Rosebery in Naples and the Tenuta di Castelporziano, an estate on the outskirts of Rome, some 25 km from the centre of the city. It is located on the Quirinal Hill, the highest of the seven hills of Rome in an area colloquially called Monte Cavallo. It has served as the residence for thirty popes, four kings of Italy and twelve presidents of the Italian Republic.

The Quirinal Palace was selected by Napoleon to be his residence par excellence as emperor. However, he never stayed there because of the French defeat in 1814 and the subsequent European Restoration.

The palace extends for an area of 110,500 square meters and is the eleventh-largest palace in the world.

Origins
The current site of the palace has been in use since ancient Roman times, as excavations in the gardens testify. On this hill, the Romans built temples for several deities, from Flora to Quirinus, after whom the hill was named. During the reign of Constantine the Great, the last complex of Roman baths was built here, as the statues of the twins Castor and Pollux taming the horses decorating the fountain in the square testify. The Quirinal, being the highest hill in Rome, was much sought after and became a popular location for the Roman patricians, who built luxurious villas there. An example is the remains of a villa in the Quirinal gardens, where a mosaic, part of the old floor has been found.

Foundation of the current palace

The palace, located on the Via del Quirinale and facing onto the Piazza del Quirinale, was built in 1583 by Pope Gregory XIII as a papal summer residence. The Pope, who wanted to find a location which was far away from the humidity and stench coming from the River Tiber and likewise the unhealthy conditions of the Lateran Palace, chose the Quirinal hill as it was one of the most suitable places in Rome. On the site, there was already a small villa owned by the Carafa family and rented to Luigi d'Este. The Pope commissioned the architect Ottaviano Mascherino to build a palace with porticoed parallel wings and an internal courtyard by incorporating the Carafa villa, the original nucleus of the palace, later known as the Gregorian building. That project was not fully completed due to the Pope's death in 1585. However, it is still recognisable in the north part of the courtyard, especially in the double loggia facade, topped by the panoramic Torre dei Venti (tower of the winds) or Torrino. To the latter, a bell tower was added according to a project by Carlo Maderno and Francesco Borromini.

From the 17th century
Pope Paul V (r. 1605–1621) commissioned the completion of the work on the main building of the palace.

The palace was also used as the location for papal conclaves in 1823, 1829, 1831, and 1846. It served as a papal residence and housed the central offices responsible for the civil government of the Papal States until 1870. In September 1870, what was left of the Papal States was occupied militarily and annexed to the Kingdom of Italy. Some five months later, in 1871, Rome became the capital of the new Italian state. The palace became the official royal residence of the Kings of Italy, though some of these, notably King Victor Emmanuel III (reigned 1900–1946) actually lived in a private residence elsewhere (Villa Savoia), leaving the Quirinal to be used simply as a suite of offices and for state functions. The monarchy was abolished in 1946 and the palace became the official residence and workplace for the presidents of the Italian Republic. Still, some have declined the Colle residence and kept their usual Roman residence: for example, Sandro Pertini preferred his old flat near the Trevi Fountain.

The palace's façade was designed by Domenico Fontana. Its Great Chapel was designed by Carlo Maderno. It contains frescos by Guido Reni, but the most famous fresco is the Blessing Christ by Melozzo da Forlì, placed over the stairs. The palace grounds include a famous set of gardens laid out in the 17th century.

Palace
The palace is composed of the main building, which is built around the majestic courtyard, with the most beautiful halls and rooms of the complex environments that serve as representative of the Presidency of the Republic, while the offices and apartments of the head of state are housed in the Fuga building at the end of the Manica lunga, the long building on the side of Quirinal street (via del Quirinale in Italian). On the piano nobile of the Manica lunga lie the opulent imperial apartments, which were specially arranged, decorated and furnished for two visits of Kaiser Wilhelm II (in 1888 and 1893) and which now houses the monarchs or foreign heads of state visiting the president of the republic. The palace, in its totality, has 1,200 rooms.

