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Donald A. Wollheim

Donald Allen Wollheim (October 1, 1914 – November 2, 1990) was an American science fiction editor, publisher, writer, and fan. As an author, he published under his own name as well as under pseudonyms, including David Grinnell, Martin Pearson, and Darrell G. Raynor. A founding member of the Futurians, he was a leading influence on science fiction development and fandom in the 20th-century United States. Ursula K. Le Guin called Wollheim "the tough, reliable editor of Ace Books, in the Late Pulpalignean Era, 1966 and '67", which is when he published her first two novels in Ace Double editions.

Involvement in science fiction fandom
The 1979 first edition of The Encyclopedia of Science Fiction calls Wollheim "one of the first and most vociferous SF fans." He published numerous fanzines and co-edited the early Fanciful Tales of Time and Space. His importance to early fandom is chronicled in the 1974 book The Immortal Storm by Sam Moskowitz and in the 1977 book The Futurians by Damon Knight.

Wollheim organized an event later considered the first American science fiction convention, when a group from New York met with a group from Philadelphia on October 22, 1936, in Philadelphia. The modern Philcon convention claims descent from this event. Out of this meeting, plans were formed for regional and national meetings, including the first-ever Worldcon.

Wollheim was a member of the New York Science Fiction League, one of the clubs established by Hugo Gernsback to promote science fiction. When payment was not forthcoming for the first story he sold to Gernsback, Wollheim formed a group with several other authors, and successfully sued for payment. He was expelled from the Science Fiction League as "a disruptive influence" but was later reinstated. From the September 1935 issue of Gernsback's Wonder Stories: "THREE MEMBERS EXPELLED

It grieves us to announce that we have found the first disloyalty in our organization... These members we expelled on June 12th. Their names are Donald A. Wollheim, John B. Michel, and William S. Sykora—three active fans who just got themselves onto the wrong road."

In 1937 Wollheim founded the Fantasy Amateur Press Association, whose first mailing (July 1937) included this statement from him: "There are many fans desiring to put out a voice who dare not, for fear of being obliged to keep it up, and for the worry and time taken by subscriptions and advertising. It is for them and for the fan who admits it is his hobby and not his business that we formed the FAPA." In 1938, with several friends, he formed the Futurians—arguably the best-known of the science fiction clubs. At one time or another, the membership included Isaac Asimov, Frederik Pohl, Cyril Kornbluth, James Blish, John Michel, Judith Merril, Robert A. W. Lowndes, Richard Wilson, Damon Knight, Virginia Kidd, and Larry T. Shaw. In 1943 Wollheim married fellow Futurian Elsie Balter (1910–1996). It proved to be a lasting marriage and publishing partnership.

The Futurians became less fan-oriented and more professional after 1940. Its conferences and workshops focused on writing, editing, and publishing, with many of its members interested in all three.

Work as author
Wollheim's first story, "The Man from Ariel", was published in the January 1934 issue of Wonder Stories when he was nineteen. He was not paid for the story, and when he learned that other authors had not been paid either, he said so in the Bulletin of the Terrestrial Fantascience Guild. Publisher Hugo Gernsback eventually settled with Wollheim and the other authors out of court for $75. However, when Wollheim submitted another story ("The Space Lens") under the pseudonym Millard Verne Gordon, he was once again cheated by Gernsback who published it in the September 1935 issue. His third known story was published in Fanciful Tales of Time and Space, Fall 1936, a fanzine that he edited himself. That year he also published and edited another short-lived fanzine, Phantagraph.

Wollheim's stories were published regularly from 1940; at the same time he was becoming an important editor. In the 1950s and 60s he wrote chiefly novels. He usually used pseudonyms for works aimed at grownups, and wrote children's novels under his own name. Notable and popular were the eight "Mike Mars" books for children, which explored different facets of the NASA space program. Also well-received were the "Secret" books for young readers: The Secret of Saturn's Rings (1954), Secret of the Martian Moons (1955), and The Secret of the Ninth Planet (1959). As Martin Pearson he published the "Ajax Calkins" series, which became the basis for his novel Destiny's Orbit (1962). A sequel, Destination: Saturn was published in 1967 in collaboration with Lin Carter. The Universe Makers (1971) is a discussion of themes and philosophy in science fiction.

One of Wollheim's short stories, "Mimic", was made into the film of the same name by director and co-writer Guillermo del Toro, released in 1997.

His daughter Betsy declared: "In true editorial fashion, he was honest about the quality of his own writing. He felt it was fair to middling at best. He always knew that his great talent was as an editor."

Career as editor and publisher
Robert Silverberg said that Wollheim was "one of the most significant figures in 20th century American science fiction publishing," adding, "A plausible case could be made that he was the most significant figure—responsible in large measure for the development of the science fiction paperback, the science fiction anthology, and the whole post-Tolkien boom in fantasy fiction."

In late 1940, Wollheim noticed a new magazine titled Stirring Detective and Western Stories on the newsstands. He wrote to the publishers, Albing Publications, to see if they were interested in adding a science fiction title to their list, and he was invited to meet them. They did not have capital, however, and only guaranteed him a salary if the magazines were successful. He approached some of his fellow Futurians for free stories (some published under pseudonyms to protect their reputations with paying editors). It resulted in Wollheim's editing two of the earliest periodicals devoted to science fiction, the Cosmic Stories and Stirring Science Stories magazines starting in February 1941. After the magazines were cancelled later in 1941, Wollheim was able to find another publisher, Manhattan Fiction Publications, and a fourth issue of Stirring appeared, dated March 1942. Wartime constraints prevented ongoing publication, and there were no more issues of either title.

Wollheim edited the first science fiction anthology to be mass-marketed, The Pocket Book of Science Fiction (1943). It was also the first book containing the words "science fiction" in the title. It included works by Robert A. Heinlein, Theodore Sturgeon, T. S. Stribling, Stephen Vincent Benét, Ambrose Bierce, and H. G. Wells. In 1945 Wollheim edited the first hardcover anthology from a major publisher and the first omnibus, The Viking Portable Novels of Science. He also edited the first anthology of original science fiction, The Girl With the Hungry Eyes (1947), although there is evidence that this last was originally intended to be the first issue of a new magazine.

Between 1947 and 1951 he was editor at the pioneering paperback publisher Avon Books, where he made available highly affordable editions of the works of A. Merritt, H. P. Lovecraft, and C. S. Lewis' Silent Planet space trilogy, bringing these previously little known authors a wide readership. During this period he also edited eighteen issues of the influential Avon Fantasy Reader as well as three of the Avon Science Fiction Reader. These periodicals contained mostly reprints and a few original stories.

In 1952 Wollheim left Avon to work for A. A. Wyn at the Ace Magazine Company and spearheaded a new paperback book list, Ace Books. In 1953 he introduced science fiction to the Ace lineup, and for 20 years as editor-in-chief was responsible for their multi-genre list and, most important to him, their renowned sf list. Wollheim invented the Ace Doubles series which consisted of pairs of books, usually by different authors, bound back-to-back with two "front" covers. Because these paired books had to fit a fixed total page length, one or both were usually abridged to fit, and Wollheim often made other editorial alterations—as witness the differences between Poul Anderson's Ace novel War of the Wing-Men and its definitive revised edition, The Man Who Counts. Among the authors who made their paperback debuts in Ace Doubles were Philip K. Dick, Samuel R. Delany, Leigh Brackett, Ursula K. Le Guin, and John Brunner. William S. Burroughs' first book, Junkie, was published as an Ace Double. Wollheim also helped develop Marion Zimmer Bradley, Robert Silverberg, Avram Davidson, Fritz Leiber, Andre Norton, Thomas Burnett Swann, Jack Vance, and Roger Zelazny, among others. While at Ace, he and co-editor Terry Carr began an annual anthology series, The World's Best Science Fiction, the first collection of what they considered the best of the prior year's short stories, from magazines, hardcovers, paperback collections and other anthologies.

In the early 1960s Ace reintroduced Edgar Rice Burroughs' work, which had long been out of print, and in 1965, Ace bought the paperback rights to Dune (Herbert's title worried Wollheim, who feared it would be mistaken for a western). Eventually, Ace introduced single paperback books and became one of the preeminent genre publishers. Ace and Ballantine dominated sf in the 1960s and built the genre by publishing original material as well as reprints.

Tolkien controversy
Prior to the 1960s, no large American paperback publisher would publish fantasy. It was believed that there was no public demand for it and that it would not sell. Wollheim published an unauthorized paperback edition of J. R. R. Tolkien's The Lord of the Rings in three volumes. It was the first mass-market paperback edition of Tolkien's epic. Wollheim did not consider himself a fantasy fan. In a 2006 interview his daughter, Betsy Wollheim, said:

"When he called up Professor Tolkien in 1964 and asked if he could publish Lord of the Rings as Ace paperbacks, Tolkien said he would never allow his great works to appear in so 'degenerate a form' as the paperback book. Don was one of the fathers of the entire paperback industry, since before he spearheaded the Ace line he was the originating editor-in-chief of the Avon paperback list in 1945, so he took this personally. He was very offended. He did a little research and discovered a loophole in the copyright. Houghton Mifflin, Tolkien's American hardcover publisher, had neglected to protect the work in the United States. So, incensed by Tolkien's response, he realized that he could legally publish them and did.

This brash action (which ultimately benefited his primary competitors) was really the Big Bang that founded the modern fantasy field, and only someone like my father could have done that. He did pay Tolkien, and he was responsible for making not only Tolkien but Ballantine Books extremely wealthy. He was bitter about that, and frankly that's probably why he never got the Hugo he wanted. But if he hadn't done it, who knows when — or if — those books would have been published in paperback?"

This account was disputed by Tolkien, who claimed that he never received any communication from Ace prior to publication of their version. In any case, Tolkien had previously authorized paperback editions of The Hobbit and Tree and Leaf. The authorized Ballantine paperback edition of The Lord of the Rings was then published in November, 1965. Ace subsequently agreed to cease publishing the unauthorized edition and to pay Tolkien for their sales following a grassroots campaign by Tolkien's U.S. fans. A 1993 court determined that the copyright loophole suggested by Ace Books was invalid and its paperback edition was found to have been a violation of copyright under U.S. law (at this time, the U.S. had yet to join the International Copyright Convention, and most laws on the books existed to protect domestic creations from foreign infringement. Houghton Mifflin was technically in violation of the law when they exceeded their import limits and failed to renew their interim copyright). In the Locus obituary for Donald Wollheim, however, more details emerge:

"Houghton-Mifflin had imported sheets instead of printing their own edition, but they didn't want to sell paperback rights. Ace printed the first paperback edition and caused such a furor that Tolkien rewrote the books enough to get a new copyright, then sold them to Ballantine. The rest is history. Although Ace and Wollheim have become the villains in the Tolkien publishing gospel, it's probable that the whole Tolkien boom would not have happened if Ace hadn't published them."

