# Wikipedia talk:WikiProject Mathematics/Archive 54

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## A nitpicking style issue

Even today there are poor benighted souls who don't know Wikipedia math notation style conventions.

I sometimes find things like xn, with the subscript not italicized. Here's a guess: some people see things like x1, where the subscript should not be italicized, and leap to the conclusion that that applies to subscripts generally, rather than being about the difference between literal variables and digits.

At any rate, I've always assumed the idea is that non-TeX notation should match TeX style as closely as possible. Michael Hardy (talk) 22:27, 3 October 2009 (UTC)

I assume you are referring to the recent edits you made at Cyclotomic character. I wrote that article and can explain to you that my decision was not a matter of poor pattern recognition, but rather a compromise at the sometimes poor look of html. Italicized super- and subscripts can redner poorly. As an example, consider the following with italicized superscript: Hn. Because html makes no attempt at looking good, the superscript and the base letter overlap, and can be unreadable at times. Now I have since seen the hack H n, and I use that now, but I didn't go back over all previous edits I made to change them all. Especially since html rendering of math is not actually a guideline, and some people go around changing things to TeX anyway. I will assume you weren't calling me "benighted". Though a quick look at the history of the article would have clearly indicated that I was essentially the only editor. Perhaps this whole comment could've been posted on my talk page. Maybe I'm the only culprit. RobHar (talk) 00:22, 4 October 2009 (UTC)
I'm puzzled: You're saying the problems you refer to here explain your decision not to italicize the subscript n? Michael Hardy (talk) 10:18, 4 October 2009 (UTC)
I find that html does a poor job of rendering italicized small fonts in general. The superscript example I described above is a particularly egregious example, but even Hf doesn't look great because the f is so small. So, for a while, I simply decided to avoid italicizing sub- and superscripts for aesthetic purposes. I view TeX emulation not as a goal unto itself, but rather a good approximation to proper aesthetics. Are you still puzzled? Something that puzzles me that you could perhaps explain is why every single time you add a section to this talk page you do so manually and without changing the edit summary so that it appears you are adding to the previous discussion, but really you're not. Now that's puzzling! RobHar (talk) 15:18, 4 October 2009 (UTC)
It's not actually every time, and when it happens it's just haste. Certainly the way we handle both TeX and non-TeX notation has been deficient in some identified ways that we've been talking about at least since the beginning of 2003. How do Hƒ and H ƒ appear on your browser? Michael Hardy (talk) 19:12, 4 October 2009 (UTC)
On my system at least, the kerning on Hn is just as bad as RobHar says it is. It will depend very heavily on the fonts that are used to display the math. TeX itself has to go to great lengths to get the kerning right for mathematical formulas, which is why there are very few mathematics fonts for TeX.
On the other hand, I would just write Hn in an article. I don't think we should worry about things such as kerning for HTML display. But if you do want to add a space, make it a thin nonbreaking space (typed as " "). This gives: Hn. The version with   gives: H n which is too wide for me and probably for everyone else too. See Unicode spaces. — Carl (CBM · talk) 13:37, 4 October 2009 (UTC)
Thanks CBM, that looks much better. RobHar (talk) 15:11, 4 October 2009 (UTC)
He might have noticed it last there but you're hardly the only person to do this sometimes! Dmcq (talk) 08:37, 4 October 2009 (UTC)

Since we are nitpicking, this is a good time for me to ask this question: In TeX, I always write the time complexity of a linear time algorithm as ${\displaystyle O(n)}$. This is the same as in the Big O notation article, and CS papers in general. However, I've noticed that while using HTML, most people just write O(n). (The difference is that the "O" is not italicized.) What is the correct way? Is the big O italicized? (Same question for Omega, Theta, etc.) --Robin (talk) 19:45, 4 October 2009 (UTC)

For big-Oh notation, we should probably follow the pattern used by the majority of CS publications, if there is a pattern. That will minimize reader confusion with our articles.
Greek is a different issue. TeX sets lowercase mathematical Greek in italic by default, but some people use upright lowercase Greek with TeX (in other fonts), and so it is not clear which way is better. Also, certain things are set in non-italic by convention (for example, capital Greek letters are set upright in TeX by default). Personally, when I use HTML entities to type Greek letters in math articles on Wikipedia, I never italicize them. — Carl (CBM · talk) 00:34, 5 October 2009 (UTC)