The rooms of the palace housed in the main building are: The shape of the staircase was very useful during the papal period since the double-crossed ramp allowed to reach the two main rooms of the papal palace directly: the Throne room, today the Great hall of cuirassiers, and the Consistory room, today the Great hall of banquets, at the time used as papal private apartments. This was the throne room of the papal palace, where ambassadors and dignitaries were received and public audiences were held. The royal guards stood here during the Savoy period. Today, the room serves for public audiences, receptions, and solemn ceremonies held by the Presidency of the Republic. It is the largest chapel in the building, built with the same size and shape as the Sistine Chapel so that the same ceremonial could be repeated both in the Vatican and in the Quirinal. Four popes were elected here. Today the chapel hosts concerts and religious ceremonies. It is one among the rooms formerly part of the papal private apartments, today hosting informal meetings of the president of the republic on occasion. The Yellow Room was once part of a seventy-meter long gallery built by Pope Alexander VII, later ordered split by Napoleon to serve as Empress's private residence. It features magnificent yellow fabrics lined to the walls, hence the name of the room. In modern times, under the republic, the Napoleonic decorations were mostly removed, revealing the original ornaments. This room hosted the throne during the Savoy reign. This room was used to receive dignitaries before the ceremonies, a purpose it still fulfills. This room is one of the latest Savoy's interventions opened in the 1940s by dismantling rooms of the private papal apartments. The name derives from the tapestries on the walls representing the twelve labors of Hercules. This room was also opened by dismantling rooms of the papal private apartment. It is a passage room; the name derives from the precious cabinets displayed here. This extraordinary masterpiece of the architect Ottaviano Mascarino is the original staircase of the Gregorian building. The ramp winds up to aspirate to culminate in a skylight. In the Savoy era, we risked losing this masterpiece as well as all the other rooms of the Gregorian building: some princes wanted it to be destroyed to make room for a large ballroom; the project was eventually halted due to excessive expenses. This room was used as a dining room by the Savoy family. The enfilade of the tapestries room, of the mirrors room and of the great hall of banquets was conceived in the Savoy era for the court galas which were held once a month, on the third Thursday of the month. Arriving from the staircase of honour, you first came across the great Hall of banquets, followed by the mirrors room and by the tapestries room. The tapestries room, in particular, was used as a conversation room. It is the smaller chapel of the palace. In the Savoy era, it was deconsecrated and used by servants to wash dishes since it was close to the zodiac room. This room was used by the Savoy as a ballroom. Here today are held audiences of the president of the republic with few participants and the oath of the Judges of the Constitutional Court. In the papal era, this room was used as the consistory room where the Cardinal's College met. From the Savoy period onwards, banquets and state dinners have been held here. Today, the new government is also sworn in here. Here the president of the republic meets the entourage of visiting foreign dignitaries. The name of the room derives from the tapestries on display, made on Agnolo Bronzino's own design.
 * The Staircase of Honour
 * The Great Hall of the Cuirassiers
 * The Pauline Chapel
 * The First State Room
 * The Room of the Virtues
 * The Room of the Flood
 * The Room of the Loggias
 * The Doorkeepers Room
 * The Balcony Room
 * The St. John Parlour
 * The Yellow Room
 * The Augustus Room
 * The Ambassadors Room
 * The Hercules Room
 * The Cabinets Room
 * The Mascarino Staircase
 * The Loggia of Honour
 * The Bees Room
 * The Zodiac Room
 * The Room of Paul V factories
 * The Tapestries Room
 * The Chapel of the Annunciation
 * The Mirrors Room
 * The Great Hall of Banquets
 * The Bronzino Room
 * The Druso Room
 * The president's former audience room
 * The Lilla Tapestries Toom
 * The Napoleonic Parlour
 * The Piffetti Library
 * The Music Room
 * The War Room or Victory Room
 * The Peace Room
 * The Ladies Room

Gardens
The Quirinal Gardens, famous for the privileged position that makes them almost an "island" elevated above Rome, were, over the centuries, changed depending on the tastes and needs of the papal court.

The current arrangement complements the garden "formal" seventeenth century facing the original core of the building with the garden "romantic" in the second half of the eighteenth century, preserving at that time the elegant Coffee House built by Ferdinando Fuga as reception room of Benedict XIV Lambertini, decorated by paintings of Pompeo Batoni and Giovanni Paolo Pannini.