Foundation of DAW Books
Wollheim left Ace in 1971. Frederik Pohl describes the circumstances: "Unfortunately, when Wyn died [in 1968] the company was sold to a consortium headed by a bank. ... Few of them had any publishing experience before they found themselves running Ace. It showed. Before long, bills weren't being paid, authors' advances and royalties were delayed, budgets were cut back, and most of Donald's time was spent trying to soothe authors and agents who were indignant, and had every right to be, at the way they were treated." Upon leaving Ace, he and his wife, Elsie Balter Wollheim, founded DAW Books, which he named for his initials. DAW can claim to be the first mass market specialist science fiction and fantasy fiction publishing house. DAW issued its first four titles in April 1972. Most of the writers whom he had developed at Ace went with him to DAW: Marion Zimmer Bradley, Andre Norton, Philip K. Dick, John Brunner, A. Bertram Chandler, Kenneth Bulmer, Gordon R. Dickson, A. E. van Vogt, and Jack Vance. In later years, when his distributor, New American Library, threatened to withhold Thomas Burnett Swann's Biblical historical fantasy How Are the Mighty Fallen (1974), owing to its homosexual content, Wollheim fought vigorously against their decision, and they relented.

His later author discoveries included Tanith Lee, Jennifer Roberson, Michael Shea, Tad Williams, Celia S. Friedman, and C. J. Cherryh, whose Downbelow Station (1982) was the first DAW book to win the Hugo Award for best novel. He was also able to give a number of British writers, including E. C. Tubb, Brian Stableford, Barrington Bayley, and Michael Coney, a new American audience. He published translations of international sf as well as anthologies of translated stories, Best From the Rest of the World. With the help of Arthur W. Saha, Wollheim also edited and published the popular "Annual World's Best Science Fiction" anthology from 1971 until his death.

Recognition
Algis Budrys in 1966 gave Wollheim a Galaxy Bookshelf award "for doing his job". Upon Wollheim's death in 1990, the prolific editor Robert Silverberg argued (above) that he may have been "the most significant figure" in American SF publishing.

Robert Jordan credited Wollheim for helping to launch Jordan's career. Wollheim made an offer for Jordan's first novel, Warriors of the Ataii, though he withdrew the offer when Jordan requested some minor changes to the contract. Jordan claimed that Wollheim's first, 'laudatory' letter convinced him that he could write, and so he chose to remember the first letter and forget about the second. The novel was never published, but Jordan went on to write the immensely successful The Wheel of Time series for a different publisher.

Marion Zimmer Bradley referred to him as "a second father", Frederick Pohl called him "a founder", and Robert Silverberg says he was "seriously underrated" and "one of the great shapers of science-fiction publishing in the United States". In 1977 scholar Robert Scholes named Wollheim "one of the most important editors and publishers of science fiction."

From 1975 on, Wollheim received several special awards for his contributions to science fiction and to fantasy, including one at the 1975 World SF Convention and runner-up to Ian & Betty Ballantine at the 1975 World Fantasy Convention.

The Science Fiction and Fantasy Hall of Fame inducted him in 2002, its seventh class of two deceased and two living persons. He is the third person inducted primarily for his work as editor or publisher, after the inaugural 1996 pair Hugo Gernsback and John W. Campbell.

World's Best Science Fiction (with Terry Carr)

 * World's Best Science Fiction: 1965 (also known as World's Best Science Fiction: First Series)
 * World's Best Science Fiction: 1966 (also known as World's Best Science Fiction: Second Series)
 * World's Best Science Fiction: 1967 (also known as World's Best Science Fiction: Third Series)
 * World's Best Science Fiction: 1968 (also known as World's Best Science Fiction: Fourth Series)
 * World's Best Science Fiction: 1969
 * World's Best Science Fiction: 1970
 * World's Best Science Fiction: 1971

The Annual World's Best SF (with Arthur W. Saha)

 * The 1972 Annual World's Best SF (also known as Wollheim's World's Best SF: Series One)
 * The 1973 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Two)
 * The 1974 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Three)
 * The 1975 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Four)
 * The 1976 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Five)
 * The 1977 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Six)
 * The 1978 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Seven)
 * The 1979 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Eight)
 * The 1980 Annual World's Best SF (also known as Wollheim's World's Best SF: Series Nine)
 * The 1981 Annual World's Best SF
 * The 1982 Annual World's Best SF
 * The 1983 Annual World's Best SF
 * The 1984 Annual World's Best SF
 * The 1985 Annual World's Best SF
 * The 1986 Annual World's Best SF
 * The 1987 Annual World's Best SF
 * The 1988 Annual World's Best SF
 * The 1989 Annual World's Best SF
 * The 1990 Annual World's Best SF

Novels

 * Across Time (as David Grinnell)
 * Destination: Saturn (as David Grinnell, with Lin Carter)
 * Destiny's Orbit (as David Grinnell; published as an Ace Double with John Brunner's Times Without Number)
 * The Edge of Time (as David Grinnell)
 * The Martian Missile (as David Grinnell)
 * One Against the Moon (1956, The World Publishing Company, Library of Congress Catalog Card Number: 56-9261)
 * The Secret of the Martian Moons (1955, Winston Science Fiction series)
 * The Secret of the Ninth Planet (1959, Winston Science Fiction series)
 * The Secret of Saturn's Rings (1954, Winston Science Fiction series)
 * To Venus! To Venus! (as David Grinnell)

Mike Mars series
Source:

 * Mike Mars, Astronaut (1961)
 * Mike Mars Flies the X-15 (1961)
 * Mike Mars at Cape Canaveral (renamed Mike Mars at Cape Kennedy when published in paperback in 1966) (1961)
 * Mike Mars in Orbit (1961)
 * Mike Mars Flies the Dyna-Soar (1962)
 * Mike Mars, South Pole Spaceman (1962)
 * Mike Mars and the Mystery Satellite (1963)
 * Mike Mars Around the Moon (1964)

Nonfiction

 * A Year Among the Girls (as Darrell G. Raynor) (1966) (concerning his crossdressing experiences and Casa Susanna)
 * The Universe Makers: Science Fiction Today (1971): a "survey and behind-the-scenes look" at science fiction from the Golden Age onward) )

Personal life
Wollheim also actively practiced cross-dressing as a woman throughout his life, and he regularly attended events at Casa Susanna in the Catskills of upstate New York.

title: Donald A. Wollheim


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Digital cinema

Digital cinema refers to the adoption of digital technology within the film industry to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the Internet or dedicated satellite links, or by sending hard drives or optical discs such as Blu-ray discs.

Digital movies are projected using a digital video projector instead of a film projector, are shot using digital movie cameras and are edited using a non-linear editing system (NLE). The NLE is often a video editing application installed in one or more computers that may be networked to access the original footage from a remote server, share or gain access to computing resources for rendering the final video, and allow several editors to work on the same timeline or project.

Alternatively a digital movie could be a film reel that has been digitized using a motion picture film scanner and then restored, or, a digital movie could be recorded using a film recorder onto film stock for projection using a traditional film projector.

Digital cinema is distinct from high-definition television and does not necessarily use traditional television or other traditional high-definition video standards, aspect ratios, or frame rates. In digital cinema, resolutions are represented by the horizontal pixel count, usually 2K (2048×1080 or 2.2 megapixels) or 4K (4096×2160 or 8.8 megapixels). The 2K and 4K resolutions used in digital cinema projection are often referred to as DCI 2K and DCI 4K. DCI stands for Digital Cinema Initiatives.

As digital cinema technology improved in the early 2010s, most theaters across the world converted to digital video projection. Digital cinema technology has continued to develop over the years with 3D, RPX, 4DX and ScreenX, allowing moviegoers with more immersive experiences.

History
The transition from film to digital video was preceded by cinema's transition from analog to digital audio, with the release of the Dolby Digital (AC-3) audio coding standard in 1991. Its main basis is the modified discrete cosine transform (MDCT), a lossy audio compression algorithm. It is a modification of the discrete cosine transform (DCT) algorithm, which was first proposed by Nasir Ahmed in 1972 and was originally intended for image compression. The DCT was adapted into the MDCT by J.P. Princen, A.W. Johnson and Alan B. Bradley at the University of Surrey in 1987, and then Dolby Laboratories adapted the MDCT algorithm along with perceptual coding principles to develop the AC-3 audio format for cinema needs. Cinema in the 1990s typically combined analog photochemical images with digital audio.

Digital media playback of high-resolution 2K files has at least a 20-year history. Early video data storage units (RAIDs) fed custom frame buffer systems with large memories. In early digital video units, the content was usually restricted to several minutes of material. Transfer of content between remote locations was slow and had limited capacity. It was not until the late 1990s that feature-length films could be sent over the "wire" (Internet or dedicated fiber links). On October 23, 1998, Digital Light Processing (DLP) projector technology was publicly demonstrated with the release of The Last Broadcast, the first feature-length movie, shot, edited and distributed digitally. In conjunction with Texas Instruments, the movie was publicly demonstrated in five theaters across the United States (Philadelphia, Portland (Oregon), Minneapolis, Providence, and Orlando).

Foundations
In the United States, on June 18, 1999, Texas Instruments' DLP Cinema projector technology was publicly demonstrated on two screens in Los Angeles and New York for the release of Lucasfilm's Star Wars Episode I: The Phantom Menace. In Europe, on February 2, 2000, Texas Instruments' DLP Cinema projector technology was publicly demonstrated, by Philippe Binant, on one screen in Paris for the release of Toy Story 2.

