text:
Talk:Exergy

Needs more focus
Just a reader leaving a quick note here: Thanks for writing! However, the article seems to jump around excessively. The core concepts should be brought into the front, in a concise form, before going into the ramifications... (just my 2 cents) —Preceding unsigned comment added by 71.139.177.7 (talk) 04:47, 29 May 2010 (UTC)

I'm another reader (from a biological background) trying to distinguish the terms "free energy", "available energy" and "exergy". There is a lot of good stuff here, but I note that there are still a number of loose ends in main text from work started in 2007 that sill hasn't been cleaned up. I had enough physics as an undergraduate to understand some of the issues, but not enough that I can tidy up the unfinished business. Thanks. —Preceding unsigned comment added by 124.180.182.165 (talk) 23:23, 2 March 2011 (UTC)

The article is a mess because Exergy is a mess ! Using Exergy (or Entropy) for thermodynamics is fair enough, but attempting to use it in Economics - i.e. saying that high Exergy efficiency is good and low Exergy efficiency is bad - is somewhere between dangerous and wrong! — Preceding unsigned comment added by 193.34.187.245 (talk) 13:43, 4 April 2018 (UTC)

Finite exergy?
What happens when there is no exergy left? Is there a way to prevent this?? —Preceding unsigned comment added by 67.53.37.220 (talk) 08:00, 16 April 2009 (UTC)

Rewrite in progress
I found one or two articles about this and emergy and energy quality that actually seem to make sense to me and seem to contain something approaching rigor. So I'm doing a rewrite starting with exergy because it's the oldest and most rigorous concept. Flying Jazz 12:00, 28 December 2005 (UTC)

Merge
I suggest that we merge the energy quality article with this article, and develop a clearer statement of the two. Sholto Maud 05:53, 4 December 2005 (UTC)

 * That's a really bad idea. From what I can tell, exergy has been around since the 1800s, emergy is a pretty recent concept and it might turn into an important concept, and "energy quality" relates the two using a really awful term instead of the better term of transformity. This seems like important stuff and it needs to be presented separately and presented well so that both scientists and laymen can distinguish between what's been used for power plant designs for generations (available energy=exergy) and a promising protoscience that started out being a little goofy. Flying Jazz 11:56, 28 December 2005 (UTC)

 * Now that I've gotten wrapped up in writing this thing, I see that energy quality might not be such a bad term.  Oops. But I do think things should be presented separately.  Flying Jazz 01:48, 2 January 2006 (UTC)

Comment
The sentence:
 * This work potential is due to either a potential due to a force, temperature, or the degree of physical disorder.

Needs rewording, but I can't figure out how to fix it.RJFJR 22:27, Feb 12, 2005 (UTC)

RJFJR, I attempted to help - Wes, Aug 15, 2005

Is there a 2nd Law of Efficiency?RJFJR 22:27, Feb 12, 2005 (UTC)

Do you mean: Is there a 2nd law efficiency? Yes, as defined in "Thermodynamics - An Engineering Approach" 4th edition, by Cengel and Boles (2002), p.400: "...we define a second-law efficiency ηII as the ratio of the actual thermal efficiency to the maximum possible (reversible) thermal efficiency under the same conditions: ηII = ηth / ηth,rev" This is a concept I used quite extensively in the exergy analyses in my PhD thesis. I found it to be a more "true" representation of the energy conversion efficiency - it compares the system with the best possible (reversible) performance. Davo100 03:18, 27 March 2007 (UTC)

formulas
There are two fomulas listed under Exergy of heat available at a temperature, one is for heat into an object and one for heat out of an object. They both have terms that amount to Tc/TH. Can they be combined into one formula and ignore whtehr the object is warmer or colder than the environment? RJFJR 05:27, Feb 19, 2005 (UTC)

I think the same. B = Q(1-Tr/Tsource) shall we edit ? --Napishtim (talk) 14:07, 16 December 2007 (UTC)

I see this equation change was made, but nowhere in did I find a definition for Q —Preceding unsigned comment added by 158.12.37.51 (talk) 17:17, 24 March 2011 (UTC)

Availability
Question: Is the exergy the same thing as the thermodynamic Availability function,
 * $$A = E - T_R S + P_R V - \mu_R N\,$$

where changes in A correspond to changes in the amount of useful work that can be extracted from a system with respect to an reservoir of infinite capacity at temperature TR, pressure PR and chemical potential μR ?

(Reference: Waldram, Theory of Thermodynamics, pp. 75, 205). -- Jheald 11:24, 5 December 2005 (UTC)

 * Looks the same to me. The rewrite is making this clear Flying Jazz 11:56, 28 December 2005 (UTC).

 * When I see A, I think of Helmholtz free energy, but I think some people use F for helmholtz, and those might be the same people that use A for availability (which is another name for exergy). Just to confuse things more, the helmholtz page relates helmholtz to availability too when temperature doesn't change. Also, some people the past used B to indicate any thermodynamic potential (where I've used X). But the short answer to your question is yes. Flying Jazz Flying Jazz 22:02, 30 December 2005 (UTC)

Cumulative Exergy
I'd like to suggest that there is a separate sub-section dedicated to the concept of "Cumulative Exergy" as it is used in engineering. And then another sub-section dedication to a consideration of whether the engineering application of "Cumulative Exergy" is formally analogous to the application of "emergy" in systems ecology. Sholto Maud 03:03, 10 January 2006 (UTC)

 * I think the rigor of the emergy concept should be discussed in the emergy article. This article might discuss cumulative exergy eventually in a little more detail in the context of changing a reference state or unifying multiple reference states to an earlier one. In general though, cumulative exergy loss (or gain) is just like cumulative money loss/gain, cumulative weight loss/gain or cumulative heat loss/gain, so it's not worth a separate section in my opinion. Flying Jazz 16:49, 10 January 2006 (UTC)

 * Re: emergy... agreed.
 * Re: cumulative exergy. 1. So can we assume that the cumulative exergy concept is mathematically the same no matter whether it is used by engineers, biologists, chemists or ecologists? 2. If consequence of irreversible cycle is cumulative exergy loss, does a reversible cycle have the consequence of cumulative exergy gain? Sholto Maud 06:33, 11 January 2006 (UTC)

 * 1. I don't know about that yet, but I suspect there won't be a simple yes/no answer to that question. 2. No. Exergy=available energy. That would mean available energy appearing out of nowhere. For a reversible cycle, there is no change in exergy. Flying Jazz 13:19, 11 January 2006 (UTC)

 * Thank you for your response Flying Jazz. You might be interested in the anonymous quote I have put up at Talk:Emergy. If my anonymous source (apologies for this anonymity) is right then it seems that emergy algebra and cumulative exergy algebra are one in the same. Iff this is the case, then cumulative exergy algebra appears to address the phenomena of "coproduction". Sholto Maud 22:25, 11 January 2006 (UTC)

 * Cogeneration is nice. So are other coproduction methods in engineering and in nature. Your anonymous source has told you that integrals are really just like sums. There's no reason to be so strange and mysterious about any of this. If you want more people to understand exergy and emergy concepts, you are going about it the wrong way. This is not ancient Greece and we are not probing Delphic mysteries. When I wrote there probably won't be a simple yes/no answer, I meant that if someone agrees with all the assumptions made then the answer is obviously yes, and if someone doesn't agree with a single assumption made then the answer is obviously no. An encyclopedia article shouldn't make that judgement for the reader in my opinion. Please show your source what I have written under the "Applications" section. This is not yet referenced and it's a first draft, but I think I can come up with support for most of the statements I've made. I'm curious whether you or your source or others find this section to have a neutral point of view as it proceeds from engineering to the cosmological argument. Flying Jazz 00:06, 12 January 2006 (UTC)

 * My apologies if I am going about this the wrong way, and it seems mysterious - I have not been well schooled in diplomatic emergy synthesis. But also I don't want to make stupid errors, so I go slow. :)
 * Re: Yes/No - I understand.
 * Re: Show my source - I'll refer them to the section, to be rigorous, I understand it is a draft, but, as you suggest, I think that the section should be very well referenced, with actual practical examples.
 * Re: Neutrality & general comments - there are a few comments which I feel hesitant about, but let me say that I think you have done some fantastic work so far, and I appreciate your contribution very much.
 * - Not sure if saying, "The combination of untestable hypotheses, unfamilar jargon that contradicts accepted jargon, intense advocacy among its supporters, and some degree of isolation from other disciplines have contributed to this protoscience being regarded by many as a pseudoscience." is neutral.
 * - Not sure if saying, "Testing this idea in living organisms or ecosystems is impossible for all practical purposes because of the large time scales and small exergy inputs involved for changes to take place. However, if this idea is correct, it would not be a new fundamental law of nature. It would simply be living systems and ecosystems maximizing their exergy efficiency by utilizing laws of thermodynamics developed in the 19th century." is neutral. I'd like to refer you to Bastianoni's article. It seems to me that $$k_iCE$$ in Figure 1 is an example of exergy flow using the energy systems language in biochemistry and biophysics. And also perhaps, this book might be good read as an example of testing the maximum power hypothesis.
 * - Rather than say, "There has been some progress in standardizing and applying these methods." it might be better to give examples of the progress.
 * The intensity of my emergy/cumulative exergy advocacy will reduce as this year proceeds. Good luck with this important work. Best Regards, Sholto Maud 23:09, 12 January 2006 (UTC)

You may be right about many of those comments. As I learn more (and relearn more of what I knew in college), I'll try to keep your comments in mind. However, your own statement about the energy systems language being important in that article does seem to support my statement that a problem many have with these fields is unfamiliar jargon to describe topics that are familiar using more standard (or simply older) language. I will consult Odum and his critics a little later after the math and engineering sections have a few examples in them. Don't worry. The guy won't be ignored when the article is done. Flying Jazz 23:11, 13 January 2006 (UTC)

1911 Britannica
The 1911 Britannica article "Energetics" is of quite interesting historical value for this page. As well as a good survey of how the concept of Available Energy developed, clarified and then took hold during the 19th Century, particularly noting the work of Rankine and Kelvin in the 1850s, it's also of interest for showing that circa 1911 the concept of Available Energy seems to have been seen (at least by the author) as very much the best way to think about the efects of the Second Law. The original article is notably clearly written and reads very well. Unfortunately, however, none of the characters used for variables has been OCR'd at all well, which makes most of the scanned version sadly hard to follow. The original printed text is well worth looking out, however.