Within the Quirinal gardens lies the famous water organ built between 1997 and 1999 by Barthélemy Formentelli based on the characteristics of the previous nineteenth-century organ. The organ is fed by a waterfall with a jump of 18 meters and has a single keyboard of 41 notes with a first short octave, without pedalboard.

Overall, the Quirinal gardens extend over 4 hectares (10 acres).

By means of a trap door located in the gardens, entry can be gained to the archaeological excavations that have unearthed the remains of the original temple to the god Quirinus and some insulae of the imperial age.

title: Quirinal Palace


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Gentoo penguin

The gentoo penguin (Pygoscelis papua) is a penguin species (or possibly a species complex) in the genus Pygoscelis, most closely related to the Adélie penguin (P. adeliae) and the chinstrap penguin (P. antarcticus). The earliest scientific description was made in 1781 by Johann Reinhold Forster with a type locality in the Falkland Islands. The species calls in a variety of ways, but the most frequently heard is a loud trumpeting, which the bird emits with its head thrown back.

Names
The application of "gentoo" to the penguin is unclear. Gentoo was an Anglo-Indian term to distinguish Hindus from Muslims. The English term may have originated from the Portuguese gentio ("pagan, gentile"). Some speculate that the white patch on the bird's head was thought to resemble a turban.

It may also be a variation of another name for this bird, "Johnny penguin", with Johnny being the Spanish counterpart of Juanito and sounding vaguely like gentoo. The Johnny rook, a predator, is likely named after the Johnny penguin.

The specific name papua is a misnomer; in the original description, Johann Reinhold Forster, a naturalist who had circumnavigated the world with Captain James Cook, mistakenly assumed that the species occurred in Papua (New Guinea), the closest gentoos being over 6000 km to the south (on Macquarie Island). No penguins are found in New Guinea. Others trace the error to a "possibly fraudulent claim" in 1776 by French naturalist Pierre Sonnerat, who also alleged a Papuan location for the king penguin despite never having been to the island himself.

Taxonomy
The gentoo penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago (Mya), about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adélie penguins split off from the other members of the genus around 19 Mya and the chinstrap and gentoo finally diverged around 14 Mya.

There are 4 subspecies recognized by the International Ornithological Congress:

Although the population on the Kerguelen Islands is tentatively included in taeniata, it may also be a distinct subspecies.

Before 2021, only two subspecies of the gentoo penguin have been recognised: P. p. papua (subantarctic gentoo) and the smaller P. p. ellsworthi (Antarctic gentoo). However, a 2020 study suggested that the gentoo penguin be split into a species complex of four morphologically similar but separate species: the northern gentoo penguin (P. papua sensu stricto), the southern gentoo penguin (P. ellsworthi), the eastern gentoo penguin (P. taeniata) and the newly described South Georgia gentoo penguin (P. poncetii). The International Ornithological Congress incorporated the results of this study in 2021, but relegated the newly recognized or newly described species to being subspecies of P. papua.

Description

The gentoo penguin is easily recognised by the wide, white stripe extending like a bonnet across the top of its head and its bright orange-red bill. It has pale whitish-pink, webbed feet and a fairly long tail – the most prominent tail of all penguin species. Chicks have grey backs with white fronts. As the gentoo penguin waddles along on land, its tail sticks out behind, sweeping from side to side, hence the scientific name Pygoscelis, which means "rump-tailed".

Gentoo penguins can reach a length of 70 to 90 cm, making them the third-largest species of penguin after the emperor penguin and the king penguin. Males have a maximum weight around 8.5 kg just before moulting and a minimum weight of about 4.9 kg just before mating. For females, the maximum weight is 8.2 kg just before moulting, but their weight drops to as little as 4.5 kg when guarding the chicks in the nest. Birds from the north are on average 700 g heavier and 10 cm longer than the southern birds. Southern gentoo penguins reach 75 – in length. They are the fastest underwater swimmers of all penguins, reaching speeds up to 36 km/h. Gentoos are well adapted to extremely cold and harsh climates.