From 1997 to 2000, the JPEG 2000 image compression standard was developed by a Joint Photographic Experts Group (JPEG) committee chaired by Touradj Ebrahimi (later the JPEG president). In contrast to the original 1992 JPEG standard, which is a DCT-based lossy compression format for static digital images, JPEG 2000 is a discrete wavelet transform (DWT) based compression standard that could be adapted for motion imaging video compression with the Motion JPEG 2000 extension. JPEG 2000 technology was later selected as the video coding standard for digital cinema in 2004.

Initiatives
On January 19, 2000, the Society of Motion Picture and Television Engineers, in the United States, initiated the first standards group dedicated towards developing digital cinema. By December 2000, there were 15 digital cinema screens in the United States and Canada, 11 in Western Europe, 4 in Asia, and 1 in South America. Digital Cinema Initiatives (DCI) was formed in March 2002 as a joint project of many motion picture studios (Disney, Fox, MGM, Paramount, Sony Pictures, Universal and Warner Bros.) to develop a system specification for digital cinema. The same month it was reported that the number of cinemas equipped with digital projectors had increased to about 50 in the US and 30 more in the rest of the world.

In April 2004, in cooperation with the American Society of Cinematographers, DCI created standard evaluation material (the ASC/DCI StEM material) for testing of 2K and 4K playback and compression technologies. DCI selected JPEG 2000 as the basis for the compression in the system the same year. Initial tests with JPEG 2000 produced bit rates of around 75–125 Mbit/s for 2K resolution and 100–200 Mbit/s for 4K resolution.

Worldwide deployment
In China, in June 2005, an e-cinema system called "dMs" was established and was used in over 15,000 screens spread across China's 30 provinces. dMs estimated that the system would expand to 40,000 screens in 2009. In 2005 the UK Film Council Digital Screen Network launched in the UK by Arts Alliance Media creating a chain of 250 2K digital cinema systems. The roll-out was completed in 2006. This was the first mass roll-out in Europe. AccessIT/Christie Digital also started a roll-out in the United States and Canada. By mid 2006, about 400 theaters were equipped with 2K digital projectors with the number increasing every month. In August 2006, the Malayalam digital movie Moonnamathoral, produced by Benzy Martin, was distributed via satellite to cinemas, thus becoming the first Indian digital cinema. This was done by Emil and Eric Digital Films, a company based at Thrissur using the end-to-end digital cinema system developed by Singapore-based DG2L Technologies.

In January 2007, Guru became the first Indian film mastered in the DCI-compliant JPEG 2000 Interop format and also the first Indian film to be previewed digitally, internationally, at the Elgin Winter Garden in Toronto. This film was digitally mastered at Real Image Media Technologies in India. In 2007, the UK became home to Europe's first DCI-compliant fully digital multiplex cinemas; Odeon Hatfield and Odeon Surrey Quays (in London), with a total of 18 digital screens, were launched on 9 February 2007. By March 2007, with the release of Disney's Meet the Robinsons, about 600 screens had been equipped with digital projectors. In June 2007, Arts Alliance Media announced the first European commercial digital cinema Virtual Print Fee (VPF) agreements (with 20th Century Fox and Universal Pictures). In March 2009 AMC Theatres announced that it closed a $315 million deal with Sony to replace all of its movie projectors with 4K digital projectors starting in the second quarter of 2009; it was anticipated that this replacement would be finished by 2012.

In January 2011, the total number of digital screens worldwide was 36,242, up from 16,339 at end 2009 or a growth rate of 121.8 percent during the year. There were 10,083 d-screens in Europe as a whole (28.2 percent of global figure), 16,522 in the United States and Canada (46.2 percent of global figure) and 7,703 in Asia (21.6 percent of global figure). Worldwide progress was slower as in some territories, particularly Latin America and Africa. As of 31 March 2015, 38,719 screens (out of a total of 39,789 screens) in the United States have been converted to digital, 3,007 screens in Canada have been converted, and 93,147 screens internationally have been converted. At the end of 2017, virtually all of the world's cinema screens were digital (98%).

Despite the fact that today, virtually all global movie theaters have converted their screens to digital cinemas, some major motion pictures even as of 2019 are shot on film. For example, Quentin Tarantino released his latest film Once Upon a Time in Hollywood in 70 mm and 35 mm in selected theaters across the United States and Canada.

Elements
In addition to the equipment already found in a film-based movie theatre (e.g., a sound reinforcement system, screen, etc.), a DCI-compliant digital cinema requires a DCI-compliant digital projector and a powerful computer known as a server. Movies are supplied to the theatre as a digital file called a Digital Cinema Package (DCP). For a typical feature film, this file will be anywhere between 90 GB and 300 GB of data (roughly two to six times the information of a Blu-ray disc) and may arrive as a physical delivery on a conventional computer hard drive or via satellite or fibre-optic broadband Internet. As of 2013, physical deliveries of hard drives were most common in the industry. Promotional trailers arrive on a separate hard drive and range between 200 GB and 400 GB in size. The contents of the hard drive(s) may be encrypted.

Regardless of how the DCP arrives, it first needs to be copied onto the internal hard drives of the server, either via a USB port, or through a faster eSATA connection, or via a closed network, a process known as "ingesting." (USB is used mostly for single trailers.) DCPs can be, and in the case of feature films almost always are, encrypted, to prevent illegal copying and piracy. The necessary decryption keys are supplied separately, usually as email attachments or via download, and then "ingested" via USB. Keys are time-limited and will expire after the end of the period for which the title has been booked. They are also locked to the hardware (server and projector) that is to screen the film, so if the theatre wishes to move the title to another screen or extend the run, a new key must be obtained from the distributor. Several versions of the same feature can be sent together. The original version (OV) is used as the basis of all the other playback options. Version files (VF) may have a different sound format (e.g. 7.1 as opposed to 5.1 surround sound) or subtitles. 2D and 3D versions are often distributed on the same hard drive.

The playback of the content is controlled by the server using a "playlist". As the name implies, this is a list of all the content that is to be played as part of the performance. The playlist will be created by a member of the theatre's staff using proprietary software that runs on the server. In addition to listing the content to be played the playlist also includes automation cues that allow the playlist to control the projector, the sound system, auditorium lighting, tab curtains and screen masking (if present), etc. The playlist can be started manually, by clicking the "play" button on the server's monitor screen, or automatically at pre-set times.

Digital Cinema Initiatives
Digital Cinema Initiatives (DCI), a joint venture of the six major studios, published the first version (V1.0) of a system specification for digital cinema in July 2005. The main declared objectives of the specification were to define a digital cinema system that would "present a theatrical experience that is better than what one could achieve now with a traditional 35mm Answer Print", to provide global standards for interoperability such that any DCI-compliant content could play on any DCI-compliant hardware anywhere in the world and to provide robust protection for the intellectual property of the content providers.

The DCI specification calls for picture encoding using the ISO/IEC 15444-1 "JPEG2000" (.j2c) standard and use of the CIE XYZ color space at 12 bits per component encoded with a 2.6 gamma applied at projection. Two levels of resolution for both content and projectors are supported: 2K (2048×1080) or 2.2 MP at 24 or 48 frames per second, and 4K (4096×2160) or 8.85 MP at 24 frames per second. The specification ensures that 2K content can play on 4K projectors and vice versa. Smaller resolutions in one direction are also supported (the image gets automatically centered). Later versions of the standard added additional playback rates (like 25 fps in SMPTE mode). For the sound component of the content the specification provides for up to 16 channels of uncompressed audio using the "Broadcast Wave" (.wav) format at 24 bits and 48 kHz or 96 kHz sampling.

Playback is controlled by an XML-format Composition Playlist, into an MXF-compliant file at a maximum data rate of 250 Mbit/s. Details about encryption, key management, and logging are all discussed in the specification as are the minimum specifications for the projectors employed including the color gamut, the contrast ratio and the brightness of the image. While much of the specification codifies work that had already been ongoing in the Society of Motion Picture and Television Engineers (SMPTE), the specification is important in establishing a content owner framework for the distribution and security of first-release motion-picture content.

National Association of Theatre Owners
In addition to DCI's work, the National Association of Theatre Owners (NATO) released its Digital Cinema System Requirements. The document addresses the requirements of digital cinema systems from the operational needs of the exhibitor, focusing on areas not addressed by DCI, including access for the visually impaired and hearing impaired, workflow inside the cinema, and equipment interoperability. In particular, NATO's document details requirements for the Theatre Management System (TMS), the governing software for digital cinema systems within a theatre complex, and provides direction for the development of security key management systems. As with DCI's document, NATO's document is also important to the SMPTE standards effort.

E-Cinema
The Society of Motion Picture and Television Engineers (SMPTE) began work on standards for digital cinema in 2000. It was clear by that point in time that HDTV did not provide a sufficient technological basis for the foundation of digital cinema playback. In Europe, India and Japan however, there is still a significant presence of HDTV for theatrical presentations. Agreements within the ISO standards body have led to these non-compliant systems being referred to as Electronic Cinema Systems (E-Cinema).

Projectors for digital cinema
Only three manufacturers make DCI-approved digital cinema projectors; these are Barco, Christie and Sharp/NEC. Except for Sony, who used to use their own SXRD technology, all use the Digital Light Processing (DLP) technology developed by Texas Instruments (TI). D-Cinema projectors are similar in principle to digital projectors used in industry, education, and domestic home cinemas, but differ in two important respects. First, projectors must conform to the strict performance requirements of the DCI specification. Second, projectors must incorporate anti-piracy devices intended to enforce copyright compliance such as licensing limits. For these reasons all projectors intended to be sold to theaters for screening current release movies must be approved by the DCI before being put on sale. They now pass through a process called CTP (compliance test plan). Because feature films in digital form are encrypted and the decryption keys (KDMs) are locked to the serial number of the server used (linking to both the projector serial number and server is planned in the future), a system will allow playback of a protected feature only with the required KDM.

DLP Cinema
Three manufacturers have licensed the DLP Cinema technology developed by Texas Instruments (TI): Christie Digital Systems, Barco, and NEC. While NEC is a relative newcomer to Digital Cinema, Christie is the main player in the U.S. and Barco takes the lead in Europe and Asia. Initially DCI-compliant DLP projectors were available in 2K only, but from early 2012, when TI's 4K DLP chip went into full production, DLP projectors have been available in both 2K and 4K versions. Manufacturers of DLP-based cinema projectors can now also offer 4K upgrades to some of the more recent 2K models. Early DLP Cinema projectors, which were deployed primarily in the United States, used limited 1280×1024 resolution or the equivalent of 1.3 MP (megapixels). Digital Projection Incorporated (DPI) designed and sold a few DLP Cinema units (is8-2K) when TI's 2K technology debuted but then abandoned the D-Cinema market while continuing to offer DLP-based projectors for non-cinema purposes. Although based on the same 2K TI "light engine" as those of the major players they are so rare as to be virtually unknown in the industry. They are still widely used for pre-show advertising but not usually for feature presentations.