 * Also relevant for the energetics page! :) Sholto Maud 06:35, 11 January 2006 (UTC)

Free energy
Would there be any merit in combining the exergy article with the free energy article? They are almost identical in their definitions? Sholto Maud 00:45, 18 February 2006 (UTC)

 * No. In that case they should be edited to make them more different.  Exergy = Availability.  Free Energy = {Gibbs, Helmholtz} Free Energy.  Of course, Free Energy can be derived as a special case of the Availability function.  But IMO, discussion of exergy/availability under Free Energy shouldn't go much beyond that.

 * The two concepts are different, and usefully treated as such. If the articles have become too close to each other then some cutting back again to separate them is required. IMHO. -- Jheald 04:54, 18 February 2006 (UTC).

 * I agree with Jheald. The concepts are different and are used for different purposes and exergy should be understood on its own merits instead of being merged with other concepts.  That little subscript to indicate reference conditions makes a huge difference to everything!  By the way, I still regard this exergy article as incomplete and messy, and I wasn't the one who removed the tag.  Especially with respect to conservation issues, I think it's important that detailed and technically accurate information about this topic is "out there" online freely accesible to people.  My enthusiasm for the topic hasn't decreased, but getting done the first few sections took up too much of my time and I couldn't continue at that pace.  I hope to come back to this article in a few weeks and add examples and implications in text boxes and diagrams.  As it is right now, this article makes a lot of statements that I'm not sure should be included as written even though I wrote it but I hope to make detailed references with a copy edit at that time too. Flying Jazz 13:05, 18 February 2006 (UTC)

 * Ok cool. For one, I appreciate the attempts to clarify these concepts. If I may be useful as resident fool my summary is;
 * Reference conditions is what makes exergy different from free energy: exergy is applied to systems with a large scale reference environment, free energy is applied to systems with a small/no scale reference environment.?
 * When it says, "Unlike energy which is always conserved for a cyclic process, an irreversible cycle reduces exergy." is it correct to say that a simple electrical circuit with resistor and battery is an example of this, such that the electrical energy is conserved in the circuit/cyclic process, but the chemical energy driving electron flow is not conserved and is a non-cyclic (irreversible) process where "exergy is reduced" or lost as heat accross the resistor? Such a circuit seems to involve free energy but are the reference environments for exergy and free energy different or the same in this example? Sholto Maud 13:31, 18 February 2006 (UTC)

 * Didn't Socrates always pretend to be a fool at first...and then he started asking questions too... The reference conditions are what makes exergy different from every thermodynamic potential, including free energy. Exergy is applied by comparing a system to a reference environment.  It says what the system can do, what work it can perform, before it can't do any more because it just blends in with a reference environment that doesn't change because the event took place.  Free energy is only a property of the system and the environment is not involved in any way.  Free energy doesn't compare the system to anything else. If you have a mix of chemicals in an isolated box, you can use free energy to determine whether a reaction will occur.  There is a "before" and an "after" state for the contents of the box.  But in order to use the exergy concept properly, there has to be something else either inside or outside the box that acts on or gets acted on by the reaction.  Still, I think in many situations, free energy and available energy can be used as if they were the same thing when they are set equal to each other (see equation 6 and 7 in the current version of the article).  There might be some confusion about the math as it is now because the free energies of formation for chemicals are often listed in tables with respect to forming that chemical at 25 °C from elements at the same temperature, and the subscript 0 is used to indicate a "standard state" at a certain T and P, but this is different from "reference environment" in the exergy concept.  I changed the math in the article to "R" subscripts to reflect this and match the second law of thermodynamics article.
 * I'm not sure what you're asking exactly about the battery, but maybe the answer is in the last paragraph of the the Mathematical Description section. Flying Jazz 14:40, 18 February 2006 (UTC)

 * That explains alot, thanks Flying Jazz. I was really confused about the difference between this and free energy as well. So basically, free energy is the energy released during a reaction and exergy is the energy released ifa system shifted to the energy level of the surroundings? BTW, the 0 suffix is 25 degree C, 1 atm. kr5t

Re: Energy quality types
The article says that (A) "if there is an energy transformation, the second principle of energy flow transformations says that this process 'must involve the dissipation of some energy as heat'. Measuring the amount of heat released is one way of quantifying the energy, or ability to do work and apply a force over a distance".

The entropy (second principle of energy flow transformations) article says (B) ""Ice melting" - a classic example of entropy increasing".

If A & B, then ice melting (as an example of entropy increasing) must involve the dissipation of some energy as heat. How does one measure the heat released when ice melts? (or would it be neg-exergy? Sholto Maud 05:34, 11 May 2006 (UTC)

I think one should look at Entropy as a measure of energy diffusion. At first in your ice cube, you have a temperature difference with the environment, which is then an energy difference. As ice melts, energy tends to be homogeneous in the system : entropy increases. Then, the sentence you mentionned is not exact. --Napishtim (talk) 14:21, 16 December 2007 (UTC)

B or ψ or Ξ or X?
These are the four letters I've seen used for exergy. I know that B is a magnetic field strength (units of tesla), so using B for exergy (units of joules) might confuse people. I want to use it anyway because my experience has been that the texts that refer to exergy most often and the most authoritatively (Szargut's "Exergy Method: Technical and Ecological Applications" is handy now) have used B and that's what I learned as a chemical engineer, so I'm reverting the introduction. E is an electric field strength (units of newtons per coulomb) and also energy (units of joules). Physicists seem used to this. The thermodynamics folks and the field folks should be used to having conflicting nomenclature by now, and these two subfields of physics don't interact often enough for it to be too much of a problem I think. Flying Jazz 06:46, 29 June 2006 (UTC)

 * Looks like it's called φ sometimes also. Flying Jazz 07:05, 29 June 2006 (UTC)

 * If I read the 2nd law article correctly and it's a thermodynamic potential, in statistical mechanics it's usually denoted as Ξ. --0SpinBoson 13:44, 29 June 2006 (UTC)

 * Exergy+"Statistical mechanics" receives 888 google hits. Exergy+ecosystem gets about 25,000. Exergy+physics receives about 50,000. Exergy+engineering gets about 120,000.  The concept is used most often by engineers, so I'm reluctant to use the statistical mechanics variable. I also don't think putting subscripts and superscripts on a Ξ looks right but maybe that's just me. Maybe I shouldn't have asked for help on the physics project talk page after all, but I would like to have rigorous math here before writing more about less rigorous subtopics, and I'd like to put the same letter on the 2nd law page. Flying Jazz 15:12, 29 June 2006 (UTC)

 * As long as you're consistent, it doesn't matter much I suppose. Just one of those things, like i vs. j for electrical circuits. --0SpinBoson 15:26, 29 June 2006 (UTC)

 * I found a good powerpoint presentation about this issue comparing 15 textbooks (with a silly joke in the middle). Their recommendation for textbooks was to use an "E" with a different font type, like normal Roman E for exergy instead of italic E for energy. However, they didn't say whether any of the textbooks they examined did this. Flying Jazz 15:12, 29 June 2006 (UTC)

 * When I did thermo it was A, for Availability; but IUPAC says that now has to be Free Energy Helmholtz Energy. Ξ was the Grand Partition Function, ie the partition function for a system with a variable number of particles.  I can't say I like B, because in physics there's almost always the chance of a magnetic field knocking around somewhere.  So that's why I used X in the second law article -- that and the fact that it seemd a nice everyday unthreatening sort of letter, and didn't seem to be taken by anything much else. Jheald 15:23, 29 June 2006 (UTC).

 * All four should be mentioned in the Exergy article, and perhaps also the 2nd law page. I have no preference as to symbol. In the absence of IUPAC standard, the idea that the most used symbol (in this case engineering useage) can be a proxy-standard seems to have merit. Sholto Maud 08:52, 30 June 2006 (UTC)

 * What was Zoran Rant's symbolism again? Perhaps the article should track the historical development (and changes) of the symbols: who used which one for what purpose... were they trying to emphasise something different with a different symbol or were they not aware of precedent symbols

 * I study energy eng. in italy..we have always used the &Xi according to Kotas..

Cold exergy
The statement on "cold exergy" is incorrect.

X/Q = 1-To/T is valid even if T < To. The numerator and denominator do not magically reverse in this case. However, the signs of energy and exergy are now opposite, indicating they flow in opposite directions.

The thermal exergy of a substance below the reference temperature can have an absolute exergy greater than the energy it contains if the temperature is less than half of the reference temperature (absolute scale). Don't worry, the amount of energy flowing in at the reference temperature is still greater than the numerical value for the exergy.

If you don't get to it, i'll change it when I have time.

Wes Hermann 04:18, 3 December 2006 (UTC)

I agree whith this, I changed the article. Further explanations are also given.--Napishtim (talk) 14:34, 16 December 2007 (UTC)

How this introduction got screwed up from a simple definition to a contradictory mess
The introduction to this article used to be:
 * In thermodynamics, the exergy B of a system with respect to a reservoir is the maximum work done by the system during a transformation which brings it into equilibrium with the reservoir.[1] The term was coined by Zoran Rant in 1956[2], but the concept was developed by J. Willard Gibbs in 1873.[3]

This was a factual definition of exergy. Then an anonymous user inserted
 * To put it simply, it is a measure of the actual potential of a system to do work. Energy that has a high convertibility potential is high valued exergy (electricity, mechanical work, fossil fuel deliver high valued energy). Reversely, energy which has low convertibility potential is low value exergy (heat close to room temperature). [2] Exergy analysis are used in the field of industrial ecology as a tool to both decrease the amount of exergy required for a process, and use available exergy more efficiently.

No. That is not putting it more simply. That is taking a nice, simple thermodynamic definition of "exergy" that physicists and engineers like and that ecologists should like and running off on the tangent of mentioning "convertibility potential" and adding the word "valued" to turn a definition into a mess. And what the hell is an "actual potential" of something? The actual is one thing. The potential is most likely another. Then User:MGTom added a huge chunk of text to the intro here. It's an introduction!

User:Sholto Maud, to his credit, removed all of that but replaced it with
 * Exergy is defined differently depending on one's point of view (POV). From the thermodynamic POV, exergy is defined as a measure of the actual potential of a system to do work. In the systems energetics POV, exergy has been defined as entropy-free energy, or neg-entropy. It is unclear whether these POV's are compatable.

What the heck? You want an encyclopedia that gives the reader two definitions and then tells the reader that it's unclear whether the two are compatible? That is NOT serving the reader. Exergy is one thing. One concept. If someone in systems energetics says that it is something different from what it is, it is not "unclear." That person is just plain wrong. What is more likely is that Sholto Maud is wrong by overgeneralizing what people in systems energetics say.