## D. Rees?

Can someone address the issues I raise at Talk:Don Rees? Michael Hardy (talk) 01:57, 5 October 2009 (UTC)

## List of X topics vs Outline of X

Should articles called List of topology topics etc be changed to Outline of topology etc. User The Transhumanist is changing them all. A particularly ridiculous example is when List of triangle topics was changed to Outline of triangles. Charvest (talk) 13:02, 5 October 2009 (UTC)

...and similarly, outline of circles. Michael Hardy (talk) 13:38, 5 October 2009 (UTC)
There is some background and explanation at User talk:The Transhumanist, accompanied by a growing list of complaints. Some of these page moves are being reverted piecemeal by various editors. Gandalf61 (talk) 13:12, 5 October 2009 (UTC)

There's a WikiProject devoted to this: Wikipedia:WPOOK. Michael Hardy (talk) 13:23, 5 October 2009 (UTC)

If you take a look at The Transhumanist's last few contributions, he talks about accelerating this process and is enlisting others to help. I suggest that you visit the project and warn them to stop and approach this in a very different manner. Such mass changes should be approved on each talk page first. Barring that, a Wiki-wide official policy needs to justify it. Such a style policy/guideline doesn't exist, AFAIK. This needs speedy action to prevent more damage. -- Brangifer (talk) 13:53, 5 October 2009 (UTC)
The Transhumanist has a long history of blatantly ignoring complaints and pushing ahead his pet project of "WPOOK" in spite of everybody else. Apparently, "outlines" need to be forced down the community's collective throat for its own good.
the bottom-line is that we have here an editor who has repeatedly shown his utter contempt for all wikilike procedure of discussion, consensus-building and compromise. I know of no effective way of dealing with such cases other than the warn-block cycle. --dab (𒁳) 14:04, 5 October 2009 (UTC)
Dbachmann is being misleading here. His position in the past has been anti-topics-lists (which includes outlines and "Lists of x topics"). He also fails to point out that I have engaged in a great number of discussions on this subject, have been open to any and all feedback, and have helped to nurture the project to its present state of development through diplomacy, drafting proposed guidelines, and forthright collaboration. The outlines have improved greatly since their conception by the input of many excellent editors. I honestly believed no one would mind the page moves, since we (WP:WPOOK) have been converting topics lists to outlines continuously for nearly a year (one by one via WP:BRD). Dbachmann himself has stated on more than one occasion that he doesn't mind there being an OOK as long as it is moved to another namespace. —Preceding unsigned comment added by The Transhumanist (talkcontribs) 21:01, 5 October 2009 (UTC)

Dbachman, this has been discussed with you before, I need not tell you to see WP:OUTLINE Highfields (talk, contribs) 15:05, 5 October 2009 (UTC)

A proposed guideline is hardly a good reason for undiscussed execution of blatantly wrong page moves such as those mentioned above (Outline of triangles, outline of circles). Outlines are controversial. Renaming lists to "outlines" is predictably controversial. We have two processes for controversial moves: Proposing them on the article talk page, and WP:Requested moves. Which of them was followed in these cases? Hans Adler 15:52, 5 October 2009 (UTC)
The puns aside, those titles share the same grammatical structure as Outline of sharks, Outline of ants, etc. and are grammatically correct. That an "outline of a triangle" is a triangle is irrelevant, as a reader will quickly discern the purpose of the page once the lead is rewritten. The Transhumanist 21:02, 5 October 2009 (UTC)
Answer the question. Which of the processes for controversial pagemoves did you follow? You cannot, by this point, be unaware that there is widespread opposition to your pet project in general, and pagemoves in particular. → ROUX  21:07, 5 October 2009 (UTC)

I don't think the name is very important. Yes, User:The Transhumanist should not be doing these sorts of massive page moves, and someone has already given him or her a warning to stop. But I don't think it's worth wasting too much time discussing the matter, when we could be achieving more useful things than discussing whether "Outline" or "List" is a better word for the title. — Carl (CBM · talk) 15:26, 5 October 2009 (UTC)

I agree. I renamed the articles with the intention to refine them into better (topical) outlines. But if you prefer, we could just wait until new outlines on these subjects are created from scratch. Though I feel the WP:OOK would be a nice new home for these pages, as they would be cleaned up, expanded, and refined in short order. The Transhumanist 21:01, 5 October 2009 (UTC)
I agree that it might be a silly thing to waste time over, but some things are downright ridiculous. What do we do when someone suddenly feels like calling all the "History of X" articles "Glorious and wondrous past of X"? Some of the math articles here are really lists and not outlines. They're just a collection of topics that we happen to have articles on. Those lists don't aim to provide full coverage of the topic or give a high-level outline of the topic. --Robin (talk) 16:31, 5 October 2009 (UTC)
Sorry, I forgot to put "under construction" tags on them. The Transhumanist 20:39, 5 October 2009 (UTC)