TI's technology is based on the use of digital micromirror devices (DMDs). These are MEMS devices that are manufactured from silicon using similar technology to that of computer chips. The surface of these devices is covered by a very large number of microscopic mirrors, one for each pixel, so a 2K device has about 2.2 million mirrors and a 4K device about 8.8 million. Each mirror vibrates several thousand times a second between two positions: In one, light from the projector's lamp is reflected towards the screen, in the other away from it. The proportion of the time the mirror is in each position varies according to the required brightness of each pixel. Three DMD devices are used, one for each of the primary colors. Light from the lamp, usually a Xenon arc lamp similar to those used in film projectors with a power between 1 kW and 7 kW, is split by colored filters into red, green and blue beams which are directed at the appropriate DMD. The 'forward' reflected beam from the three DMDs is then re-combined and focused by the lens onto the cinema screen. Later projectors may use lasers instead of xenon lamps.

Sony SXRD
Alone amongst the manufacturers of DCI-compliant cinema projectors Sony decided to develop its own technology rather than use TI's DLP technology. SXRD (Silicon X-tal (Crystal) Reflective Display) projectors have only ever been manufactured in 4K form and, until the launch of the 4K DLP chip by TI, Sony SXRD projectors were the only 4K DCI-compatible projectors on the market. Unlike DLP projectors, however, SXRD projectors do not present the left and right eye images of stereoscopic movies sequentially, instead they use half the available area on the SXRD chip for each eye image. Thus during stereoscopic presentations the SXRD projector functions as a sub 2K projector, the same for HFR 3D Content.

However, Sony decided in late April, 2020 that they would no longer manufacture digital cinema projectors.

Stereo 3D images
In late 2005, interest in digital 3-D stereoscopic projection led to a new willingness on the part of theaters to co-operate in installing 2K stereo installations to show Disney's Chicken Little in 3-D film. Six more digital 3-D movies were released in 2006 and 2007 (including Beowulf, Monster House and Meet the Robinsons). The technology combines a single digital projector fitted with either a polarizing filter (for use with polarized glasses and silver screens), a filter wheel or an emitter for LCD glasses. RealD uses a "ZScreen" for polarisation and MasterImage uses a filter wheel that changes the polarity of projector's light output several times per second to alternate quickly the left-and-right-eye views. Another system that uses a filter wheel is Dolby 3D. The wheel changes the wavelengths of the colours being displayed, and tinted glasses filter these changes so the incorrect wavelength cannot enter the wrong eye. XpanD makes use of an external emitter that sends a signal to the 3D glasses to block out the wrong image from the wrong eye.

Laser
RGB laser projection produces the purest BT.2020 colors and the brightest images.

LED screen for digital cinema
In Asia, on July 13, 2017, an LED screen for digital cinema developed by Samsung Electronics was publicly demonstrated on one screen at Lotte Cinema World Tower in Seoul. The first installation in Europe is in Arena Sihlcity Cinema in Zürich. These displays do not use a projector; instead they use a LED video wall, and can offer higher contrast ratios, higher resolutions, and overall improvements in image quality. Sony already sells MicroLED displays as a replacement for conventional cinema screens.

Effect on distribution
Digital distribution of movies has the potential to save money for film distributors. To print an 80-minute feature film can cost US$1,500 to $2,500, so making thousands of prints for a wide-release movie can cost millions of dollars. In contrast, at the maximum 250 megabit-per-second data rate (as defined by DCI for digital cinema), a feature-length movie can be stored on an off-the-shelf 300 GB hard drive for $50 and a broad release of 4000 'digital prints' might cost $200,000. In addition hard drives can be returned to distributors for reuse. With several hundred movies distributed every year, the industry saves billions of dollars. The digital-cinema roll-out was stalled by the slow pace at which exhibitors acquired digital projectors, since the savings would be seen not by themselves but by distribution companies. The Virtual Print Fee model was created to address this by passing some of the saving on to the cinemas. As a consequence of the rapid conversion to digital projection, the number of theatrical releases exhibited on film is dwindling. As of 4 May 2014, 37,711 screens (out of a total of 40,048 screens) in the United States have been converted to digital, 3,013 screens in Canada have been converted, and 79,043 screens internationally have been converted.

Telecommunication
Realization and demonstration, on October 29, 2001, of the first digital cinema transmission by satellite in Europe  of a feature film by Bernard Pauchon, Alain Lorentz, Raymond Melwig and Philippe Binant.

Live broadcasting to cinemas or event cinema
Digital cinemas can deliver live broadcasts from performances or events. This began initially with live broadcasts from the New York Metropolitan Opera delivering regular live broadcasts into cinemas and has been widely imitated ever since. Leading territories providing the content are the UK, the US, France and Germany. The Royal Opera House, Sydney Opera House, English National Opera and others have found new and returning audiences captivated by the detail offered by a live digital broadcast featuring handheld and cameras on cranes positioned throughout the venue to capture the emotion that might be missed in a live venue situation. In addition these providers all offer additional value during the intervals e.g. interviews with choreographers, cast members, a backstage tour which would not be on offer at the live event itself. Other live events in this field include live theatre from NT Live, Branagh Live, Royal Shakespeare Company, Shakespeare's Globe, the Royal Ballet, Mariinsky Ballet, the Bolshoi Ballet and the Berlin Philharmoniker.

In the last ten years this initial offering of the arts has also expanded to include live and recorded music events such as Take That Live, One Direction Live, Andre Rieu, live musicals such as the recent Miss Saigon and a record-breaking Billy Elliot Live In Cinemas. Live sport, documentary with a live question and answer element such as the recent Oasis documentary, lectures, faith broadcasts, stand-up comedy, museum and gallery exhibitions, TV specials such as the record-breaking Doctor Who fiftieth anniversary special The Day Of The Doctor, have all contributed to creating a valuable revenue stream for cinemas large and small all over the world. Subsequently, live broadcasting, formerly known as Alternative Content, has become known as Event Cinema and a trade association now exists to that end. Ten years on the sector has become a sizeable revenue stream in its own right, earning a loyal following amongst fans of the arts, and the content limited only by the imagination of the producers it would seem. Theatre, ballet, sport, exhibitions, TV specials and documentaries are now established forms of Event Cinema. Worldwide estimations put the likely value of the Event Cinema industry at $1bn by 2019.

Event Cinema currently accounts for on average between 1-3% of overall box office for cinemas worldwide but anecdotally it's been reported that some cinemas attribute as much as 25%, 48% and even 51% (the Rio Bio cinema in Stockholm) of their overall box office. It is envisaged ultimately that Event Cinema will account for around 5% of the overall box office globally. Event Cinema saw six worldwide records set and broken over from 2013 to 2015 with notable successes Dr Who ($10.2m in three days at the box office - event was also broadcast on terrestrial TV simultaneously), Pompeii Live by the British Museum, Billy Elliot, Andre Rieu, One Direction, Richard III by the Royal Shakespeare Company.

Event Cinema is defined more by the frequency of events rather than by the content itself. Event Cinema events typically appear in cinemas during traditionally quieter times in the cinema week such as the Monday-Thursday daytime/evening slot and are characterised by the One Night Only release, followed by one or possibly more 'Encore' releases a few days or weeks later if the event is successful and sold out. On occasion more successful events have returned to cinemas some months or even years later in the case of NT Live where the audience loyalty and company branding is so strong the content owner can be assured of a good showing at the box office.

Pros
The digital formation of sets and locations, especially in the time of growing film series and sequels, is that virtual sets, once computer generated and stored, can be easily revived for future films. Considering digital film images are documented as data files on hard disk or flash memory, varying systems of edits can be executed with the alteration of a few settings on the editing console with the structure being composed virtually in the computer's memory. A broad choice of effects can be sampled simply and rapidly, without the physical constraints posed by traditional cut-and-stick editing. Digital cinema allows national cinemas to construct films specific to their cultures in ways that the more constricting configurations and economics of customary film-making prevented. Low-cost cameras and computer-based editing software have gradually enabled films to be produced for minimal cost. The ability of digital cameras to allow film-makers to shoot limitless footage without wasting costly film has transformed film production in some Third World countries. From consumers' perspective digital prints do not deteriorate with the number of showings. Unlike film, there is no projection mechanism or manual handling to add scratches or other physically generated artefacts. Provincial cinemas that would have received old prints can give consumers the same cinematographic experience (all other things being equal) as those attending the premiere.

The use of NLEs in movies allows for edits and cuts to be made non-destructively, without actually discarding any footage.

Cons
A number of high-profile film directors, including Christopher Nolan, Paul Thomas Anderson, David O. Russell and Quentin Tarantino have publicly criticized digital cinema and advocated the use of film and film prints. Most famously, Tarantino has suggested he may retire because, though he can still shoot on film, because of the rapid conversion to digital, he cannot project from 35 mm prints in the majority of American cinemas. Steven Spielberg has stated that though digital projection produces a much better image than film if originally shot in digital, it is "inferior" when it has been converted to digital. He attempted at one stage to release Indiana Jones and the Kingdom of the Crystal Skull solely on film. Paul Thomas Anderson recently was able to create 70-mm film prints for his film The Master.

Film critic Roger Ebert criticized the use of DCPs after a cancelled film festival screening of Brian DePalma's film Passion at New York Film Festival as a result of a lockup due to the coding system.

The theoretical resolution of 35 mm film is greater than that of 2K digital cinema. 2K resolution (2048×1080) is also only slightly greater than that of consumer based 1080p HD (1920x1080). However, since digital post-production techniques became the standard in the early 2000s, the majority of movies, whether photographed digitally or on 35 mm film, have been mastered and edited at the 2K resolution. Moreover, 4K post production was becoming more common as of 2013. As projectors are replaced with 4K models the difference in resolution between digital and 35 mm film is somewhat reduced. Digital cinema servers utilize far greater bandwidth over domestic "HD", allowing for a difference in quality (e.g., Blu-ray colour encoding 4:2:0 48 Mbit/s MAX datarate, DCI D-Cinema 4:4:4 250 Mbit/s 2D/3D, 500 Mbit/s HFR3D). Each frame has greater detail.