The current intro is:

 * Exergy is defined differently in different fields of study. In thermodynamics, exergy is defined as a measure of the actual potential of a system to do work. In systems energetics, exergy has been defined as entropy-free energy. The latter definition is also related to the negentropy concept which aims to measure the work performed by biological systems. It is unclear whether these definitions are equivalent.

Of course they're equivalent. If a process involves doing work by a transfer of energy with no entropic losses, then the maximum possible work done is the same as the work actually done. Energy transferred with no entropic loss could be called "entropy-free energy" by someone who is playing a little loose with words and ideas and probably most rigorous people wouldn't mind as long as their math worked out. Adding negentropy concepts to the introduction was a terrible mistake. Why do this, Sholto? Why take a strictly defined thermodynamic concept and try to obfuscate is as much as possible? Do you think this makes a better encyclopedia to tell people that something is unclear when it's not? I am reverting this introduction to what it used to be when it was clear. Flying Jazz 19:32, 15 November 2007 (UTC)

 * I grant a number of Flying Jazz's points.
 * With respects to obsfucation - what happens if when reading verifiable peer reviewed, and apparently scientific literature, one finds that there is one word (in this case "exergy", but not limited to this case) that is used in different ways depending on the context? Moreover, there is no verifiable peer reviewed, and apparently scientific literature, which explains the difference between the different contexts, definitions and points of view. Result: it is not clear that there is only one definition of exergy, nor is there any natural reason for thinking that any one context or point of view should be considered the standard definition above the other. Whether or not Flying Jazz believes the different conceptions of exergy to be equivalent, and whether or not this is actually true & mathematically provable, this opinion must be published in a verifiable, reputable/peer review scientific publication to be valid content in the article. Flying Jazz has not provided any verifiable reference that supports Flying Jazz's views. Futhermore, with all due respect, Flying Jazz's apparent clarity in fact covers over the reality of the current discourse around the exergy concept. Let the facts speak for themselves - some people use the word "negentropy" in their definition of exergy, while others do not. This is verifiable. But if it is obsfucatory then an obsfucate wikipedia article is an accurate expression of the current state of verifiable affairs. (P.S. Don't forget to provide verifiable references) :) Sholto Maud 22:39, 15 November 2007 (UTC)

 * PPS The intro is now far too long! Should try and keep it to a smallish paragraph.
 * PPPPPS Would a diagram help to illustrate the concept? I found one a while ago, I'll try and mock one up and paste it here for discussion. Sholto Maud 23:55, 15 November 2007 (UTC)

Intro length and article sloppiness
I think it's OK for a complex concept to have a long intro. Most people seem to think that exergy is a more complex concept than entropy (because it's introduced later in textbooks and coursework after students are familiar with entropy), and look at the size of the intro on the entropy article. Much of this article is still sloppy because the most interesting bits are poorly referenced or unreferenced. That's probably mostly my fault for not finishing what I started. I really do hope to be able to come back to it soon. Flying Jazz 04:04, 16 November 2007 (UTC)

Negentropy in the intro
As for the rest of what you are wrote...Sholto...some of the rest of what you posted up there amazes me. Someone who is a fan of negentropy or who discusses negentropy often could use the word "negentropy" in their definition of temperature, of entropy, of energy, of evolution, of cosmology, of multiplication, of Botswana, of fuchsia, or of Venus, and all of that could be verifiable. Do you think that this is a reason for negentropy to be mentioned in the introduction of all of those articles? Maybe you do. Maybe you're just picking on little out-of-way articles like exergy because the introductions to other articles are closely guarded by many editors and you thought you could get away with sticking negentropy into this introduction. And there it sat for about a year. So you were right until I poked my head back in here. Why not read the rest of the article, determine where negentropy would best fit into the bulk of the article, and place it there? If it works then editors like me will probably think it will serve the reader there.

But not in the introduction. Here's why. My "view" is that exergy is a well defined mathematical thermodynamic concept, and that view is supported by references given to Gibbs and to links to MIT open courseware. If your view is that exergy is something else or that there is confusion, then the burden is on you to find similar sources and similar links to the ones that I have provided that define the something-else or expand upon the confusion. But above you wrote "there is no verifiable peer reviewed, and apparently scientific literature, which explains the difference between the different contexts, definitions and points of view." So you can't, and you would be making a huge mistake if you pursue this line of thinking. Wikipedia is for readers who wish to learn things. It is not for you to run around planting negentropy references into introductions for some reasons that other editors can't fathom because you say it's all so unclear. Please don't stroll down that path.

Similar discussions are taking place and have taken place all over Wikipedia for years, and over and over, the person like me who provides links and references to rigorous definitions is seen as supporting the encyclopedia and providing the reader with content of substance that can help them understand difficult material. And the person like you who claims, "There is confusion! There are different contexts! And we must cover the controversy! It's all so unclear! We must tell the reader that it is unclear! It's so unclear that nobody had published anything about why it is so unclear!" is seen as being disruptive. Especially when the article is about a mathematically rigorous science topic that's been described in universities by equations for over a century.

If you are like the other people at Wikipedia who have done this kind of thing before (and many have), then your next step will be to track down the exact verifiable references and statements of a published negentropy fan. Maybe you'll even invite a negentropy fan onto Wikipedia and have them place something on this talk page. I'm not going to follow you down that path. I've spent too many hours arguing in science talk pages with people like that to ever do it again. Learn about the current article first before you contribute to making it more arcane and ambiguous. Read the MIT open courseware. Change the article for the better. Think of a real reader who doesn't know what exergy is, and write for them so they'll understand what it is. Don't imagine a mythical reader who learns about things by discovering that there is a lack of clarity. That reader exists only in your mind and in the minds of people who have typed similar things into talk pages and disrupted Wikipedia in the past. Write for the real reader, not that fantasy-land reader. If you don't write for the real reader, if you do anything else, anything else, even here on the talk page, I will consider it to be disruptive to Wikipedia and I'll begin to take steps to stop it immediately with no additional warning. If the diagram you're thinking of posting here fits the article and the reality of the rigorous thermo definition of exergy, then bring it here, add it to the article, write about it. You don't even need to talk about it in the talk page. If the diagram you're thinking of posting here does not meet that description, don't bother posting it because I won't bother discussing it. Flying Jazz 04:04, 16 November 2007 (UTC)

Exergy diagram
I table the exergy diagram (previously mentioned) for discussion. ... I'm not sure I've got the energy systems language analog right though Sholto Maud 10:00, 16 November 2007 (UTC)

 * Something similar to the top diagram must be in the article eventually because there are diagrams like that in the exergy literature over and over using numerical values. The confusing things (for me right now because I need a refresher course on this topic) is that the use of the subscript "0" in that top diagram seems to sometimes refer to "reference conditions" in the sense of "standard conditions" (like for H-H0 to the left) and sometimes to "reference conditions" in the sense of "environment conditions" (like when T0 appears). I also suspect that all of the terms must be differentials in order for this diagram to reflect the physics in a general sense. Simple processes would result in logarithms being involved being involved instead of (T-T0)/T in the final term on the top right of your diagram. A concrete example is given in http://www.mdpi.org/entropy/papers/e3030116.pdf . Someone (with a formal science or engineering background) needs to look over that paper or another paper with a concrete example and try to write something general and relatively simple for the Wikipedia reader. As for "energy systems language" and the bottom diagram, I don't know anything about it (yet) other than the fact that arrows point to and from the same boxes but an 8 year old could tell you that. Please don't incorporate the diagram into the article yet. It leads to more questions than answers with the current version of the article. Flying Jazz 14:37, 16 November 2007 (UTC)

 * Ok, thanks for your comments Flying Jazz. Once formal scientists or engineers have made comment on the top diagram, I can re-do it according to their specifications and leave out the energy systems language analog at the bottom. But I couldn't work out where entropy fitted in though, looks like I also need a refresher course on this topic. -- Sholto Maud (talk) 21:39, 16 November 2007 (UTC)

 * This diagram is more valuable than the whole of the main article - surely it can be refined by someone who understands the subject and included? — Preceding unsigned comment added by 193.34.187.245 (talk) 14:03, 4 April 2018 (UTC)

Combination property
There might be a problem with different people having different definitions for exergy.

From what I can deduce from my 2008 text book, the exergy of a system, depends not only on the system but also on its environment. Hence for example the polar ice caps currently have exergy, since they are melting.

If the earth cooled down a little bit and they stopped melting, they would again be in equilibrium and suddenly loose their exergy.

It is kind of like the concept that Joe System is richer than Bill Environment, at least right now.

If Bill Environment suddenly gets more money, then Joe System is no longer richer than Bill Environment, so Joe being in a state of richer is a combination property. This seems to me different than a state property which would be how much money Joe System actually has.

Seems like a poorly defined concept to me, unless I can nail it down in terms of a difference between thermodynamic potentials but even then it is hard to know which potential to pick, with the Gibbs free energy being the best candidate???

My thermodynamics text book shockingly does not have either Gibbs free energy or Hemlmoltz free energy in its index, but seems to have devoted an entire chapter to this new exergy buzz word.

I can supply more quotes later, but what I wanted to ask is, I have now taken the liberty of changing the definition of exergy, because before it was relative to some reference state which since it was a reference state was assumed to be constant, unlike the idea of an environment which can be changing with time. My text definitely says relative to an environment, not a reference state. —Preceding unsigned comment added by Hobojaks (talk • contribs) 20:43, 23 December 2008 (UTC)

Removing the section Comparison of energy and exergy, for now
This discussion refers to the section Comparison of energy and exergy as it was in the article revision of 18:39, 20 July 2009; I removed this section in the very next revision, and will now discuss why.

The section consisted of a comparison table followed by a short paragraph. The comparison table had two headings, “Energy of a system is...” and “Exergy of a system is...”, and in particular it included the following two dubious entries: “Energy of a system is... its ability to produce motion” whereas “Exergy of a system is... its ability to produce work”; and “Energy of a system is... different from zero (E=mc2)” whereas “Exergy of a system is... equal to zero when at equilibrium with the environment”.

The paragraph following the table read:

 * Exergy is a measurable value that is decreased during the conversion of useful energy to useless energy. Therefore, exergy measures the actual potential of a system to do work. The exergy consumed to create something, a product or service, is more than the work done to create it. Exergy is the work that can no longer be done elsewhere because the economic good was made. Exergy has been described as a measure of energy quality because of these traits.