Oh God, is he still at this nonsense? Someone block him and be done with it. → ROUX  16:11, 5 October 2009 (UTC)

Can't quite see why outlines should always be called 'Outline of'. Often an article is best written as an outline and this would stop it just being given the straightforward name. It is as if all the disambiguation pages suddenly had to be called something like 'Disambiguation of' even when there's no real main meaning. Yes it would save some messing around for editors but it would hinder users. Dmcq (talk) 10:49, 6 October 2009 (UTC)
• I strongly oppose such a wholesale namechage. The examples given above are just silly, and article names should be unambiguous - links shouldn't surprise the reader. When clicking on "outline of ..." that could be a number of things, but list or glossary etc are pretty clear. (For silly examples, see country articles like Outline of Iraq - I honestly expected a discussion of its borders and things like it's fractal index, etc). I've proposed that the "proposed policy" WP:OUTLINE be marked as failed. 15:12, 6 October 2009 (UTC)
I agree with Verbal. What's the reason behind the name change? I understand the aim of the WP:OOK project, and what you'll are trying to do, but why must all the articles be named as "Outline of X". Why don't you just put your "WikiProject Outline of knowledge" template on the talk page of lists which seem to fall under your WikiProject? --Robin (talk) 15:17, 6 October 2009 (UTC)
If outline of subject is δ subject then the top level outline of the outlines should follow δδ knowledge = {}. ;-) No I think an outline structuring is a good idea, just not the idea of special article names. Dmcq (talk) 16:19, 6 October 2009 (UTC)
Agreed. Outlines aren't bad, but naming everything "outline" can and does result in ridiculous situations. Titles should be unambiguous and unaffected by some sort of OCD-like relationship toward always using particular words in the title. -- Brangifer (talk) 23:57, 6 October 2009 (UTC)

## Kurt Gödel

I have encountered a strange situation at the Kurt Gödel article with someone removing content. I don't think anyone else needs to do anything at the moment, but having that page on more watchlists would help. — Carl (CBM · talk) 19:32, 6 October 2009 (UTC)

## ????? Landau

Landau's constants, named after ??????? Landau, are......

etc. My guess is Edmund. Can someone who knows the answer edit the article accordingly? Michael Hardy (talk) 19:19, 7 October 2009 (UTC)

## Landau's denesting algorithm

We have no article titled Landau's algorithm. I've added some red links to that article from nested radical and from Susan Landau. If anyone knows anything about it, could they write something? Michael Hardy (talk) 20:20, 7 October 2009 (UTC)

...OK, now I've created the article, but it says nothing specific about the algorithm. Michael Hardy (talk) 20:30, 7 October 2009 (UTC)

## Somos sequences

In connection with the deletion nomination for the article on Michael Somos, I started a new article Somos sequence. It's very bare bones right now, just including the basic definitions and a few references, and it's missing a lot of material e.g. on the connections between these sequences and theta-series of elliptic curves. If anyone else wants to take some time to improve it, I'd appreciate it. —David Eppstein (talk) 23:31, 7 October 2009 (UTC)

## Robin Thomas

There are currently eight links from articles to Robin Thomas (mathematician), so if somebody knows something, could they put something there? Michael Hardy (talk) 04:48, 9 October 2009 (UTC)

## Ascending power numbers on AFD

This section was previously titled: "an article which seems to be maintained by a narcissist who writes for his/her fellow mathematicians"

There's an interesting rationale at Wikipedia:Articles for deletion/Ascending power numbers. Uncle G (talk) 07:32, 9 October 2009 (UTC)

## "Michael Somos" nominated for deletion

Comment at Wikipedia:Articles for deletion/Michael Somos. Do not simply say Keep or Delete (or Merge into... or whatever); rather, give your arguments. Currently Somos sequence and Somos' quadratic recurrence constant are mentioned at Michael Somos. Are those enough for "notability"? Are there other things that should be mentioned? Michael Hardy (talk) 19:18, 9 October 2009 (UTC)