Owing to the smaller dynamic range of digital cameras, correcting poor digital exposures is more difficult than correcting poor film exposures during post-production. A partial solution to this problem is to add complex video-assist technology during the shooting process. However, such technologies are typically available only to high-budget production companies. Digital cinemas' efficiency of storing images has a downside. The speed and ease of modern digital editing processes threatens to give editors and their directors, if not an embarrassment of choice then at least a confusion of options, potentially making the editing process, with this 'try it and see' philosophy, lengthier rather than shorter. Because the equipment needed to produce digital feature films can be obtained more easily than film projectors, producers could inundate the market with cheap productions and potentially dominate the efforts of serious directors. Because of the quick speed in which they are filmed, these stories sometimes lack essential narrative structure.

Pros
The electronic transferring of digital film, from central servers to servers in cinema projection booths, is an inexpensive process of supplying copies of newest releases to the vast number of cinema screens demanded by prevailing saturation-release strategies. There is a significant saving on print expenses in such cases: at a minimum cost per print of $1200–2000, the cost of film print production is between $5–8 million per movie. With several thousand releases a year, the probable savings offered by digital distribution and projection are over $1 billion. The cost savings and ease, together with the ability to store film rather than having to send a print on to the next cinema, allows a larger scope of films to be screened and watched by the public; minority and small-budget films that would not otherwise get such a chance.

Cons
The initial costs for converting theaters to digital are high: $100,000 per screen, on average. Theaters have been reluctant to switch without a cost-sharing arrangement with film distributors. A solution is a temporary Virtual Print Fee system, where the distributor (who saves the money of producing and transporting a film print) pays a fee per copy to help finance the digital systems of the theaters. A theater can purchase a film projector for as little as $10,000 (though projectors intended for commercial cinemas cost two to three times that; to which must be added the cost of a long-play system, which also costs around $10,000, making a total of around $30,000–$40,000) from which they could expect an average life of 30–40 years. By contrast, a digital cinema playback system—including server, media block, and projector—can cost two to three times as much, and would have a greater risk of component failure and obsolescence. (In Britain the cost of an entry-level projector including server, installation, etc., would be £31,000 [$50,000].)

Archiving digital masters has also turned out to be both tricky and costly. In a 2007 study, the Academy of Motion Picture Arts and Sciences found the cost of long-term storage of 4K digital masters to be "enormously higher—up to 11 times that of the cost of storing film masters." This is because of the limited or uncertain lifespan of digital storage: No current digital medium—be it optical disc, magnetic hard drive or digital tape—can reliably store a motion picture for as long as a hundred years or more (a timeframe for film properly stored). The short history of digital storage media has been one of innovation and, therefore, of obsolescence. Archived digital content must be periodically removed from obsolete physical media to up-to-date media. The expense of digital image capture is not necessarily less than the capture of images onto film; indeed, it is sometimes greater.

Filmography

 * Christopher Kenneally, Side by Side, 2012. IMDb

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

title: Digital cinema


text:
Democratic Progressive Party

The Democratic Progressive Party (DPP) is a centre to centre-left Taiwanese nationalist  political party in Taiwan. It is currently the major ruling party in Taiwan, controlling both the presidency and the central government, also the dominant party in the Pan-Green Coalition.

Founded in 1986 by Hsu Hsin-liang, Hsieh Tsung-min and Lin Shui-chuan, a year prior to the end of martial law, the DPP is one of two major parties in Taiwan, the other being the historically dominant Kuomintang (KMT), which previously ruled the country as a one-party state. It has traditionally been associated with a strong advocacy of human rights, emerging against the authoritarian White Terror that was initiated by the KMT, as well as the promotion of Taiwanese nationalism and identity. Lai Ching-te is the current chairperson of the DPP from 2023, who also serves as the incumbent President and is the third member of the DPP to hold the presidency; he succeeded fellow DPP member Tsai Ing-wen.

The DPP is a longtime member of Liberal International and a founding member of the Council of Asian Liberals and Democrats. It represented Taiwan in the Unrepresented Nations and Peoples Organization (UNPO). The DPP is widely classified as socially liberal having been founded as a party for human rights, including factions within the party supporting same-sex marriage and other LGBT rights. On foreign policy, the DPP is more willing to increase military expenditures to prevent military intimidation from the People's Republic of China (PRC) owing to the ambiguous political status of Taiwan. It favors closer ties with democratic nations such as Japan and the United States, as well as the nations of ASEAN as part of its New Southbound Policy. The party is frequently accused by the PRC government of being a primary force in Taiwan to "prevent the Chinese nation from achieving complete reunification" and "halt the process of national rejuvenation" due to the party's outspoken advocacy of the Taiwanese nationalism, its supportive attitude to Taiwanese enjoying the right to decide their own future, and its firm opposition to the notion of "One China", including the alleged "1992 Consensus" narratives by both the Chinese Communist Party (CCP) and KMT.

History
The DPP's roots were in the Tangwai movement, which formed in opposition to the Kuomintang's one-party authoritarian rule under the "party-state" system during martial law. This movement culminated in the formation of the DPP as an alternative, but still illegal, party on 28 September 1986 by eighteen organizing members at Grand Hotel Taipei, with a total of 132 people joining the party in attendance. The new party members contested the 1986 election as "nonpartisan" candidates since competing parties would remain illegal until the following year. These early members of the party, like the tangwai, drew heavily from the ranks of family members and defense lawyers of political prisoners, as well as intellectuals and artists who had spent time abroad. These individuals were strongly committed to political change toward democracy and freedom of speech, press, assembly, and association.

The tangwai were not a unified political unit and consisted of factions which carried over into the early DPP. At its founding the DPP consisted of three factions: the Kang group ,a moderate faction led by Kang Ning-hsiang, New Tide faction, consisting of intellectuals and social activists led by Wu Nai-ren and Chiou I-jen, and the Progress Faction led by Lin Cheng-chieh, a waishengren opposed to independence. Moderates would later coalesce around the Formosa faction, founded by those arrested during the Formosa Incident after their release from prison. In the early days of the party, the Formosa faction focused on winning elections by wielding the star power of its leaders, while New Tide would focus on ideological mobilization and developing grassroots support for social movements. As a result, the Formosa faction would become more moderate, often bending to public opinion, while New Tide would become more ideologically cohesive. By 1988 the Formosa Faction would dominate high-level positions within the party.

The party did not at the outset give explicit support to an independent Taiwanese national identity, partially because moderates such as Hsu Hsin-liang were concerned that such a move that could have invited a violent crackdown by the Kuomintang and alienate voters, but also because some members such as Lin Cheng-chieh supported unification. Partially due to their waning influence within the party and partially due to their ideological commitment, between 1988 and 1991 the New Tide Faction would push the independence issue, bolstered by the return of pro-independence activists from overseas who were previously barred from Taiwan. In 1991, in order to head off the New Tide, party chairman Hsu Hsin-liang of the moderate Formosa faction agreed to include language in the party charter which advocated for the drafting of a new constitution as well as declaration of a new Republic of Taiwan via referendum (which resulted in many pro-unification members leaving the party). However, the party would quickly begin to walk back on this language, and eventually in 1999 the party congress passed a resolution that Taiwan was already an independent country, under the official name "Republic of China", and that any constitutional changes should be approved by the people via referendum, while emphasizing the use of the name "Taiwan" in international settings.

Despite its lack of electoral success, the pressure that the DPP created on the ruling KMT via its demands are widely credited in the political reforms of the 1990s, most notably the direct popular election of Republic of China's president and all representatives in the National Assembly and Legislative Yuan, as well the ability to open discuss events from the past such as the February 28 Incident and its long aftermath of martial law, and space for a greater variety of political views and advocacy. Once the DPP had representation in the Legislative Yuan, the party used the legislature as a forum to challenge the ruling KMT.

In 1996, DPP Chairman Shih Ming-teh united with the New Party to run for the President of the Legislative Yuan, but lost by one vote. The vote that was missing was legislator Chang Chin-cheng's failure to vote for Shih. As a result, Chang was expelled from the DPP.

Post-democratization, the DPP shifted their focus to anti-corruption issues, in particular regarding KMT connections to organized crime as well as "party assets" illegally acquired from the government during martial law. Meanwhile, factions continued to form within the DPP as a mechanism for coalition-building within the party; notably, future President Chen Shui-bian would form the Justice Alliance faction.

2000–2008: in minority government

The DPP won the presidency with the election of Chen Shui-bian in March 2000 with a plurality, due to Pan-Blue voters splitting their vote between the Kuomintang and independent candidate James Soong, ending 91 years of KMT rule in the Republic of China. Chen softened the party's stance on independence to appeal to moderate voters, appease the United States, and placate China. He also promised not to change the ROC state symbols or declare formal independence as long as the People's Republic of China did not attack Taiwan. Further, he advocated for economic exchange with China as well as the establishment of transportation links.

In 2002, the DPP became the first party other than the KMT to reach a plurality in the Legislative Yuan following the 2001 legislative election. However, a majority coalition between the KMT, People First Party, and New Party prevented it from taking control of the chamber. This coalition was at odds with the presidency from the beginning, and led to President Chen's abandonment of the centrist positions that he ran his campaign on.

In 2003, Chen announced a campaign to draft a referendum law as well as a new constitution, a move which appealed to the fundamentalist wing of the DPP. By now, the New Tide faction had begun to favor pragmatic approaches to their pro-independence goals and dominated decision-making positions within the party. By contrast, grassroots support was divided largely between moderate and fundamentalist wings. Though Chen's plans for a referendum on a new constitution were scuttled by the legislature, he did manage to include a largely symbolic referendum on the PRC military threat to coincide with the 2004 presidential election. President Chen Shui-bian would be narrowly re-elected in 2004 after an assassination attempt the day before the election, and in the later legislative election, the pan-blue coalition opposition retained control of the chamber.