While a section like this is a good idea in principle, there are a number of reasons why it should not stay in the article in its present form. My main concern with it is that it seems to me to be potentially very misleading or confusing, as I will explain shortly. Unfortunately, I myself don't know how to fix it, and so, to prevent the spreading of confusion, I decided to remove it, for now. But I also have a more formal reason for removing it: it is almost completely unsourced. True, it does have one reference, but the article in question ('“On an absolute thermometric scale”' by Kelvin himself) has very little to do with the subject-matter of this section. For example, Kelvin's article quite obviously cannot be a source for anything having to do with E=mc2, as it was written more than half a century before Einstein came up with that equation. Also, it is clearly not saying anything about products, services, or economic goods. More critically, the word 'energy' does not even appear in the article!

Apart from issues of sourcing, a number of statements in this section are potentially very confusing. Let's start with the statement that “Energy of a system is… its ability to produce motion” as opposed to exergy of a system, which, the section says, is “its ability to produce work.” Now exergy clearly does have something to do with work. However, on the face of it, the statement about energy being the ability to produce motion rather than work is highly problematic. Every elementary textbook defines energy as “the ability to do work,” and for what seem to be good reasons: kinetic energy is equal to the work that would have to be done by a net force to accelerate the object from rest to its current speed, whereas the difference in potential energy (which is necessarily due to a conservative force field) at two locations is equal to the work that has to be done against the force field to move the object from one location to the other (such that the kinetic energy is the same at the beginning and at the end); these definitions do not change in more advanced treatments of classical mechanics. Any statement that would deny these reasons (for saying that energy is the ability to do work) is surely a bit suspect, and is probably simply a case of an author not expressing him- or herself well. True, energy must be expended to set something in motion, but then again, sometimes energy must be expended simply to change the configuration of something (which has to do with the object's potential energy). For example, it takes energy to compress a spring or to form chemical bonds in a nitroglycerin molecule. In short, whatever the nature of the distinction between energy and exergy that the author was attempting to elucidate here, the text as written fails to explain it.

(In quantum mechanics things are trickier, and we usually don't talk about work; but things are also tricky as far as the concept of “motion”. For example, in what sense does the electron, when in an eigenstate of hydrogen atom, “move”? However, the quantum mechanical conundrums are probably irrelevant to the present discussion, which is concerned with macroscopic phenomena only, and whatever quantum mechanics says must, at macroscopic scales, be indistinct from what classical mechanics says; see the article on the correspondence principle.)

Next, since this article is hardly the place to treat relativistic thermodynamics, let's not mention E=mc2. Invoking it in the present context is useless, since the relevant microscopic theories for the purposes of this article are clearly classical Newtonian mechanics and (perhaps) nonrelativistic quantum mechanics. So if one is doing a comparison between energy and exergy, one should first do it in the framework of those theories. If there is something interesting to be said about exergy in relativistic thermodynamics, that surely merits at least a separate section.

Further, regardless of whether one wants to include E=mc2 in the total energy, it is simply not true that energy must be different from zero. After all, some of the energy in the system might be potential energy due to an external force field. (The zeroth component of the energy-momentum four-vector, which is what most special-relativity texts mean by “energy,” contains the kinetic and internal energy of the object, but not the energy due to an external force field; see Eq. 7.140 in Goldstein, Poole, and Safko.) And in spatial relativity as well as in Newtonian mechanics, only differences in potential energy due to an external force field have physical meaning. To put it another way, which configuration or location corresponds to zero potential energy is an arbitrary choice. So say you have made a particular choice of which configuration or location of the system under consideration has zero potential energy, and with this choice, it works out that the energy of the system in that state is nonzero. Then I can always chose the zero of potential energy to correspond to a different configuration or location than you did, such that with that choice, the very same system in the very same state works out to have precisely zero energy (I can make it have any other energy, for that matter). And yet, as long as each of us sticks with our choice of where the zero potential energy is, all our subsequent calculations of observable quantities will agree.

In general relativity things are even more complicated. The notion of total energy only makes sense in certain spacetimes (see the articles ADM energy and Mass in general relativity]), and whether energy (and mass) can be negative is an open question (see the article Exotic matter).

Finally, in addition to the comparison table, there was the final short paragraph that talked about services and economic goods. While I am unable to evaluate the quality of this paragraph, it nevertheless seems to me that it has no place in this section. To begin with, the information it is trying to convey is already covered in the section Applications in natural resource utilization. More importantly, however, the present section is meant to be some sort of intuitive, shorthand comparison, a summary, one that can fit into a table format; more extended discussions should be done elsewhere.

For all these reasons, the section in its present form seems quite deeply flawed. I wish I knew enough about exergy to improve it, but I don't. (I do know enough about energy to see that some of the things the section says about energy are dubious at best, as I have discussed above.) Thus, to prevent the spread of confusion and misinformation (about energy, at least) to which the section in the present form would contribute, I am removing the section from the article, for now. Reuqr (talk) 01:18, 13 September 2009 (UTC)

Pictures?
Some pictures would be nice. Narssarssuaq (talk) 06:10, 6 November 2012 (UTC)

Serious flaw
I feel very uncomfortable with the end of the second paragraph: "Exergy is always destroyed when a process involves a temperature change... For an isothermal process, exergy and energy are interchangeable terms, and there is no anergy."

The first sentence is misleading - since exergy can be decreased or increased when changing an intensive variable - and the second is just wrong, which is most easily seen when considering the process of irreversible expansion of a gas through an orifice: There is no associated temperature change - but there is certainly a loss of exergy = anergy.

Has anybody an idea how to correct this flaw? I have difficulties to find suitable references, since the subtle details of this topic are not adequately discussed in most thermodynamics textbooks.

AKoerber (talk) 17:01, 30 May 2013 (UTC)

see "Isothermal? Adiabatic!!!" below

Who uses it? Inquiring minds (our readers) need to know.
The most important thing I want to know about the term exergy is who uses it?

This article badly needs a factual summary of what journals, textbooks, university departments, scientific blogs, etc., use the term.

Someone with access to JStor could search for the term and produce a histogram of uses per year.

Such a section might be branded "original research," but too bad, the information is really needed in this article. Also, such a section could be submitted for publication to a general science journal. American Journal of Physics comes to mind.

207.255.42.202 (talk) 04:12, 18 November 2013 (UTC)
 * We already summarize usages of the term at Exergy. I do not see how graphs of the occurence of this specific word by journal or time would help communicate an encyclopedic understanding of the subject. VQuakr (talk) 04:30, 18 November 2013 (UTC)

Intro too long
The intro is far too long - most of it should be redistributed under headings. However I'm not qualified to fix it myself. 90.198.224.197 (talk) 14:29, 26 August 2014 (UTC)

Isothermal? Adiabatic!!!
In an isothermal process heat would be exchanged if there is a change of fase. There would be a change in exergy. Exergy would remain the same only on an adiabatic process: when there is no heat transfer, not on an isothermal process, when the system does not change it's temperature (but may change it's configuration).

The phrase "Exergy is always destroyed when a process involves a temperature change is wrong. Exergy is always destroyed when there is heat exchange. It does not matter if there is temperature change or not. The author is confusing adiabatic processes with isothermal processes. — Preceding unsigned comment added by 186.26.113.114 (talk) 22:29, 9 March 2015 (UTC)

-- Similarly, in the introduction: "For an isothermal process, exergy and energy are interchangeable terms, and there is no anergy." The comment above "Serious flaw" comments on roughly the same thing. I believe the relevant qualifier is an isentropic process (an adiabatic process can still be irreversible and reduce exergy, like a shock wave in fluids). In the introduction, I've made the change from istothermal to isentropic. I don't think it can be wrong, because entropy increase and exergy reduction are linked.

Incorrect first sentence
The first sentence is plain wrong. Exergy is the maximum useful work during a process that brings the system into equilibrium with dead-state at $$(T_0, p_0, \mu_{i,0})$$. The dead-state definition is more than simply a heat reservoir. I suggest this page needs a substantial reworking. RobbieIanMorrison (talk) 22:10, 16 March 2016 (UTC)

Can you explain what the dead state is? If it some choice of reference, could an infinite constant temperature environment be that reference? — Preceding unsigned comment added by 139.47.69.55 (talk) 19:08, 26 February 2021 (UTC)

Why is this an article
The correct term is "available energy". Zoran Rant was pretty much a nobody. Is this term really an accepted term? That needs to be proven or else the article should revert back to the more formal usage. — Preceding unsigned comment added by 107.77.213.225 (talk) 02:24, 8 July 2017 (UTC)

 * It's found on 173 pages of Moran et al., "Fundamentals of Engineering Thermodynamics", so it must at least be a practical engineering concept.

 * However, the current article defines it in the Mathematical Description section as being specific thermodynamic potentials (whose selection depends on the experimental setup and its purpose, I think), but in the Applications section, it gets identified with overarching economic and human goals. The problem is that the precise mathematical definitions of the first section have little intellectual contact with the "big picture" policy speculations of the second section.

 * This is the "Santa Fe transition", where the concept takes mushrooms and gets laid.

 * It is as if the term is being used by two unrelated communities. So I see your point.

 * 2001:171C:2E60:D7E1:1027:D836:13FD:46EF (talk) 00:19, 17 January 2020 (UTC)

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A historical and cultural tangent
The section A historical and cultural tangent is too own-research-y, philosophical, and hand-wavy to be included where it is. It reads like a very high-flying, professorial Apologetic for exergy that only makes sense if you already know the concept very well. Needs rewriting or removal.

2001:171C:2E60:D7E1:1027:D836:13FD:46EF (talk) 00:30, 17 January 2020 (UTC)

- To me, it reads less as pretentious, and more as somebody grappling with the philosophical ramifications of thermodynamics. Although I can sympathize, this Wikipedia article is not the place for it. The sections is based on just bits of the historical and philosophical picture. I propose to remove it completely, and have already removed the final paragraph. It made unsubstantiated claims about ecologists vs physicists calling exergy vs. entropy the more "anthropocentric" principle. I don't buy these supposed perceptions. It also made a lackluster history tangent, swerve towards the meaning of exergy in modern ecology.

Shouldn't time be relevant?
Why are any of energy, exergy, emergy, etc. of any interest if they are diluted by time?

The Carnot cycle is made up of isothermal and isentropic phases. Perfect isentropy requires infinitely fast compression and expansion. Perfectly isothermal phases however require infinitely slow compression and expansion. It can be shown that the isentropic phases of the Carnot cycle exactly cancel, whence the mechanical energy obtainable from the Carnot cycle derives purely from the isothermal phases. But if these happen infinitely slowly then the available power is zero.