Somos' quadratic recurrence constant expresses the constant as the derivative of another constant, a particular value of a three-parameter function. Presumably this should be some derivative of the function itself; can someone fix this? Septentrionalis PMAnderson 01:31, 10 October 2009 (UTC)

## Cyclic permutation of integer nominated for deletion

If interested, please comment at Wikipedia:Articles for deletion/Cyclic permutation of integer. Note that just saying delete or keep is not constructive — reasons need to be given. — Arthur Rubin (talk) 00:52, 10 October 2009 (UTC)

## Division by two

I just came across the article Division by two, which is unfortunately completely unsourced, and has been so since its creation in 2002. First I thought that this is just an unnotable simple special case, but then it occurred to me that there might be some historical interest in this algorithm (cf. Peasant multiplication which incidentally requires a division-by-two algorithm); does anyone know any sources or background? — Miym (talk) 17:51, 10 October 2009 (UTC)

I added some sources. —David Eppstein (talk) 02:56, 11 October 2009 (UTC)
Looks a lot better but the heart of the article, the algorithm to divide by 2 base 10, is still unreferenced. Factually it looks ok, and most people learned it grade school, so maybe it doesn't need a reference. But I'm not sure it's encyclopedic and WP:NOTHOWTO seems to imply that it isn't. Maybe that section should be moved to WikiBooks.--RDBury (talk) 14:52, 11 October 2009 (UTC)
There's a similar (though not identical) algorithm in the 15th-century algorism citation. And it would be stupid to use WP:NOTHOWTO to imply that descriptions of algorithms are forbidden. —David Eppstein (talk) 16:14, 11 October 2009 (UTC)

## Clarity

Now we have

Two quite different things.

Great.

All perfectly clear to the newbie or casual reader.

Right?

Michael Hardy (talk) 06:11, 11 October 2009 (UTC)

One is a list and one is a list of lists. It seems to me that the list of lists (whichever it is) should be changed to a category, e.g. [[Category:Lists of mathematical articles]].--RDBury (talk) 14:30, 11 October 2009 (UTC)
Actually, that category already exists Category:Mathematics-related lists, maybe a merge is in order?--RDBury (talk) 14:33, 11 October 2009 (UTC)
Maybe one of them should be called an "Outline." --Robin (talk) 14:41, 11 October 2009 (UTC)

Interesting.

I would suggest just redirecting List of topics in mathematics to Lists of mathematics topics, and focusing on making the latter as useful as possible. — Carl (CBM · talk) 18:12, 11 October 2009 (UTC)

I'm inclined to agree. Michael Hardy (talk) 21:41, 11 October 2009 (UTC)

The proposal to change lists of mathematics topics to a category is lunacy! This was once a "featured" list, representing Wikipedia's best work. It lost that status only because of a lack of references. Categories are vastly inferior to lists. This list is a good example of HOW categories are inferior to lists. Doesn't Wikipedia have a policy that these two formats are complementary—that one should not eschew one of them because the other exists? Michael Hardy (talk) 21:40, 11 October 2009 (UTC)

Yes, they complement each other and there is a page about it: Wikipedia:Categories, lists, and navigation templates. I agree that Lists of mathematics topics should not be replaced by a category, which would be much worse for browsing. But I think that, within the list of lists, we should not list categories as well. If the lists are set up right, each category that we link to there has a corresponding list that we can link to instead. — Carl (CBM · talk) 22:17, 11 October 2009 (UTC)

## Earliest uses of mathematical terms

This is a useful source of external links. But when an anonymous user adds a good link to one of its pages to an article, User:XLinkBot automatically deletes it without any human supervision. If the user also adds content to the article, all such content is deleted along with the link. I think this WikiProject should endorse this particular site. Michael Hardy (talk) 21:51, 11 October 2009 (UTC)

I also find that site useful; I have used it to explain things to my classes. I think that people should feel free to use it in articles. But if it is a reference, the opinions in it should be cited to Miller. So rather than "The first use of 'field' for the algebraic structure was by E.H. Moore in 1893", say "According to Miller (CITE), the first use of 'field' for the algebraic structure was by E.H. Moore in 1893." Questions about priority of results and terminology are notoriously prone to disagreement.
As for XLinkBot, it claims that it allows established users to add links, only reverting new users and IP editors. — Carl (CBM · talk) 22:22, 11 October 2009 (UTC)
Can some domains be white listed? It would make sense to do that. Le Docteur (talk) 00:24, 12 October 2009 (UTC)
I tried something, it didn't work. I will see if it can be done. — Carl (CBM · talk) 02:38, 12 October 2009 (UTC)