President Chen's moves sparked a debate within the party between fundamentalists and moderates who were concerned that voters would abandon their party. The fundamentalists won out, and as a result the DPP would largely follow Chen's lead. The DPP suffered a significant election defeat in nationwide local and county elections in December 2005, while the pan-blue coalition captured 16 of 23 county and city government offices under the leadership of popular Taipei mayor and KMT Party Chairman Ma Ying-jeou. Moderates within the party would blame this loss on the party's fundamentalist turn.

The results led to a shake up of the party leadership. Su Tseng-chang resigned as DPP chairman soon after election results were announced. Su had pledged to step down if the DPP lost either Taipei County or failed to win 10 of the 23 mayor/magistrate positions. Vice President Annette Lu was appointed acting DPP leader. Presidential Office Secretary-General Yu Shyi-kun was elected in a three-way race against legislator Chai Trong-rong and Wong Chin-chu with 54.4% of the vote.

Premier Frank Hsieh, DPP election organizer and former mayor of Kaohsiung twice tendered a verbal resignation immediately following the election, but his resignation was not accepted by President Chen until 17 January 2006 after the DPP chairmanship election had concluded. The former DPP Chairman Su Tseng-chang was appointed to replace Hsieh as premier. Hsieh and his cabinet resigned en masse on 24 January to make way for Su and his new cabinet. President Chen had offered the position of Presidential Office Secretary-General (vacated by Su) to the departing premier, but Hsieh declined and left office criticizing President Chen for his tough line on dealing with China.

In 2005, following the passage of the Anti-Secession Law, the Chen administration issued a statement asserting the position that Taiwan's future should be decided by the people on Taiwan only.

Separate identity from China
On 30 September 2007, the DPP approved a resolution asserting a separate identity from China and called for the enactment of a new constitution for a "normal nation". It struck an accommodating tone by advocating general use of "Taiwan" as the country's name without calling for abandonment of the name Republic of China.

2008–2016: return to opposition
In the national elections held in early months of 2008, the DPP won less than 25% of the seats (38.2% vote share) in the new Legislative Yuan while its presidential candidate, former Kaohsiung mayor Frank Hsieh, lost to KMT candidate Ma Ying-jeou by a wide margin (41.55% vs. 58.45%). In May, the DPP elected moderate Tsai Ing-wen as their new leader over fundamentalist Koo Kwang-ming. Tsai became the first female leader of the DPP and the first female leader to lead a major party in Taiwan.

The first months since backed to the opposition were dominated by press coverage of the travails of Chen Shui-bian and his wife Wu Shu-jen. On 15 August 2008, Chen resigned from the DPP and apologized: "Today I have to say sorry to all of the DPP members and supporters. I let everyone down, caused you humiliation and failed to meet your expectations. My acts have caused irreparable damage to the party. I love the DPP deeply and am proud of being a DPP member. To express my deepest regrets to all DPP members and supporters, I announce my withdrawal from the DPP immediately. My wife Wu Shu-jen is also withdrawing from the party." DPP Chairperson followed with a public statement on behalf of the party: "In regard to Chen and his wife's decision to withdraw from the party and his desire to shoulder responsibility for his actions as well as to undergo an investigation by the party's anti-corruption committee, we respect his decision and accept it."

The DPP vowed to reflect on public misgivings towards the party. Chairperson Tsai insisted on the need for the party to remember its history, defend the Republic of China's sovereignty and national security, and maintain its confidence.

The party re-emerged as a voice in Taiwan's political debate when Ma's administration reached the end of its first year in office. The DPP marked the anniversary with massive rallies in Taipei and Kaohsiung. Tsai's address to the crowd in Taipei on 17 May proclaimed a "citizens' movement to protect Republic of China" seeking to "protect our democracy and protect Republic of China."

2016–2024: in majority government
On 16 January 2016, Taiwan held a general election for its presidency and for the Legislative Yuan. The DPP gained the presidential seat, with the election of Tsai Ing-wen, who received 56.12% of the votes, while her opponent Eric Chu gained 31.2%. In addition, the DPP gained a majority of the Legislative Yuan, winning 68 seats in the 113-seat legislature, up from 40 in 2012 election, thus giving them the majority for the first time in its history.

President Tsai won reelection in the 2020 Taiwanese presidential election on 11 January 2020, and the Democratic Progressive Party retained its legislative majority, winning 61 seats.

2024–present: return to minority government
The 13 January 2024 presidential election and legislative elections led to the election of Lai Ching-te who won with 40.1% of the votes, while his opponents, Hou Yu-ih of the KMT had 33.5% of the votes, and Ko Wen-je of the Taiwan People's Party with 26.5% of the vote. In addition, this election made the DPP the first party to win three consecutive presidential terms since direct elections were introduced in 1996. The DPP was unable to retain its majority in the Legislative Yuan, losing ten seats.

Ideology and policies
The DPP is a centre to centre-left party generally described as progressive. It has also been described as liberal, as well as social democratic. The party takes a Taiwanese nationalist position, advocating for strengthening Taiwanese identity; the party opposes the KMT and mainland China's pan-Chinese nationalism, and criticizes China's claims of sovereignty over Taiwan as 'colonialism' or 'imperialism'. Programs supported by the party include moderate social welfare policies involving the rights of women, senior citizens, children, young people, labor, minorities, indigenous peoples, farmers, and other disadvantaged sectors of the society. Furthermore, its platform includes a legal and political order based on human rights and democracy; balanced economic and financial administration; fair and open social welfare; educational and cultural reform; and, independent defense and peaceful foreign policy with closer ties to United States and Japan. The party is socially liberal and has a progressive stance that includes support for gender equality and same-sex marriage under Tsai's leadership, and also has a conservative base that includes support from the Presbyterian Church in Taiwan.

Stance on Taiwanese independence
The primary political axis in Taiwan involves the issue of Taiwan independence versus Chinese unification. Although the differences tend to be portrayed in polarized terms, both major coalitions have developed modified, nuanced and often complex positions. Though opposed in the philosophical origins, the practical differences between such positions can sometimes be subtle.

The current official position of the party is that Taiwan is an independent and sovereign country whose territory consists of Taiwan and its surrounding smaller islands and whose sovereignty derives only from the ROC citizens living in Taiwan (similar philosophy of self-determination), based on the 1999 "Resolution on Taiwan's Future". It considers Taiwan an independent nation under the name of Republic of China, making a formal declaration of independence unnecessary. Though calls for drafting a new constitution and a declaration of a Republic of Taiwan was written into the party charter in 1991, the 1999 resolution has practically superseded the earlier charter. The DPP rejects the so-called "One China principle" defined in 1992 as the basis for official diplomatic relations with the PRC and advocates a Taiwanese national identity which is separate from mainland China.

By contrast, the KMT or pan-blue coalition agrees that the Republic of China is an independent and sovereign country that is not part of the PRC, but argues that a one China principle (with different definitions across the strait) can be used as the basis for talks with China. The KMT also opposes Taiwan independence and argues that efforts to establish a Taiwanese national identity separated from the Chinese national identity are unnecessary and needlessly provocative. Some KMT conservative officials have called efforts from DPP "anti-China" (opposing migrants from mainland China, who DPP officials did not recognize as Taiwanese, but Chinese). At the other end of the political spectrum, the acceptance by the DPP of the symbols of the Republic of China is opposed by the Taiwan Solidarity Union.

The first years of the DPP as the ruling party drew accusations from the opposition as a self-styled Taiwanese nationalist party, the DPP was itself inadequately sensitive to the ethnographic diversity of Taiwan's population. Where the KMT had been guilty of Chinese chauvinism, the critics charged, the DPP might offer nothing more as a remedy than Hoklo chauvinism. The DPP argues that its efforts to promote a Taiwanese national identity are merely an effort to normalize a Taiwanese identity repressed during years of authoritarian Kuomintang rule.

Support
Since the democratization of Taiwan in the 1990s, the DPP has had its strongest performance in the Hokkien-speaking counties and cities of Taiwan, compared with the predominantly Hakka and Mandarin-speaking counties, that tend to support the Kuomintang.

The deep-rooted hostility between Taiwanese aborigines and (Taiwanese) Hoklo, and the effective KMT networks within aboriginal communities contribute to aboriginal skepticism against the DPP and the aboriginals‘ tendency to vote for the KMT. Aboriginals have criticized politicians for abusing the "indigenization" movement for political gains, such as aboriginal opposition to the DPP's "rectification" by recognizing the Truku for political reasons, where the Atayal and Seediq slammed the Truku for their name rectification. In 2008, the majority of mountain townships voted for Ma Ying-jeou. However, the DPP share of the aboriginal vote has been rising.

Structure
The DPP National Party Congress selects, for two-year terms, the 30 members of the Central Executive Committee and the 11 members of the Central Review Committee. The Central Executive Committee, in turn, chooses the 10 members of the Central Standing Committee. Since 2012, the DPP has had a "China Affairs Committee" to deal with Cross-Strait relations; the name caused some controversy within the party and in the Taiwan media, with critics suggesting that "Mainland Affairs Committee" or "Cross-Strait Affairs Committee" would show less of a hostile "One Country on Each Side" attitude.

Factions
For many years the DPP officially recognized several factions within its membership, such as the New Tide faction, the Formosa faction , the Justice Alliance faction and Welfare State Alliance faction. Different factions endorse slightly different policies and are often generationally identifiable, representing individuals who had entered the party at different times. In 2006, the party ended recognition of factions. The factions have since stated that they will comply with the resolution. However, the factions are still referred to by name in national media.

As of 2022, Taiwan News identified at least 7 factions within the party:

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 * Shih Ming-teh (1 February 1993 – 1 February 2002)
 * Ker Chien-ming (since 1 February 2002)

title: Democratic Progressive Party


text:
Datura

Datura is a genus of nine species of highly poisonous, vespertine-flowering plants belonging to the nightshade family (Solanaceae). They are commonly known as thornapples or jimsonweeds, but are also known as devil's trumpets or mad apple (not to be confused with angel's trumpets, which are placed in the closely related genus Brugmansia). Other English common names include moonflower, devil's weed, and hell's bells. All species of Datura are extremely poisonous and psychoactive, especially their seeds and flowers, which can cause respiratory depression, arrhythmias, fever, delirium, hallucinations, anticholinergic syndrome, psychosis, and death if taken internally.