Unless exergy takes time into account, I don't see how it is any better than the energy obtainable from the Carnot cycle, which is useless from a power perspective. Vaughan Pratt (talk) 06:55, 8 December 2022 (UTC)

title: Talk:Exergy


text:
Martin Buchan

Martin McLean Buchan (born 6 March 1949) is a Scottish former professional footballer who played as a centre back. Born in Aberdeen, he played for Aberdeen, Manchester United and Oldham Athletic. He also played in 34 international matches for Scotland between 1971 and 1978 including at two World Cups. Buchan later managed Burnley.

Aberdeen
Buchan started his professional career with his hometown club Aberdeen. He captained the team when they won the 1970 Scottish Cup Final 3–1 against Jock Stein's Celtic.

Manchester United
Buchan was signed by Manchester United manager Frank O'Farrell on 29 February 1972 for £120,000, and at the time was the club's record signing. His first game for United came on 4 March 1972 against Tottenham in the First Division. He was unable to prevent United from suffering relegation to the Second Division in 1973–74. However, United bounced back at the first attempt as Second Division champions. Buchan became club captain in 1975 following the departure of Willie Morgan.

Buchan helped United win the 1977 FA Cup Final against Liverpool, which they won 2–1. This meant that Buchan became the only player to captain both Scottish and English FA Cup-winning sides. He also helped United reach another FA Cup final in 1979, where they lost 3–2 to Arsenal. He was still with United when they beat Brighton 4–0 in the replayed 1983 FA Cup Final, but he did not make the team for the final. Buchan left the club in August 1983 after injuries caught up with him, signing for Oldham Athletic on a free transfer. He had played in 456 games, scoring 4 goals, one of which was a superb, yet somewhat uncharacteristic, long-range drive against Everton.

International
Buchan won 34 caps for Scotland, making his international debut in 1971 against Portugal and his last appearance in 1978 against the same country. He played in the 1974 World Cup finals and 1978 World Cup finals and captained Scotland twice: in 1975 against Romania and in 1977 against Argentina.

After playing
On 22 June 1985, Buchan was appointed manager of Burnley, who had just been relegated to the Fourth Division for the first time in their history – 25 years after being league champions. Buchan lasted less than four months at Turf Moor, resigning on 10 October 1985.

Buchan worked for the Professional Footballers' Association (PFA) in Manchester for 17 years before retiring in 2017.

Personal life
Buchan's brother George and father Martin senior both played for Aberdeen, the latter only in unofficial competitions during World War II. His son Jamie played with Aberdeen, Dundee United and Partick Thistle.

As a player
Aberdeen
 * Scottish Cup: 1969–70

Manchester United
 * FA Cup: 1976–77; runner-up: 1975–76
 * FA Charity Shield: 1977

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

title: Martin Buchan


text:
Alex Stepney

Alexander Cyril Stepney (born 18 September 1942) is an English former footballer who was Manchester United's goalkeeper when they became the first English club to win the European Cup.

Early career
Born in Mitcham, Surrey, Stepney had unsuccessful trials with Fulham and joined Tooting & Mitcham United. From there, he was spotted by Millwall, who signed him as an amateur in 1963, but quickly realised his potential and made him a professional within two months of his arrival. Stepney was ever-present for almost three seasons, making 158 appearances, only missing the last game of the 1965–66 season. During this period, he earned three England under-23 caps.

In May 1966, Stepney joined Chelsea for £50,000. Manager Tommy Docherty initially intended to play Stepney and fellow goalkeeper Peter Bonetti in alternate weeks, but just three months later Stepney was sold to Manchester United for a record fee of £55,000, having made just one appearance for the club. With Harry Gregg's career virtually ended by injury, the Manchester United manager, Matt Busby, opted for Stepney after deciding that neither Pat Dunne nor the injury-prone David Gaskell was up to the job. Stepney made his debut for United later the same year against Manchester City at Old Trafford, and he kept a clean sheet as United won 1–0 through a first-half goal from Denis Law.

League and European success
With Stepney in goal, Manchester United won the First Division title in 1967, earning them entry into the European Cup the following season, a competition that no English club had yet won. Stepney featured throughout United's progress to the final at Wembley Stadium, during which he made a memorable close-range save from Benfica striker Eusébio in the closing stages with the score at 1–1. Eusébio was so astonished at Stepney's save that he stopped to applaud the keeper as Stepney threw the ball back into play. United eventually won 4–1 after extra time.

At the start of that season, Stepney had conceded a goal to his opposite number at Tottenham Hotspur, Pat Jennings, in the 1967 FA Charity Shield at Old Trafford. With Tottenham leading 1–0, Jennings punted the ball upfield from the Stretford End; the ball bounced over the stranded Stepney into the net. The game ended 3–3 with United's goals coming from Bobby Charlton (2) and Denis Law.

International recognition
Although a highly talented keeper, Stepney was a distance down the pecking order when it came to the England team. Gordon Banks was the undisputed number one, with Peter Bonetti of Chelsea, Gordon West of Everton and the more experienced Sheffield Wednesday goalkeeper Ron Springett all in Stepney's way. When England qualified for the final stages of the 1968 European Championships, coach Alf Ramsey selected Stepney and West as the two back-up keepers to Banks and, in what turned into a momentous week for Stepney, he made his England debut in a friendly win over Sweden in May 1968, seven days before the European Cup final. England won 3–1.

Ramsey kept Stepney in his thoughts in his preparations for England's defence of the FIFA World Cup in 1970, for which England did not have to qualify having won the previous tournament, but did not give him another cap as the likes of Bonetti and West added to their meagre tallies of appearances. However, when the preliminary squad of 27 was announced, Stepney was in, along with Banks, Bonetti and uncapped rookie Peter Shilton, with no sign of West. When the final 22 who would travel to Mexico was confirmed, Shilton was the goalkeeper sent home.

Nevertheless, Stepney was clearly the third-choice goalkeeper in the squad and the chances of his appearing on the pitch in Mexico were small. When Banks went down with food poisoning prior to the quarter-final with West Germany, it was the slightly more experienced Bonetti – who had six caps to Stepney's one – to whom Ramsey turned, although Stepney did make it onto the substitutes' bench. England squandered a two-goal lead to lose 3–2 and it was Stepney who told the groggy, ill Banks the scoreline in his hotel room by holding up three fingers on one hand and two on the other.

Later Manchester United career
Stepney was occasionally recalled by Ramsey but would ultimately not add to his solitary England cap, with Shilton emerging as the new deputy and ultimate long-term replacement. He continued to play in goal for Manchester United in a period of significant underachievement for the club, which culminated in their relegation to the Second Division in 1974, a season which saw Stepney, unusually for a goalkeeper, score two goals from penalties thus making him the (joint) leading scorer at Christmas. For half a season he was replaced by Jimmy Rimmer. By now, with Stepney's former Chelsea manager Tommy Docherty in charge, they bounced back as Division Two champions the following season (1974–75). During this time, Stepney suffered a freak injury when he dislocated his jaw while barking instructions at his disorganised defence.

The next two seasons saw Stepney as the wise head behind a new, youthful team collated by Docherty courtesy of some astute purchases and a prolific youth set-up. During this period, Stepney had to compete with Paddy Roche for a regular starting position. Stepney was the only player with any Wembley experience at club level at all when United reached the 1976 FA Cup final and the nerves of the youngsters got the better of them as Southampton, a division below United but containing some experienced heads of Stepney's generation, won 1–0. Stepney had no chance with the goal from Bobby Stokes, a late, low, crossfield shot which United claimed fruitlessly was from an offside position.

United reached the cup final again in 1977, against Liverpool, and this time were successful. Stepney got a hand to a bullet shot on the turn from Jimmy Case but could not stop it entering the net and levelling the match after Stuart Pearson had scored for United. Jimmy Greenhoff quickly restored United's lead and Stepney made some good saves in the closing stages as Liverpool, chasing an unprecedented 'treble' of trophies (having already won the league title, and just days later going on to win the European Cup), piled on the pressure.

Stepney was the only player in the 1977 FA Cup winning team remaining from the European Cup winning side of nine years earlier. Stepney was also the last remaining player to play for the club under manager Matt Busby.

Later career
The following year, Stepney was again not an automatic choice, playing 23 of United's 42 games in the League. He played the last of his 546 games for Manchester United in April 1978, prior to leaving for Dallas Tornado in the North American Soccer League in the United States, where he remained until he retired from professional football in 1980.

He kept 175 clean sheets, made a club record 92 consecutive appearances (later broken by Steve Coppell) and, with those two goals, remains United's top scoring goalkeeper. Aside from Peter Schmeichel (who scored in a 1995–96 UEFA Cup game), no other Manchester United goalkeeper has scored in a competitive game for the club after World War II.

Towards the end of his career, he turned out for non-league side Altrincham in the early 1980s, when they were competing in the Alliance Premier League. He helped them win the Alliance Premier League title in 1980–81 (they had won it the 1979–80 season as well), but they did not win promotion to the Football League as the re-election system was still in place and the majority of the league's members voted against them joining the Football League, ending Stepney's hopes of a professional comeback.

Stepney became a goalkeeping coach after he stopped playing, including a spell at Manchester City in 2000–01. He also works as an after-dinner speaker and currently hosts The Legends Football Phone in on 105.4 Century Radio in Manchester, replacing Mickey Thomas – another former Manchester United player.

Style of play
Stepney was never a flashy performer and perhaps his most impressive quality was his positioning, though he could also demonstrate agility when required.

Honours
Manchester United
 * Football League First Division: 1966–67
 * FA Cup: 1976–77; runner-up: 1975–76
 * FA Charity Shield: 1967, 1977
 * European Cup: 1967–68

title: Alex Stepney


text:
Talk:Intelligent Peripheral Interface

Im somewhat unsure of the bandwidth of the various IPI bus standards. The info out there is pretty sparse, but most of what Ive seen suggests 6MB/s for IPI-2 (see Birdsall's Sun Hardware Reference, for instance). Any ideas? - JFinigan

title: Talk:Intelligent Peripheral Interface


text: Category:British fashion designers

title: Category:British fashion designers


text:
Talk:Hanafi school

Vandalism
Is it possible to have a discussion about the vandalism? Someone seems simply motivated to present a negative view of the Hanafi madhab. For every madhab, there are a number of rulings which are distinctive and stand out from the others. For every madhab, there are some rulings which are easier than the others and some which are stricter than the others. For example, Hanafis are also stricter about prayer. Except for hajj, prayers are supposed to be done in their proper time instead of being "liberal" and combining them. And witr is considered to be wajib so a strict Hanafi would actually be praying more often than someone from a different madhab. It isn't Wikipedia's place to say that the Hanafis are wrong.

There has been a lot of anti-Hanafi vandalism on this page it seems. I'm not sure what the best way to handle this is.