Breeding

The breeding colonies of gentoo penguins are located on ice-free surfaces. Settlements can be located directly on the shoreline or considerably inland. They prefer shallow coastal areas and often nest between tufts of grass. In South Georgia, for example, breeding colonies are 2 km inland. In colonies farther inland, where the penguins nest in grassy areas, they shift location slightly yearly because the grass becomes trampled over time.

Gentoos breed on many subantarctic islands. The main colonies are on the Falkland Islands, South Georgia and the South Sandwich Islands and Kerguelen Islands; smaller colonies are found on: Macquarie Island, Heard Islands, Crozet Islands, South Shetland Islands and the Antarctic Peninsula. The total breeding population is estimated to be over 600,000 birds. Gentoos breed monogamously and infidelity is typically punished with banishment from the colony. Nests are usually made from a roughly circular pile of stones and can be quite large, 20 cm high and 25 cm in diameter. The stones are jealously guarded, and their ownership can be the subject of noisy disputes and physical attacks between individuals. They are also prized by the females, even to the point that a male penguin can obtain the favours of a female by offering her a choice stone.

Two eggs are laid, both weighing around 130 g. The parents share incubation, changing duty daily. The eggs hatch after 34 to 36 days. The chicks remain in the nests for around 30 days before joining other chicks in the colony and forming crèches. The chicks moult into subadult plumage and go out to sea at around 80 to 100 days.

Diet
Gentoos mainly live on fish, crustaceans such as krill and shrimp, and cephalopods. In February and March, crustaceans make up about 10% of the diet, but from March to June, it is about 75%. From June to October, grey rockcod (Lepidonotothen squamifrons) make up 90% of their diet. Cephalopods make up only 10% of the diet throughout the year.

Gentoos are opportunistic feeders, and around the Falklands are known to take roughly equal proportions of fish (Patagonotothen sp., Thysanopsetta naresi, Micromesistius australis), squat lobsters (Munida gregaria) and squid (Loligo gahi, Gonatus antarcticus, Moroteuthis ingens). Other prey include Channichthys rhinoceratus and octopuses.

Physiology
The gentoos' diet is high in salt, as they eat organisms with relatively the same salinity as seawater, which can lead to complications associated with high sodium concentrations in the body, especially for gentoo chicks. To counteract this, gentoos, as well as many other marine bird species, have a highly developed salt gland located above their eyes that takes the high concentration of sodium within the body and produces a highly saline-concentrated solution that drips out of the body from the tip of the beak.

Gentoo penguins do not store as much fat as Adélie penguins, their closest relative; gentoos require less energy investment when hunting because the net gain of energy after hunting is greater in gentoos than Adélies. As embryos, gentoos require a lot of energy to develop. Oxygen consumption is high for a developing gentoo embryo. As the embryo grows and requires more oxygen, consumption increases exponentially until the gentoo chick hatches. By then, the chick is consuming around 1800 ml O2 per day.

Predators

In the sea, leopard seals, sea lions and killer whales are all predators of the gentoo. On land, no predators of full-grown, healthy gentoo penguins exist. Skuas and giant petrels regularly kill many chicks and steal eggs; petrels kill injured and sick adult gentoos. Various other seabirds, such as the kelp gull and snowy sheathbill, also snatch chicks and eggs. Skuas on King George Island have been observed attacking and injuring adult gentoo penguins in apparent territorial disputes.

Conservation status
The population of Pygoscelis papua in the maritime Antarctic is rapidly increasing. Due to regional climate changes, they colonise previously inaccessible territories southwards., the IUCN Red List lists the gentoo as least concerned with a stable population trend, although rapid declines in some key areas are believed to be driving a moderate overall decline in the species population. Examples include Bird Island, South Georgia, where the population has fallen by two-thirds over 25 years. Many threats to this species, including pollution, hunting, fishing and human recreational activities continue to affect them.

In popular culture
The Linux distribution Gentoo Linux is named after the gentoo penguin. This is a nod to the fact that the penguin is the fastest swimming penguin, as Gentoo Linux aims to be a high-performance operating system. The mascot for Linux in general is a penguin.

title: Gentoo penguin