Due to their effects and symptoms, Datura species have occasionally been used not only as poisons, but also as hallucinogens by various groups throughout history. Traditionally, their psychoactive administration has often been associated with witchcraft and sorcery or similar practices in many cultures, including the Western world. Certain common Datura species have also been used ritualistically as entheogens by some Native American groups.

Non-psychoactive use of plants in the genus is usually done for medicinal purposes, and the alkaloids present in some species have long been considered traditional medicines in both the New and Old Worlds due to the presence of the alkaloids scopolamine and atropine, which are also produced by plants associated with Old World medicine such as Hyoscyamus niger, Atropa belladonna, and Mandragora officinarum.

Etymology
The generic name Datura is taken from Hindi धतूरा ' "thorn-apple", ultimately from Sanskrit धत्तूर ' "white thorn-apple" (referring to Datura metel of Asia). In the Ayurvedic text Sushruta Samhita, different species of Datura are also referred to as ' and '. Dhatura is offered to Shiva in Hinduism. Record of this name in English dates back to 1662. Nathaniel Hawthorne refers to one type in The Scarlet Letter as "apple-Peru". In Mexico, its common name is toloache. The Mexican common name (also spelled tolguacha) derives from the Nahuatl tolohuaxihuitl, meaning "the plant with the nodding head" (in reference to the nodding seed capsules of Datura species belonging to section Dutra of the genus).

Description
Datura species are herbaceous, leafy annuals and short-lived perennials, which can reach up to 2 m in height. The leaves are alternate, 10–20 cm long, and 5–18 cm broad, with a lobed or toothed margin. The flowers are erect or spreading (not pendulous like those of Brugmansia), trumpet-shaped, 5–20 cm long, and 4–12 cm broad at the mouth; colours vary from white to yellow and pale purple. The fruit is a spiny capsule, 4–10 cm long and 2–6 cm broad, splitting open when ripe to release the numerous seeds. The seeds disperse freely over pastures, fields, and even wasteland locations.

Datura belongs to the classic "witches' weeds", along with deadly nightshade, henbane, and mandrake. All parts of the plants are toxic, and the genus has a long history of use for causing delirious states and death. It was well known as an essential ingredient of magical ointments, potions, and witches' brews, most notably Datura stramonium.

In India, D. metel has long been regarded as a poison and aphrodisiac, having been used in Ayurveda as a medicine since ancient times. It features in rituals and prayers to Shiva and also in Ganesh Chaturthi, a festival devoted to the deity Ganesha. The larvae of some Lepidoptera (butterfly and moth) species, including Hypercompe indecisa, eat some Datura species. It has been observed that while insects may prefer to feed on Datura leaves, other animals such as cows will generally avoid consuming them.

Species and cultivars
Classifying Datura as to its species is difficult, and the descriptions of new species often are accepted prematurely. Later, these "new species" are found to be simply varieties that have evolved due to conditions at a specific location. They usually disappear in a few years. Contributing to the confusion is the fact that various species, such as D. wrightii and D. inoxia, are very similar in appearance, and the variation within a species can be extreme. For example, Datura species can change size of plant, leaf, and flowers, all depending on location. The same species, when growing in a half-shady, damp location can develop into a flowering bush half as tall as an adult human of average height, but when growing in a very dry location, will only grow into a thin plant not much more than ankle high, with tiny flowers and a few miniature leaves. Datura species are native to dry, temperate, and subtropical regions. Most species are native to Mexico, which is considered the center of origin of the genus. Several species are considered to have extra-American native ranges: D. ferox (native to China), D. metel (native to India and Southeast Asia), and D. leichardthii (native to Australia), however these may be early introductions from Central America.

A group of South American species formerly placed in the genus Datura are now placed in the distinct genus Brugmansia (Brugmansia differs from Datura in that it is woody (the species being shrubs or small trees) and has indehiscent fruits. The solanaceous tribe Datureae, to which Datura and Brugmansia belong, has recently acquired a new, monotypic genus Trompettia J. Dupin, featuring the species Trompettia cardenasiana, which had hitherto been misclassified as belonging to the genus Iochroma.

Datura specialists, the Preissels, accept only 9 species of Datura, but Kew's Plants of the World Online currently lists the following 14 (out of which the current edition of The Plant List does not list D. arenicola, D. lanosa, and D. pruinosa as accepted spp.):

 * Datura arenicola Gentry ex Bye & Luna
 * Datura ceratocaula Ortega
 * Datura discolor Bernh.
 * Datura ferox L.
 * Datura innoxia Mill.
 * Datura kymatocarpa Barclay
 * Datura lanosa A.S.Barclay ex Bye
 * Datura leichhardtii Benth.
 * Datura metel L.
 * Datura pruinosa Greenm.
 * Datura quercifolia Kunth
 * Datura reburra Barclay
 * Datura stramonium L.
 * Datura wrightii Regel

Of the above, D. leichhardtii is close enough to D. pruinosa to merit demotion to a subspecies and likewise D. ferox and D. quercifolia are close enough in morphology to merit being subsumed in a single species. Furthermore, the Australian provenance of D. leichhardtii, the Chinese provenance of D. ferox, and the Afro-Asiatic provenance of D. metel have been cast into serious doubt, with the three species being almost certainly post-Columbian introductions to the regions to which they were originally thought native.

The case of D. metel is unique in that not only is the plant not a true species at all, but an assemblage of ancient pre-Columbian cultivars created from D. innoxia in the Greater Antilles, but evidence is mounting that it was introduced to the Indian subcontinent no later than the second century CE – whether by natural or human agency is, as yet, unknown – making it one of the most ancient plant introductions (if not the most ancient) from the New World to the Old World (see Columbian Exchange).

D. arenicola is a remarkable new species, described only in 2013, of very restricted range, and so distinctive as to have merited the creation for it of the new section Discola [not to be confused with the species name D. discolor] within the genus. The specific name arenicola means "loving (i.e. "thriving in") sand".

American Brugmansia and Datura Society, Inc. (ABADS) is designated in the 2004 edition of the International Code of Nomenclature for Cultivated Plants as the official International Cultivar Registration Authority for Datura. This role was delegated to ABADS by the International Society for Horticultural Science in 2002.

Past classified species

 * D. lanosa
 * D. suaveolens

Cultivation
Datura species are usually sown annually from the seed produced in the spiny capsules, but, with care, the tuberous-rooted perennial species may be overwintered. Most species are suited to being planted outside or in containers. As a rule, they need warm, sunny places and soil that will keep their roots dry. When grown outdoors in good locations, the plants tend to reseed themselves and may become invasive. In containers, they should have porous, aerated potting soil with adequate drainage. The plants are susceptible to fungi in the root area, so anaerobic organic enrichment such as anaerobically composted organic matter or manure, should be avoided.

Toxicity
All Datura plants contain tropane alkaloids such as scopolamine and atropine, primarily in their seeds and flowers, as well as the roots of certain species such as D. wrightii. Because of the presence of these substances, Datura has been used for centuries in some cultures as a poison. A given plant's toxicity depends on its age, where it is growing, and the local weather conditions. These variations make Datura exceptionally hazardous as a drug. Since datura directly causes the effects of anticholinergic syndrome, the symptoms of its toxicity are often cited by the traditional mnemonic: "Blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone". Datura, as well as long-term psychoactive/toxic usage of other anticholinergic drugs, also appear to significantly increase the risk of developing dementia.

In traditional cultures, a great deal of experience with and detailed knowledge of Datura was critical to minimize harm. Many tragic incidents result from modern users ingesting or smoking Datura. For example, in the 1990s and 2000s, the United States media reported stories of adolescents and young adults dying or becoming seriously ill from intentionally ingesting Datura. Deliberate or inadvertent poisoning resulting from smoking jimsonweed and other related species has been reported as well. Although most poisonings occur with more common species of Datura such as D. stramonium, several reports in the medical literature indicate deaths from D. ferox intoxication. Children are especially vulnerable to atropine poisoning. In some parts of Europe and India, Datura has been a popular poison for suicide and murder. From 1950 to 1965, the State Chemical Laboratories in Agra, India, investigated 2,778 deaths caused by ingesting Datura. A group called Thugs (practicers of thuggee) were reportedly devotees of an Indian religious cult made up of robbers and assassins who strangled or poisoned their victims in rituals devoted to the Hindu goddess Kali. They were alleged to employ Datura in many such poisonings, using it also to induce drowsiness or stupefaction, making strangulation easier.

Datura toxins may be ingested accidentally by consumption of honey produced by several wasp species, including Brachygastra lecheguana, during the Datura blooming season. These semi-domesticated honey wasps apparently collect Datura nectar for honey production, which can lead to poisoning.

The U.S. Centers for Disease Control and Prevention reported accidental poisoning resulting in hospitalization for a family of six who inadvertently ingested Datura used as an ingredient in stew.

In some places around the world, such as India due to the Drug & Cosmetic Act 1940 & Rule 1995, buying, selling, or cultivating Datura plants is prohibited. Solanaceous tribes with a similar chemistry (i.e. a similar tropane alkaloid content), include the Hyoscyameae, containing such well-known toxic species as Hyoscyamus niger and Atropa belladonna, the Solandreae containing the genus Solandra ("chalice vines") and the Mandragoreae, named for the famous Mandragora officinarum, most of which are considered traditional witches' herbs and poisons.

Effects of ingestion
Datura is considered a deliriant. Due to the potent combination of anticholinergic substances it contains, Datura intoxication typically produces the effects of anticholinergic delirium (usually involving a complete or relative inability to differentiate reality from fantasy); bizarre thoughts, hyperthermia; tachycardia; bizarre, and possibly violent behavior; dry skin; dry mouth; illusions; and severe mydriasis (dilated pupils) with resultant painful photophobia that can last several days. Muscle stiffness, urinary retention, temporary paralysis, disrobing, emotional bluntness, dysphoria, and confusion are often reported, and pronounced amnesia is another commonly reported effect. The psychoactive alkaloids scopolamine and atropine are also both known for their characteristic hyperactive effects and ability to cause stark and dream-like hallucinations. The onset of symptoms generally occurs around 30 to 60 minutes after ingesting the herb. These symptoms generally last from 24 to 48 hours, but have been reported in some cases to last two weeks or longer.