 * agreed. these vandals can't seem to accept the fact that other schools of thought have different views from theirs with regard to certain things. such sore losers.

10:21, 27 January 2007 (UTC) The section about where Hanafi adherents are located is a little confusing. I tried to clean up some sentence structure, but I am not familiar enough with the topic to address any more, for fear of changing the meaning. Randomned 20:39, 6 April 2006 (UTC)

Something of the Hanafi methodology should be presented, particularly in contrast to the other schools. The growth and development of the school, from Abu Hanifa and his school, to his two students, Imam Muhammad and Abu Yusuf, and the early alliance of the hanafi school with the state should be mentioned. Also the figure of 45% should be referenced (I couldn't find one yet).EsatErbili 06:10, 16 February 2006 (UTC)

"Northern Egypt is mixed Hanafi/Shafi while upper Egypt and the Sudan are Maliki, Turkey, the Levant (Syria, Lebanon and Iraq are mixed Shafi/Hanafi."

There are two things wrong with this sentence. "Northern Egypt" and "upper Egypt" are the same thing. Everything after Maliki doesn't make sense structurally, and there's no end parenthesis.

"Bosnia-Herzegovina, Albania the Indian subcontinent, amongst the Muslim communities of the Balkans (in Bulgaria and Romania for example) Central Asia (Uzbekistan, Turkmenistan etc) the Muslims of China the Muslims of Russia and Ukraine (Tatars and Turks)."

The above is not a complete sentence.

Also, the article doesn't really flow well from one topic to the next. Zain 22:20, 9 November 2005 (UTC)

 * This article certainly needs work, but "north" doesn't mean "up". As far as I know, "Upper" geographically means "higher", or you can think of it as "upstream", in Egypt's case that's actually south. In any case, the wording is confusing. --Yodakii 01:24, 10 November 2005 (UTC)

 * Upper Egypt does indeed refer to southern Egypt, refrence the Upper Nile among other things. 12.20.127.229 22:23, 21 November 2005 (UTC)

 * I assume that the incomplete sentence and its lack of commas refers to the places that are predominantly Hanafi or follow the Hanafi madhab.

 * Also, where it says "Hanafi is predominant...", the word Hanafi should probably be used as an adjectives to describe those who adhere to the Hanafi school and not the school. Perhaps "The Sunni Muslims in Pakistan and ... are predominantly Hanafi."

 * Also, those places which follow the Shafi school probably should be removed from this article as they are not relevant to the Hanafi school (i.e. "The Kurds of Turkey, Syria and Iraq follow the Shafi school." and also "while Upper Egypt (Southern Egypt) and the Sudan are Maliki.")  Essentially they are off-topic.Pepsidrinka 21:48, 15 December 2005 (UTC)

Blasphemy and Apostasy
The article says blasphemy is not punishable under Hanafi law, but it doesn't mention apostasy. This information would be a valuable addition, particularly with the Abdul Rahman (convert) case so topical; Hanafi law is the default system in the Constitution of Afghanistan, and the Constitution is silent on apostasy. — JEREMY 08:16, 27 March 2006 (UTC)

"An 8th century Somali theologian named Shaykh Uthman bin Ali al-Zeylai wrote the only authoritative text on the Hanafi school of Islam.[citation needed] His book is called the Tabayin al-Haqa’iq li Sharh Kanz al-Daqa’iq. Its four volumes are still in print." -- Perhaps more details needed on this? I've never heard about the person or the book...

Is the Taliban Hanafi?
"it is considered to be the school most open to modern ideas"

Alright, but just to clear this up, wasn't the Taliban a Hanafi group? Or were they influenced by Wahhabism? At any rate, even Wahhabis are not as strict and fannatical as they. Giorgioz 16:03, 2 December 2006 (UTC)

--the Taliban practised an extreme perversion of faith. i'd say they were influenced by the wahhabis, or at least brainwashed by their mulllahs into accepting a pseudo-religion that is nothing like the true, beautiful, infinitely, wonderfully-malleable Islam.

76.108.26.211 (talk) 04:32, 19 November 2009 (UTC)Yes, but it would probably be more useful to say that Afghanistan is a basically Hanafi region.

So...what is it?
The article describes at length the places/cultures in which Hanafi school is predominant and it talks about it being a conservative school of Sunni Islam, but the one thing it fails to do is describe what Hanafi actually is, i.e. what its core beliefs that distinguish it from other schools within Sunni Islam. Can someone with some knowledge on this expand/clean up the article to get this key point across? -- Hux 16:40, 31 January 2007 (UTC)

 * err..i'd suggest you read the article carefully. it's all there, dude. and...hanafism is certainly not conservative, compared to hanbalism or shafiism, for example.

Adherents
Abu Hanifah and the Maturidis say that "Faith neither increases nor decreases" and that "Actions are not a part of faith" has been removed until a valid citation is made. Tabligh Jmaat has been removed from the adherents. They do not adhere to any mazhab. —The preceding unsigned comment was added by Afrazj (talk • contribs).

Isn't it the other way around?
"Faith neither increases nor decreases" and that "Actions are not a part of faith" is the standpoint of the Shafi mzahab and not Hanafi. Imam Abu Hanifa's opinion is that Faith increases and decreases AND actions are part of faith. But obviously I need to provide a proof. In any case I think this statement needs a proof.

What? Where's your source for that? Imam Shafie was famous for his debate with the people of Irja' or the Murjiah, whom believed that action are not part of faith.

In fact, it was well known that Abu Hanifah and Imam Haramain Al-Juwaini held that action are not part of faith, however, there are indications that they both retracted this view latter in their lives. 210.195.104.253 (talk) 07:56, 17 December 2014 (UTC)

reciting quran in languages other than arabic?
someone has claimed in the article that hanafi school allows praying in languages other than arabic which i don't believe is correct, could not verify this anywhere in any source posted or elsewhere. consulted others for advice, this does not appear to be true but if it is it is a unique claim that should definitely provide some documentation for support. for the moment i think it should be removed. —Preceding unsigned comment added by Sawyer207 (talk • contribs) 03:18, 23 June 2009 (UTC)

It is actually half correct. Imam Abu Hanifa indeed believed (used to) that reciting Quran in foreign language was permissible, but he himself (not later scholars) took back his point of view. This is known in the religious jargon as "Raju'", i.e. reverting. I have myself attended one class of the course taught to people as part of becoming a scholar (in Pakistan) and there is in deed evidence in the books taught. Unfortunately, I don't remember the name of the book.

The wikipedia article is incorrect when it says that later scholars overruled the ruling. It was the Imam himself who did Tauba.

Merge
Content was recently merged from Sunni Islam, though the more relevant discussion can be found on that article's talk page. Per Merging, however, I am still required to open a discussion here. I would suggest reading my comments on Talk:Sunni Islam first. MezzoMezzo (talk) 05:38, 9 January 2013 (UTC)

Application today
The article treats the subject of how the Hanafi School was applied several centuries ago, but since it is not applied in that way in Bosnia, Albania, Turkey or India today, it would be interesting and clarifying to read something about its present-day application, written by someone who knows something about it. 81.236.219.119 (talk) 12:03, 9 May 2015 (UTC)

I am a muslim myself and my religion DOES NOT SUPPORT WAR AGAINST DISBELIEVERS JUST BECAUSE OF THEIR DISBELIEF!! This page deliberately presents my religion as a religion of murder and terror. SO I AM REQUESTING TO PLEASE REMOVE THIS PAGE'S FALSE CONTENT and replace it with information found from reliable hanafi muslim scholars.103.230.104.1 (talk) 03:28, 13 November 2015 (UTC)

 * Wikipedia is not a blog, and does not summarize what "I am a Muslim myself and my religion does not or does..." type personal opinions. For why, read WP:WWIN. Study WP:PG for content guidelines. The aim of wiki articles is neither to criticize nor praise Islam, the aim is to just summarize verifiable recent reliable sources, see WP:V and WP:RS for more. RLoutfy (talk) 02:44, 15 November 2015 (UTC)

NPOV issues
Please see Wikipedia talk:WikiProject Islam. Eperoton (talk) 22:38, 21 February 2016 (UTC)

NPOV redux
You may have noticed that the edit summary for removal of the content you have restored included a link to a discussion on a wiki project. You'll have to look in the archives for it now, but the result was a WP:CONSENSUS that inclusion of that material in this article violated WP policy. That means you should not restore it without obtaining a new consensus for its inclusion. I'll summarize the rationale for you here. Per WP:PROPORTION, the coverage of a subject on WP has to reflect its coverage in RSs. There are a number of RSs on the Hanafi school whose scope is similar to this article, such as EI2 (paywall), Iranica, The Oxford International Encyclopedia of Legal History (paywall), The Oxford Encyclopedia of the Islamic World. A selective focus on Hanafi views about certain topics like apostasy, slavery, etc does not reflect how the subject is treated in RSs, and so it violates the relevant policy, WP:NPOV. Instead, these views should be discussed in Apostasy in Islam, Islamic views on slavery, etc, which does reflect how RSs treat those subjects.

Your added material on intoxicating beverages would make a good addition to Khamr, so I'm moving it there. However, there are some issues with it, which I'll take up on the talk page for that article. Eperoton (talk) 14:30, 24 June 2017 (UTC)

Views
It is not very clear what the Hanafi believe. I did not find it during a quick but complete read-through, even though their views should have both their own section and a prominent place (at least a paragraph) in the lead. I don't know anything about the Hanafi or Islam in general, or I would fix this myself: perhaps someone else can take care of it? —Compassionate727 (T·C) 18:13, 28 May 2018 (UTC)

 * What you're looking for is summarized in the section "Sources and methodology", albeit there's room for improvement. Islamic schools of law mostly differ is rather technical aspects of their legal methodology and in various consequences these have on specific rulings. It's difficult to find a concise summary in reputable sources (as opposed to some weak sources which oversimplify the matters). Eperoton (talk) 03:50, 31 May 2018 (UTC)

Criticism on Hanafi fiqh
Please add criticism on hanafi fiqh. — Preceding unsigned comment added by Wikiacc97 (talk • contribs) 13:30, 13 February 2020 (UTC)

Al Andalus and Marocco
Please, correct in the article that Spain and Morocco were and are followers of the Maliki Madhab, except for small groups that follow other schools in present-day Spain. 45.142.46.127 (talk) 17:28, 25 March 2023 (UTC)

Dates
The manual of style outlines that dates can be given in the Hijri calendar when it is relevant, but should be followed by the Gregorian conversion. I think this is a good idea, as the Gregorian dates are relevant in an English language article. I would suggest that phrases such as "the 3rd Hijri century" should be replaced with "the 3rd century AH (9th century CE) throughout this article. Qntmnan (talk) 15:46, 20 October 2023 (UTC)

Improving the Introduction
The introduction for this article could be improved. I think the main questions that need to be answered in the introduction are:

 * 1) What are the sources from which Hanafi laws are derived? (e.g., Hadith, Sunnah, Quran?)
 * 2) What are the acceptable methods by which you should investigate and draw conclusions from those source? (e.g., rational inquiry, analogical reasoning, literal interpretation, diplomatic consensus?)
 * 3) When was Hanafism established, and, briefly, how?
 * 4) What is Hanafism's role in the present day Islamic world?