## Revised Near sets article

Hi all, I have updated the article Near sets based on some feedback I received from this page a few months back. I invite any who are interested to check out the updated article to offer some suggestions to help improve it further. Thanks in advance. NearSetAccount (talk) 15:37, 13 October 2009 (UTC)

Not my cup of tea but it's been nicely laid out. I can think of a lot of articles that could do with a makeover like that. Dmcq (talk) 16:31, 13 October 2009 (UTC)

## Gyrovectors

I am not sure if this is the right place to ask but could somebody have a look at the Gyrovector space article. Martin Hogbin (talk) 22:26, 13 October 2009 (UTC)

I haven't really examined the article to determine if it is obvious woo or not, but there are only 7 mathscinet links with gyrovector in the title, all of which were published by a single author, although some of these were actually reviewed. It is not cut and dry, but this does seem to be a case in which an encyclopedia article is probably premature. Le Docteur (talk) 00:15, 14 October 2009 (UTC)
These Google books and Google Scholar results show that there are far more than 7 papers or one author.
Some of those results aren't relevant, but most of them are.
Charvest (talk) 03:37, 14 October 2009 (UTC)

Article needs a fair amount of chat removed. There is a nonassociative structure in there to document. Articles in the area of linear algebra in mathematical physics do tend to lead off with claims that this is an entirely new way to look at things; that is almost always going to be POV, and such claims are not what make a topic notable. Charles Matthews (talk) 07:30, 14 October 2009 (UTC)

A bit off-topic -- but -- virtually all of the edits I do at WP are on math articles, with some spill-over to physics and comp-sci. I've not been active for the last few years, because I got tired of the editorial nonsense that goes on. Despite being inactive, I recently was attacked, more or less unprovoked, by a new-age editor who had vandalized an obscure math article I wrote, and someone else reverted. When I told him off, I was promptly piled-on by five admins who blocked me for several weeks. I'm kind of shocked that the power structure here has changed so much that we've got these kinds of nasty, abusive people in admin roles. I complained to the Arb, but they ignored the case. I don't know what to do, other than to complain here, and ask everyone to try to band together, and to figure out how to get the ugly admins and the (incompetent?) leadership out of power, redo Wikipedia leadership, and restore some sanity. linas (talk) 16:42, 13 October 2009 (UTC)

The following is apparently what happened. In the article titled history monoid, this work was cited:
• G. Rozenberg and A. Salomaa, editors, Handbook of Formal Languages, Vol. 3, Beyond Words, pages 457–534. Springer-Verlag, Berlin, 1997
User:Aboutmovies mistakenly thought that "Beyond Words" was the publisher rather than part of the title, and changed it to [[Beyond Words Publishing|Beyond Words]], so that the reader saw this like: Beyond Words. Someone changed it back with an explanation in the edit summary that that's part of the title, not the name of the publisher. The publisher is Springer-Verlag. Michael Hardy (talk) 18:35, 13 October 2009 (UTC)
The contribution of Linas is quite impressive (I have visited several pages on different topics). However, his message above contains no links, and so, I do not understand what is really the problem. Boris Tsirelson (talk) 19:18, 13 October 2009 (UTC)
There is an ANI discussion here with opinions by various people and additional pointers. Hans Adler 19:21, 13 October 2009 (UTC)

This has been forum-shopped to Mediation, to the Arbitration Committee, and now to the talk pages of several WikiProjects. Editors coming to this situation with no prior knowledge should read Wikipedia:Administrators' noticeboard/IncidentArchive564#Nuclear meltdown at User talk:Linas, Wikipedia:Administrators' noticeboard/IncidentArchive567#User:Linas again, Wikipedia:Requests for mediation/User:Linas, and this declined ArbCom request to get up to speed. Please place all further discussion at Wikipedia:Administrators' noticeboard/Incidents#Linas, soapboxing on wikiprojects (and userpage), rather than having lots of little disjoint discussions everywhere that this has been shopped around to. Uncle G (talk) 02:05, 14 October 2009 (UTC)