Treatment
Due to their agitated behavior and confused mental state, people with acute Datura poisoning or intoxication are typically hospitalized. Gastric lavage and the administration of activated charcoal can be used to reduce the stomach's absorption of the ingested material, and the drug physostigmine is used to reverse the effect of the poisons. Benzodiazepines can be given to calm the patient's agitation, and supportive care with oxygen, hydration, and symptomatic treatment is often provided. Observation of the patient is indicated until the symptoms resolve, usually from 24 to 36 hours after ingestion of the Datura.

Psychoactive use
In Pharmacology and Abuse of Cocaine, Amphetamines, Ecstasy and Related Designer Drugs, Freye asserts, "Few substances have received as many severely negative recreational experience reports as has Datura." The overwhelming majority of those who describe their use of Datura find their experiences extremely unpleasant ─ both mentally and often physically. However, anthropologists have found that indigenous groups, with a great deal of experience with and detailed knowledge of Datura, have been known to use Datura spiritually (including the Navajo and especially the Havasupai). Adequate knowledge of Datura properties is necessary to facilitate a safe experience. The ancient inhabitants of what became central and southern California used to ingest Datura to "commune with deities through visions". The Southern Paiute believe Datura can help locate missing objects. In ancient Mexico, Datura also played an important role in the religion of the Aztecs and the practices of their medicine men and necromancers. It was reportedly used by the Aztecs for ritual sacrifice and malevolent purposes as well. In modern-day Mexico, some datura species are still used for sorcery and other occult practices, mostly in the southern region of Veracruz, specifically in the city of Catemaco.

Bernardino de Sahagún, in around 1569, called attention to Datura in these words: "It is administered in potions in order to cause harm to those who are objects of hatred. Those who eat it have visions of fearful things. Magicians or those who wish to harm someone administer it in food or drink. This herb is medicinal and its seed is used as a remedy for gout, ground up and applied to the part affected."

Christian Rätsch has said, "A mild dosage produces medicinal and healing effects, a moderate dosage produces aphrodisiac effects, and high dosages are used for shamanic purposes". Wade Davis, an ethnobotanist, also lists it as an essential ingredient of Haitian zombie potion. In Western culture, the same species (Datura stramonium) has been said to have been commonly used by witches as an ingredient for their flying ointments and was regularly included in detailed recipes of magical ointments dating back as far as the early modern period, predominately in New England and Western Europe. During the anti-witchcraft hysteria of colonial times it was considered unlucky or inappropriate to grow D. stramonium in one's garden due to its supposed reputation for aiding in incantations.

title: Datura


text:
Commutator subgroup

In mathematics, more specifically in abstract algebra, the commutator subgroup or derived subgroup of a group is the subgroup generated by all the commutators of the group.

The commutator subgroup is important because it is the smallest normal subgroup such that the quotient group of the original group by this subgroup is abelian. In other words, $$G/N$$ is abelian if and only if $$N$$ contains the commutator subgroup of $$G$$. So in some sense it provides a measure of how far the group is from being abelian; the larger the commutator subgroup is, the "less abelian" the group is.

Commutators
For elements $$g$$ and $$h$$ of a group G, the commutator of $$g$$ and $$h$$ is $$[g,h] = g^{-1}h^{-1}gh$$. The commutator $$[g,h]$$ is equal to the identity element e if and only if $$gh = hg$$, that is, if and only if $$g$$ and $$h$$ commute. In general, $$gh = hg[g,h]$$.

However, the notation is somewhat arbitrary and there is a non-equivalent variant definition for the commutator that has the inverses on the right hand side of the equation: $$[g,h] = ghg^{-1}h^{-1}$$ in which case $$gh \neq hg[g,h]$$ but instead $$gh = [g,h]hg$$.

An element of G of the form $$[g,h]$$ for some g and h is called a commutator. The identity element e = [e,e] is always a commutator, and it is the only commutator if and only if G is abelian.

Here are some simple but useful commutator identities, true for any elements s, g, h of a group G:

 * $$[g,h]^{-1} = [h,g],$$
 * $$[g,h]^s = [g^s,h^s],$$ where $$g^s = s^{-1}gs$$ (or, respectively, $$ g^s = sgs^{-1}$$) is the conjugate of $$g$$ by $$s,$$
 * for any homomorphism $$f: G \to H $$, $$f([g, h]) = [f(g), f(h)].$$

The first and second identities imply that the set of commutators in G is closed under inversion and conjugation. If in the third identity we take H = G, we get that the set of commutators is stable under any endomorphism of G. This is in fact a generalization of the second identity, since we can take f to be the conjugation automorphism on G, $$ x \mapsto x^s $$, to get the second identity.

However, the product of two or more commutators need not be a commutator. A generic example is [a,b][c,d] in the free group on a,b,c,d. It is known that the least order of a finite group for which there exists two commutators whose product is not a commutator is 96; in fact there are two nonisomorphic groups of order 96 with this property.

Definition
This motivates the definition of the commutator subgroup $$[G, G]$$ (also called the derived subgroup, and denoted $$G'$$ or $$G^{(1)}$$) of G: it is the subgroup generated by all the commutators.

It follows from this definition that any element of $$[G, G]$$ is of the form

 * $$[g_1,h_1] \cdots [g_n,h_n] $$

for some natural number $$n$$, where the gi and hi are elements of G. Moreover, since $$([g_1,h_1] \cdots [g_n,h_n])^s = [g_1^s,h_1^s] \cdots [g_n^s,h_n^s]$$, the commutator subgroup is normal in G. For any homomorphism f: G → H,

 * $$f([g_1,h_1] \cdots [g_n,h_n]) = [f(g_1),f(h_1)] \cdots [f(g_n),f(h_n)]$$,

so that $$f([G,G]) \subseteq [H,H]$$.

This shows that the commutator subgroup can be viewed as a functor on the category of groups, some implications of which are explored below. Moreover, taking G = H it shows that the commutator subgroup is stable under every endomorphism of G: that is, [G,G] is a fully characteristic subgroup of G, a property considerably stronger than normality.

The commutator subgroup can also be defined as the set of elements g of the group that have an expression as a product g = g1 g2 ... gk that can be rearranged to give the identity.

Derived series
This construction can be iterated:
 * $$G^{(0)} := G$$
 * $$G^{(n)} := [G^{(n-1)},G^{(n-1)}] \quad n \in \mathbf{N}$$

The groups $$G^{(2)}, G^{(3)}, \ldots$$ are called the second derived subgroup, third derived subgroup, and so forth, and the descending normal series
 * $$\cdots \triangleleft G^{(2)} \triangleleft G^{(1)} \triangleleft G^{(0)} = G$$

is called the derived series. This should not be confused with the lower central series, whose terms are $$G_n := [G_{n-1},G]$$.

For a finite group, the derived series terminates in a perfect group, which may or may not be trivial. For an infinite group, the derived series need not terminate at a finite stage, and one can continue it to infinite ordinal numbers via transfinite recursion, thereby obtaining the transfinite derived series, which eventually terminates at the perfect core of the group.

Abelianization
Given a group $$G$$, a quotient group $$G/N$$ is abelian if and only if $$[G, G]\subseteq N$$.

The quotient $$G/[G, G]$$ is an abelian group called the abelianization of $$G$$ or $$G$$ made abelian. It is usually denoted by $$G^{\operatorname{ab}}$$ or $$G_{\operatorname{ab}}$$.

There is a useful categorical interpretation of the map $$\varphi: G \rightarrow G^{\operatorname{ab}}$$. Namely $$\varphi$$ is universal for homomorphisms from $$G$$ to an abelian group $$H$$: for any abelian group $$H$$ and homomorphism of groups $$f: G \to H$$ there exists a unique homomorphism $$F: G^{\operatorname{ab}}\to H$$ such that $$f = F \circ \varphi$$. As usual for objects defined by universal mapping properties, this shows the uniqueness of the abelianization $$G^{\operatorname{ab}}$$ up to canonical isomorphism, whereas the explicit construction $$G\to G/[G, G]$$ shows existence.

The abelianization functor is the left adjoint of the inclusion functor from the category of abelian groups to the category of groups. The existence of the abelianization functor Grp → Ab makes the category Ab a reflective subcategory of the category of groups, defined as a full subcategory whose inclusion functor has a left adjoint.

Another important interpretation of $$G^{\operatorname{ab}}$$ is as $$H_1(G, \mathbb{Z})$$, the first homology group of $$G$$ with integral coefficients.

Classes of groups
A group $$G$$ is an abelian group if and only if the derived group is trivial: [G,G] = {e}. Equivalently, if and only if the group equals its abelianization. See above for the definition of a group's abelianization.

A group $$G$$ is a perfect group if and only if the derived group equals the group itself: [G,G] = G. Equivalently, if and only if the abelianization of the group is trivial. This is "opposite" to abelian.

A group with $$G^{(n)}=\{e\}$$ for some n in N is called a solvable group; this is weaker than abelian, which is the case n = 1.

A group with $$G^{(n)} \neq \{e\}$$ for all n in N is called a non-solvable group.

A group with $$G^{(\alpha)}=\{e\}$$ for some ordinal number, possibly infinite, is called a hypoabelian group; this is weaker than solvable, which is the case α is finite (a natural number).

Perfect group
Whenever a group $$G$$ has derived subgroup equal to itself, $$G^{(1)} =G$$, it is called a perfect group. This includes non-abelian simple groups and the special linear groups $$\operatorname{SL}_n(k)$$ for a fixed field $$k$$.

Examples

 * The commutator subgroup of any abelian group is trivial.
 * The commutator subgroup of the general linear group $$\operatorname{GL}_n(k)$$ over a field or a division ring k equals the special linear group $$\operatorname{SL}_n(k)$$ provided that $$n \ne 2$$ or k is not the field with two elements.
 * The commutator subgroup of the alternating group A4 is the Klein four group.
 * The commutator subgroup of the symmetric group Sn is the alternating group An.
 * The commutator subgroup of the quaternion group Q = {1, −1, i, −i, j, −j, k, −k} is [Q,Q] = {1, −1}.

Map from Out
Since the derived subgroup is characteristic, any automorphism of G induces an automorphism of the abelianization. Since the abelianization is abelian, inner automorphisms act trivially, hence this yields a map
 * $$\operatorname{Out}(G) \to \operatorname{Aut}(G^{\mbox{ab}})$$

title: Commutator subgroup