Some of these points are already covered, but in particular, the first two are not. Also, I think what is there should be condensed, and superfluous information (such as who compiled it) should be moved elsewhere or removed. Qntmnan (talk) 23:20, 22 November 2023 (UTC)

title: Talk:Hanafi school


text:
Kotaro Koizumi

Kotaro Koizumi (小泉 孝太郎) is a Japanese actor and the eldest son of the 56th Japanese Prime Minister, Junichirō Koizumi, and Kayoko Miyamoto.

He studied economics at night classes of Nihon University, but dropped out.

Television

 * Who Wants to Be a Millionaire? – won the maximum ten million yen on a celebrity special
 * Ninomiya Kotaro (Fuji, July 2024) (co-starring with Kazunari Ninomiya)

TV dramas

 * Nurseman (2002)
 * Hatsu Taiken (2002)
 * Shiawase No Shippo (2002)
 * Kurutta Kajitsu 2002 (2002)
 * Home & Away (2002)
 * Boku dake no Madonna (2003)
 * Korogashi Ogin (2003)
 * Igi Ari, Onna Bengoshi Oka Norie (2004)
 * Division 1 \"Pink Hip Girl\" (Fuji TV, 2004)
 * Yoshitsune (2005) – Taira no Sukemori
 * Slow Dance (2005)
 * Tokyo Wonder Tours (2005)
 * Gachi Baka (2006)
 * Attention Please (2006)
 * Fushin no Toki (2006)
 * Haken no Hinkaku (2007)
 * Attention Please SP (2007)
 * Hanayome to Papa (2007)
 * Otoko no Kosodate (2007)
 * Gokusen 3 (2008)
 * Yae's Sakura (2013) – Tokugawa Yoshinobu
 * Age Harassment (2015)
 * Akira and Akira (2017)
 * ''Black Pean (2018) Takashina Gonta
 * The Good Wife (2019)
 * The 13 Lords of the Shogun (2022) – Taira no Munemori
 * Fixer (2023) – Kōji Itakura
 * Black Pean Season 2 (2024) Takashina Gonta

Films

 * Bayside Shakedown 2 (2003) – Shigeru Koike
 * Koshonin Mashita Masayoshi (2005) – Shigeru Koike
 * Kamen Rider Hibiki & The Seven Fighting Demons (2005) – Takeshi
 * Udon (2006) – Udon shop customers
 * Bayside Shakedown 3 (2010) – Shigeru Koike
 * Whistleblower (2019) – Shōhei Nagura
 * You're Not Normal, Either (2021) – Miyamoto
 * The Hound of the Baskervilles: Sherlock the Movie (2022) – Haruto Sutei
 * Oshorin (2023)
 * Rude to Love (2024) – Mamoru

title: Kotaro Koizumi


text: Category:British designers

title: Category:British designers


text:
Wikipedia:Featured article candidates/War of the Spanish Succession/archive1

War of the Spanish Succession
Self nomination. -- Emsworth 22:34, 12 Feb 2005 (UTC)
 * Support Excellent. Phils 23:01, 12 Feb 2005 (UTC)
 * Support. 172 04:04, 13 Feb 2005 (UTC)
 * Support. The article seems brief for such a topic, yet appears to cover it comprehensively. Jeronimo 18:55, 13 Feb 2005 (UTC)
 * Support. Concur with Jeronimo.  Edeans 01:44, 14 Feb 2005 (UTC)
 * Support. Good to see Emsworth back, producing articles of the usual high standard. -- ALoan (Talk) 12:07, 14 Feb 2005 (UTC)
 * Support. I've just gone over it and added considerable detail, so one might want to look again. john k 23:58, 14 Feb 2005 (UTC)
 * Object. If this is supposed to be FA about a war, then it should use the relevant Template:Battlebox, like the one seen on Polish-Soviet War for example. I find the box summary and especially the list of battles very useful. I will support after this is added. --Piotr Konieczny aka Prokonsul Piotrus Talk 12:50, 15 Feb 2005 (UTC)
 * This template was developed for use with battles, not wars, and it is inappropriate to use on articles about wars. I am unconvinced that it is appropriate for the Polish-Soviet War article, and even more unconvinced that it is appropriate here.  I would support the creation of some kind of template specifically for wars, however. john k 15:19, 15 Feb 2005 (UTC)
 * Something for the nascent WikiProject Wars (as opposed to WikiProject Battles)? -- ALoan (Talk) 16:51, 17 Feb 2005 (UTC)


text:
Talk:LZ77 and LZ78

Psuedocode
The pseudocode starts by assigning "prefix" a value that is based on a prefix that is found in the input stream. Unfortunately, "prefix" is never defined in the preceding text, making it impossible to follow the pseudocode algorithm, unless the reader is already familiar with the algorithm or terminology. Can the author please define "prefix" in the introductory text? — Preceding unsigned comment added by Wmagro (talk • contribs) 21:17, 23 March 2019 (UTC)
 * I can't speak on behalf of the author of that pseudocode, but I've revised the pseudocode to address this comment by making the psuedocode match the introductory text. It wouldn't be possible to revise the introductory text to match the pseudocode, as the pseudocode contains a circular-reasoning error as previously written, specifically "prefix := prefix". 65.31.58.24 (talk) 05:08, 6 March 2022 (UTC)

Untitled
Just a question for the author of this article... I am not familiar with the term "Patent minefield", used several times in this article. A wikipedia search for it shows that this is apparently the only article that uses that phrase. I don't object to the phrase really, but it might be good to include at least a brief explanation of what is meant by "patent minefield" or what the implications of being a patent minefield are. --129.15.142.197 22:34, 12 Feb 2005 (UTC)
 * See Software patent. --Damian Yerrick (talk | stalk) 19:01, 9 October 2007 (UTC)

LZ78 Example
I've added a (hopefully pretty thorough) example of the LZ78 algorithm. I'd be grateful if someone other than me could give it a checking-over as a safeguard - and to make sure I can add in binary :)

I'm less familiar with LZ77, but intend to do a similar example in the near future.

Jenesis 16:53, 23 October 2005 (UTC)

 * Shouldn't there be a note saying in what circumstances would the newly-created symbol be sent right away by the encoding algorithm In the ABABA example? Maybe it's obvoius but I'm too dumb to see it ;_) --filu 12:18, 10 November 2005 (UTC)
 * OK, you may disregard my remark. I must had been hit on the head with hammer when I wrote that ;_) --filu 12:30, 11 November 2005 (UTC)

These sentences are difficult to understand:

In the example, so the third triple (0, 0, "c") should be incorporated, what the compression ratio, however, deteriorated significantly.

It is important to note that more and more a character is shifted, was found to be in accordance to new characters do not have to double encode.

I don't know enough to fix this myself. Poelslager (talk) 04:22, 26 June 2015 (UTC)

Equivalence of LZ77 and LZ78
Does anyone have the cite that states that LZ77 and LZ78 are equivalent? I have vague memories that they were very different and that the only similarity is that they were devised by the same people. I also recall reading a paper showing they are equivalent. I can't remember which is correct anymore, but if someone knows of the cite, it would help. Rayjapan 10:46, 15 April 2007 (UTC)

 * I also looked at the page and wanted to put in a "Citation Needed" tag, so instead, I mentioned how LZ78 allows random access to input as long as the entire dictionary is available, while LZ77 does not.--Dwedit (talk) 13:57, 26 March 2009 (UTC)
 * But if LZ78 supports random access given the whole dictionary at any point, then LZ77 supports random access given the whole history buffer at any point. If LZ78 supports random access after the whole item has been decompressed and its dictionary stored in RAM, then this dictionary will likely be at least as big as the union of all history buffers (that is, the whole decompressed stream). Say you have 1024 bytes available for the history buffer or the dictionary; the rest goes to the operating system, and the decompressed stream is going to a character device  without easy random access. At what point is "the whole dictionary" available? If you mean that the dictionary is stored literally in nonvolatile memory (separate from the target archive), that's either metatiling, DTE, or what Witten, Moffat, and Bell in Managing Gigabytes called Huffword, not LZ78. --Damian Yerrick (talk | stalk) 15:01, 27 November 2010 (UTC)

"sliding window"
what's this? —Preceding unsigned comment added by 148.81.137.12 (talk) 16:53, 27 October 2008 (UTC)
 * In LZ77-family algorithms, the "sliding window" or "history buffer" is the end of the uncompressed text before any given point, used as a reference for matches. Please re-read the paragraph beginning "The encoder and decoder must both keep track of some amount of the most recent data" in the article. What about it do you not understand? --Damian Yerrick (talk | stalk) 15:14, 27 November 2010 (UTC)

Patent contravercies
There is a need for a section on patent controversies involving these algorithms. Even though I could find references, I'm not the one to write it, as I have strong opinions on the matter and could not be unbiased.

These patent issues are very important because they were one of the first significant software patent issues on "scope of patent" determined in US courts.

I think such a section should be written from a historical perspective. — Preceding unsigned comment added by RuediiX (talk • contribs) 10:50, 9 January 2011 (UTC)

Ancient history - Stac corporation sued Microsoft for using a particular hash algorithm when recompressing a file in MSDOS 6.20. MSDOS 6.21 removed that feature, and MSDOS 6.22 added it back using a different hash algorithm. Some computer peripheral companies using specific implementations of compression algorithms had to pay royalties for them. Rcgldr (talk) 20:36, 13 May 2011 (UTC)

This article needs some corrections
LZ77 is not a dictionary coder. Instead a history buffer is used and the output codes are length and buffer offset, or a raw data byte. Both the lengths and offsets may be huffman coded. The article has a reasonble explanation of the algorithm.

LZ78 is a dictionary coder, but does not work on future data. Instead the history for LZ78 is it's dictionary instead of a history (sliding window) buffer.