Comments. Linas, you have been a good if quirky contributor to the project. Not so much has changed, but there is a definite effort on foot to improve standards of civility around the site. Just as in the past we have discussed mathematics and you have accepted that you have made technical mistakes, I think you should accept that you have made a mistake of escalation over the initial issue, which need not have been a big deal. If you need an advocate for your past efforts, I'll speak to whoever needs to hear about that. But when I have seen others attack the "system" in this way, I have always felt they were misunderstanding some of the factors, even if the mistakes were not all on one side. Charles Matthews (talk) 08:09, 14 October 2009 (UTC)
Does anyone else get a nagging feeling that there are two (or more) people running the User:Linas account? It is difficult to reconcile the impressive list of contributions with the spoiled teenager that calls people "fuck brained idiots". Is that the normal Jekyll and Hydeism from this account? Or is a checkuser perhaps in order? 10:55, 14 October 2009 (UTC)
Calling Linas a "spoiled teenager" is not really helpful. Linas, though prickly at times, has made major contributions to our project, and while he has not handled this situation very well, it would be good for others to examine their behavior as well. Paul August 13:09, 14 October 2009 (UTC)
My point was that it seemed like a spoiled teenager personality. I've never known anyone over the age of 17 to use such terms. If it turned this was a mathematics post-grad sharing an account with an angry 15-year-old brother, I would not be surprised in the least (and it wouldn't be the first time I encountered such a situation). 13:31, 14 October 2009 (UTC)
I understand the point you are trying to make. Nevertheless I don't think the way you are trying to make it is helpful. Try to consider how you would feel If someone said your behavior seemed like that of a "spoiled teenager". Paul August 13:54, 14 October 2009 (UTC)
I would feel like maybe I am coming across quite immaturely and I should probably smarten up (as we Maine folks say). But if you think I'm an anomaly in that regard, that's fine, I'll drop it. 14:11, 14 October 2009 (UTC)
Thanks. Paul August 17:55, 14 October 2009 (UTC)
I don't think so. From the contribs, it seems like Linas has a good understanding of advanced math topics. Consequently, people who don't understand advanced math appear stupid to Linas, and by extension, they appear to be "fuck brained idiots." --Robin (talk) 11:54, 14 October 2009 (UTC)
I am not seeing anything that can't be explained with misunderstandings. If I had been in Linas' situation and had believed that Aboutmovies was a sneaky vandal, I might not have behaved too differently. Hans Adler 12:11, 14 October 2009 (UTC)
I knew two people, incidentally, one being a University Math Professor, who could go berserk at any manifestation of stupidity however minor. And do not forget we do not know anything about linas' personal life, the trigger might have been outside Wikipedia. (Igny (talk) 12:45, 14 October 2009 (UTC))

Charles and others, it would seem to me that on this point, the goals of increasing civility on Wikipedia and actually building a good encyclopedia are somewhat in conflict. Wikipedia is not so rich that it can afford to run off everybody who's capable of being provoked, no matter how great their energy or extensive their contributions. Frankly, the whole incident looks like it could've been avoided if people had been allowed, you know, to blow off steam. Standards of admin action developed amidst our most ferocious disputes and hardened by arbcom remedies on bitter cases of protracted conflict do not need to be applied injudiciously across the rest of Wikipedia. RayTalk 15:30, 14 October 2009 (UTC)

No, the goals of increasing civility and, for example, increasing our participation of women are entirely in line with each other. As for any other group, such as older folk, who find displays of petulance and profanity to be a discouragement. I think you'll find that I was suggesting a way ahead, rather than arguing that the business was handled the best way. Charles Matthews (talk) 16:32, 14 October 2009 (UTC)
(edit conflict) @Ray: At the risk of getting into a general civility discussion, your argument cuts both ways. Wikipedia is not so rich that it can afford to have calm civil productive editors run off by people who overreact and blow innocent mistakes completely out of proportion. People won't accept that type of incivility when they're being paid, much less when they are volunteering. 17:27, 14 October 2009 (UTC)
Wknight, you are correct. This is why this is a situation where I felt a touch of forbearance and discretion, rather than a rules change, would've been a good idea. It was a situation where an editor was blowing off steam on somebody else's talk page, and the person to whom he was blowing off steam was not the one being insulted. That was not a situation threatening to escalate absent outside intervention, and in hindsight it clearly was a situation where outside administrator intervention was likely to aggravate things, and I believe it did not require hindsight to forsee it as such. Charles, sorry for misunderstanding your comments above. RayTalk 19:35, 14 October 2009 (UTC)