LZW encoder (based on LZ78) - The algorithm starts by setting the next code to 100 hex, and reading the first byte of the input stream and setting current code equal to that first byte. Then each next byte is read from the input stream, and the dictionary is searched for current code + next byte. If a match is found, the current code is updated to equal the index of the matching dictionary entry and there is no output. If a match is not found, a new dictionary code is created at index next code for current code + next byte, next code is incremented, and the currrent code is output. The next byte becomes the new current code. If the dictionary is filled, then no more entries are added to the dictionary. There may be an optional limit for the longest string allowed for a dictionary entry, and if this limit is reached, the current code is forced to be output, but no dictionary entry is added. Compression ratio may be monitored and used to reset the dictionary as needed. A special reset code will be needed to indicate a reset. The size of the dictionary codes in the compressed stream may be also increased with yet another special control code.

LZW decoder (based on LZ78) - The first current code input will be a raw byte, and will be output. last code and last byte will be set to that first code. Then for each current code input, the decoder will index the dictionary in reverse order, retrieving a previously defined code and raw byte with each dictionary entry retrieval. Since it picks up the raw bytes of a string in reverse order, the raw bytes need to be stored in a temporary buffer while the dictionary entries are traced backwards until dictionary code represents a raw byte (less than 100 hex), which is the first byte of the string for current code. last byte is set to that byte and a dictionary entry is created at next code, with values last code + last byte. last code is set to current code. next code is incremented. The buffered string is output. As an option, the decoder could also maintain string lengths in the dictionary and index into an output buffer while retrieving the raw bytes in reverse order. There is one special case where the decoder receives a code that's not yet in it's dictionary at next code. In this case, last code + last byte will be used to create the new dictionary entry, and the algorithm continues normally. If there is a maximum string length, the decoder has to follow the same rules as the encoder.

Note that old pc-dos compression programs such as pkzip include both LZ77 and LZ78 methods, with the main enhancement of using a huffman coding table for the raw bytes based on a scan ahead of the data to be compressed, and dynamic creation of huffman coding tables for the codes to be output. Rcgldr (talk) 15:06, 12 November 2011 (UTC)

 * From the LZ78 section: At this point it will output the location of the word in the dictionary, if one is available, the match length, and the character that caused a match failure. Since the match length is implied by the dictionary word, match length is not output, and only the dictionary word and raw character are output. For LZW, the character that caused the match failure is assumed to be the first character of the next dictionary code, so only the dictionary word is output. For LZW, the final word or character is output when the input stream is exhausted. Rcgldr (talk) 15:06, 12 November 2011 (UTC)

 * updated LZ78 section Rcgldr (talk) 16:34, 12 November 2011 (UTC)

preference of LZ77 versus LZ78 algorithms
The original section for LZ78 mentioned one reason for preference of LZ77 for LZ78 was patent issues, but there has been a history of patents issued for algorithms based on both LZ77 and LZ78.

Regarding preference of LZ77 versus LZ78, one reason is that Intel cpu based programs (at least 16 and 32 bit code) generally compress better with LZ77 based algorithms. For most other file types, compression ratios seem about the same. There are other issues. LZ78 stores strings in reverse order, which the decoder has to deal with. Most LZ78 algorithms add some addtional boundary conditions, such as a maximum string length (if exceeded, it's treated as a mis-match), and monitor compression ratio to see if the dictionary should be reset and a new one built, so they end up more complicated than LZ77 algorithms. Rcgldr (talk) 17:45, 12 November 2011 (UTC)

encoding and decoding section should probably be removed
Someone using the persona Klauria (doesn't exist as a Wiki user) added an encoding and decoding section, along with an example, but it's based on LZW algorighm. It probably should be removed, since it doesn't apply at all to the LZ77 algorithm, and it's an enhancment of the LZ78 algorithm. Rcgldr (talk) 07:47, 22 June 2012 (UTC)

Academic Paper
Is this paper worth including in the article to reference the actual algorithm? — Preceding unsigned comment added by 2602:306:BC90:CE30:213:72FF:FEE6:1A7C (talk) 08:17, 23 December 2014 (UTC)
 * The paper is already referenced in the article. 03:19, 27 December 2014 (UTC)

Quality of text
This article would benefit from a thorough proof-reading as several sections are written in bad English and are, at times, incomprehensible. Ie. LZ77#Example — Preceding unsigned comment added by 86.50.83.184 (talk) 16:48, 8 May 2016 (UTC)
 * Just wanted to say the same thing. Eg. " In the example, so the third triple (0, 0, "c") should be incorporated, what the compression ratio, however, deteriorated significantly. " But I'm not very sure about the topic yet to correct it. Need help. Hoemaco (talk) 20:57, 2 September 2016 (UTC)
 * It's not just you. I have a degree in computer science and had difficulty following the text. 2601:602:9802:99B2:3978:D923:D461:AA4D (talk) 00:45, 22 November 2016 (UTC)

title: Talk:LZ77 and LZ78


text:
Water polo at the 1980 Summer Olympics

Water polo at the 1980 Summer Olympics as usual was a part of the swimming sport, other two parts were swimming and diving. They were not three separate sports, because they all were governed by one federation — FINA. Water Polo discipline consisted of one event: men's team. In the preliminary round 12 teams were divided into three groups. Two best teams from each group (shaded ones) advanced to Group A of the final round to determine places 1 through 6. The rest of teams played in Group B of the final round to determine places 7 through 12.

The event was held between 20 and 29 July in two venues:
 * the Swimming Pool of the Olimpiysky Sports Complex (central part of Moscow)
 * the Outdoor Swimming Pool of the Central Lenin Stadium at Luzhniki (south-western part of Moscow)

title: Water polo at the 1980 Summer Olympics


text:
Arthur Albiston

Arthur Richard Albiston (born 14 July 1957) is a Scottish former football player. Albiston played for Manchester United for most of his career, making almost 500 appearances for the club. He also made 14 international appearances for Scotland and was selected for their 1986 FIFA World Cup squad.

Career
Albiston joined Manchester United as an apprentice in July 1972, turning professional in July 1974. He made his debut in a League Cup Third Round match against local rivals Manchester City in 1974. He made 485 appearances in 14 years, playing at left back, and scored six goals. He helped the club win the FA Cup in 1977, 1983 and 1985.

Albiston left Manchester United in August 1988 for West Bromwich Albion, managed by ex-Red Devils boss Ron Atkinson, on a free transfer. By the time of his departure from Old Trafford he was the longest-serving player at the squad and the only player remaining from the Tommy Docherty era.

He made his Albion debut in a league match away at Leicester City early in the 1988–89 season, and went on to make 47 appearances and score two goals that season, after which he returned to his homeland to sign for Dundee, and went on to play for Chesterfield, Chester City, Molde in Norway and Ayr United. He retired from senior football in 1994.

In his professional career, he made 464 appearances and scored seven goals. He also later joined non-League sides Sittingbourne, Witton Albion and Droylsden.

Albiston also earned 14 caps for Scotland, making his debut on 28 April 1982 against Northern Ireland. His total includes one game at the 1986 FIFA World Cup, a 0–0 draw against Uruguay on 13 June 1986.

Following his retirement from playing, Albiston managed Droylsden (1996–97), was a junior coach at Manchester United (2000–04) and has also worked as a radio summariser for Manchester Independent. He currently works for MUTV, Manchester United's official television channel, acting as match summariser during live coverage of the club's reserve and academy teams.

As a player
Manchester United
 * Football League Second Division: 1974–75
 * FA Cup: 1976–77, 1982–83, 1984–85
 * FA Charity Shield: 1977 (shared), 1983

title: Arthur Albiston


text:
Kurt Haertel

Kurt Haertel (26 September 1910, Berlin – 30 March 2000, Seefeld am Ammersee ) was a German patent lawyer. He played a leading role in the establishment of the European patent system. He is sometimes referred to as one of the "fathers of the European patent law", or the "father of European patent law". He was President of the Deutsches Patent- und Markenamt (German Patent and Trade Mark Office) from 1963 to 1975. In October 1977, he was elected Honorary Chairman of the Administrative Council of the European Patent Organisation.

Since 2003, a street in Munich, Germany, is named after him, the "Kurt-Haertel-Passage". This is the connecting path from the Grasserstraße to the Bayerstraße near the buildings of the European Patent Office.

Publications

 * Die Rückgliederung des Saarlandes auf dem Gebiet des gewerblichen Rechtsschutzes, des Wettbewerbsrechts und des Urheberrechts, GRUR 1957, 98 (with Albrecht Krieger)
 * The New European Patent System, Its Present Situation and Significance, (Dec. 1978) I.I.C., Vol. 19, No.6

title: Kurt Haertel


text:
Gramavision Records

Gramavision Records is an American record label founded in 1979. Since 1994 it has been a subsidiary of Rykodisc. The label's music is largely jazz, blues and folk oriented but has touched on many other styles and genres.

In 1979, Jonathan F.P. Rose founded Gramavision in Katonah, New York. The early catalog consisted of free jazz by Ray Anderson, John Carter, Anthony Davis, and Bobby Previte; jazz fusion by John Scofield; funk by Medeski Martin & Wood; reggae by Oliver Lake; and soul by Jamaaladeen Tacuma.

After it was bought by Rykodisc, the label's headquarters moved to Salem, Massachusetts. in 1995, Gramavision released albums by Peter Apfelbaum, Bill Frisell, Ron Miles, and the Clusone Trio.

Roster

 * Ray Anderson
 * Peter Apfelbaum
 * Arditti Quartet
 * Gordon Beck
 * John Blake Jr.
 * Vinicius Cantuária
 * John Carter
 * Philip Catherine
 * Clusone Trio
 * Anthony Davis
 * Electronic Art Ensemble
 * Pee Wee Ellis
 * Christian Escoudé
 * Aydin Esen
 * Bill Frisell
 * Paul Halley
 * Steven Halpern
 * Billy Hart
 * Motohiko Hino
 * Jay Hoggard
 * Allan Holdsworth
 * The J.B.'s
 * Kitaro
 * Kronos Quartet
 * Oliver Lake
 * Pete Levin
 * Arto Lindsay
 * Didier Lockwood
 * Al MacDowell
 * Taj Mahal
 * Harry Manfredini
 * John Medeski
 * Medeski Martin & Wood
 * Myra Melford
 * Ron Miles
 * Tom Mkhize
 * Bob Moses
 * James Newton
 * Jimmy Payne
 * Bobby Previte
 * Cornell Rochester
 * John Scofield
 * Klaus Schulze
 * Ralph Simon
 * Harvie Swartz
 * Oranj Symphonette
 * Jamaaladeen Tacuma
 * Bob Telson
 * Kazumi Watanabe
 * Bernie Worrell
 * Robert Wyatt
 * Yas-Kaz
 * La Monte Young

title: Gramavision Records