People! Please! This has nothing to do with mathematics articles. Please take it to the WP:AN/I section linked-to above. Uncle G (talk) 23:56, 14 October 2009 (UTC)

• No, I think a discussion here has been fruitful, and has reached some people unaware of the civility issue, in the terms in which it is now posed. And I for one am not that impressed with AN/I as a forum for actually resolving disputes, rather than propelling rather reactive admins in the direction of trouble. It has no charter, you know; it is not appointed in any way, and is simple a "noticeboard", i.e. a sort of process that is unregulated. Which is part of the problem here, possibly. In any case it has no particular jurisdiction and there is no need to make claims for its centralising function that cannot be upheld. Charles Matthews (talk) 09:45, 15 October 2009 (UTC)
• None of which is relevant, and framing this as some sort of bizarre antipathy to WP:AN/I is ludicrous (especially given that the "centralizing function" in this case not only can be upheld, but is downright obvious). This discussion has nothing to do with mathematics articles, isn't a dispute resolution, and is a ForestFire that has been deliberately ignited in multiple places by Linas. Note that the people at Wikipedia talk:WikiProject Physics have seen the sense of having this discussion in one place, and that their WikiProject is not the proper forum for it. They at least would like the attempts to stir up drama irrelevant to their project off their project, so that they can stick to what they actually set up the project for. ☺ Uncle G (talk) 11:23, 15 October 2009 (UTC)

With all due respect, the members of the project can discuss what they like here; and the status of a long-term, valued contributor to the project is hardly off-topic. It is relevant to getting articles written in a specialist area, where there is a shortage of specialists, if that has to be spelled out for anybody. I've made it clear above that I have interacted in the past with Linas. So that would be enough heckling, really. Charles Matthews (talk) 11:33, 15 October 2009 (UTC)

Agree with Charles Matthews. Here we can have an informed, civilised and on-topic discussion. At ANI that is .. well ... less likely. Gandalf61 (talk) 11:39, 15 October 2009 (UTC)
Yes, Charles has it right, this conversation is certainly relevant to this project. Paul August 14:57, 15 October 2009 (UTC)
Indeed, a point that I made on linas' talk page is that it would be better to decentralize this sort of thing by strengthening the role of Wikiprojects in dispute resolution. This can probably help to mitigate some of the drama that ordinarily goes with WP:ANI. Le Docteur (talk) 01:44, 16 October 2009 (UTC)
The difficulty, as with all aspects of life, is finding people who are interested. At least people who follow ANI are trying to follow the drama; people who follow wikiproject talk pages may not be interested in dispute resolution. More to the point, they may feel that they just don't want to get involved in in the interpersonal disputes of the other editors in their project. I know that I often feel that way. — Carl (CBM · talk) 02:02, 16 October 2009 (UTC)
This is too bad, Carl. As good citizens, we should certainly take interest in the places where we live and work and strive to maintain their integrity. It is all too easy to write off disputes and even abusive behavior as "drama" and "interpersonal relations" and to say "count me out". Worse, there is a sliver of editors, including some even here, on the math project, who take advantage of the apathy you've described and engage in egregious violations of even the most basic wikipedia policies with complete immunity. Leaving it to ANI or to drama-obsessed crowds has not worked in the past and will not work in the future. You, no doubt, know several instances of highly valued and productive contributors to the project who have stopped participating for this very reason. I, for one, became very disillusioned with the lack of commitment on the part of the math community on wikipedia to maintaining supportive atmosphere conductive to creating a quality math encyclopaedia. Arcfrk (talk) 16:11, 16 October 2009 (UTC)

## gratuitous application of l'Hôpital's rule

I'd be grateful if someone could comment on talk:sinc function. — Emil J. 16:22, 16 October 2009 (UTC)

## Preposed removal of /Comments pages

Mathematical article assessments on article talk pages (the {{maths rating}} templates at the top of mathematical article talk pages) are often backed up by comments. These comments provide, at the very least, a signed date for the assessment (which has in the past been regarded as an essential part of our assessments); ideally they also provide basic suggestions for improvement. This project has found such pages useful.

A recent Village pump discussion suggests that editors elsewhere may not be fully aware of the value of /Comments pages to WikiProjects. A greater awareness may result in a better conclusion. Geometry guy 23:08, 16 October 2009 (UTC)

## Computability theory, Complexity theory and Formal languages

I'm cross posting this from WikiProject CS since there are many editors here who are interested in these topics. If interested, please take a look at my request on Wikipedia_talk:WikiProject_Computer_science#Can_someone_take_a_look_at_this.3F, and reply there to keep discussions unfragmented. In short, I've translated a German image which shows the relationship between these three fields. It might make a good addition to some of our articles on these topics. Thanks. --Robin (talk) 17:17, 17 October 2009 (UTC)

## Polytope articles

I was looking over the list of geometry stubs and noticed there were over 100 articles on hyperdimensional regular polytopes. From the sample I looked at, most of them are marginal OR and of doubtful notability. For example there is a separate article for each hypercube from dimensions 5-10 but the references cited just give formulas for the n-cube. So someone plugged six different values of n into the formulas and used a lot of copy and paste to generate six articles. I realize that this is to be expected to a certain amount for stubs, but it's hard to imagine that any significant material will be found to expand these articles any further. List of regular polytopes already includes any notable information and they stop being interesting after dimension 5 anyway because they fall into a few simple families. So, anyone second the motion to PROD them or at least replace them with redirects?--RDBury (talk) 04:32, 18 October 2009 (UTC)

The thing is, each of these articles has several nice pictures of the cube in question, as well as a bit of useful information. Your complaint is valid, but the same complaint could be made about the articles for nonagon, decagon, triskaidecagon, tetradecagon, etc., or about the countless articles on individual natural numbers. I don't see how these articles are hurting anybody, and together they have far too much content to be summarily deleted.
From my point of view, a larger problem is the standardized template for all of the polygon and polytope articles. It works quite well for articles such as Elongated triangular gyrobicupola, but it seems absurd to focus on the technical polytope classification in the cube and tetrahedron articles. Is there a particular reason that visitors to square (geometry) are immediately greeted by the Schläfli symbol and the Coxeter–Dynkin diagram? Jim (talk) 07:55, 18 October 2009 (UTC)
There is some difficulty here in applying the idea of "notability" sensibly. There is a substantial research literature on polyhedra; documenting the members of certain lists of polyhedra may not be everyone's idea of fun, but it is close enough to the general idea of being "encyclopedic" in relation to certain aspects of geometry for me to be somewhat uncomfortable with the concept of just doing without the information. At what point in Petrie polygon would the reader best be served by saying "and so on"? Well, the main thing to say that is that it is debatable, not that content policies force us to do so earlier. Charles Matthews (talk) 12:47, 18 October 2009 (UTC)
I can't say I'm entirely convinced by your arguments, but on the principle of "Choose your battles," I won't argue the matter.--RDBury (talk) 14:30, 18 October 2009 (UTC)

## Merge two categories?

Why are Category:Arithmetic and Category:Elementary arithmetic two separate categories?

Greatest common divisor was listed in the latter category but not the former. (I added the former a couple of minutes ago.) How does that make sense? How would one know that something should be in one of those categories and not the other? Michael Hardy (talk) 17:30, 18 October 2009 (UTC)

These categories are clearly not being used in a compatible fashion, but there may be a reason to have two different categories. For example, a subcat of "Arithmetic" is "Formal theories of arithmetic". It could be a good idea to consider the category "Arithmetic" as containing stuff about arithmetic, and the category "elementary arithmetic" as containing stuff that is arithmetic (in the elementary sense, not the "higher sense"). I dunno. RobHar (talk) 21:17, 18 October 2009 (UTC)
I guess my comments possibly justify having two categories for the union of the content of these two categories, but that doesn't justify the names. Perhaps a category called "arithemetic" containing stuff about arithmetic, and call the other one "Arithmetic operations", or something of the sort. RobHar (talk) 21:20, 18 October 2009 (UTC)
I suggest merging Category:Arithmetic into Category:Elementary arithmetic, possibly adding a subcategory called "arithmetic operations". I suspect that "elementary arithmetic" is probably a better name for the final category than "arithmetic", since the latter might accidentally attract non-elementary articles on number theory. Jim (talk) 23:08, 18 October 2009 (UTC)
Category:Computer arithmetic being a subcategory of Category:Arithmetic and not a subcategory of Category:Elementary arithmetic makes perfect sense though: anyone who has ploughed through Knuth's explanations of the details of machine arithmetic can see why that stuff isn't "elementary" in a pedagogic sense. The arrangement of categories I see right now seems reasonable. Charles Matthews (talk) 07:34, 19 October 2009 (UTC)
The current arrangement looks alright. Not all arithmetic is elementary and currently Category:Elementary arithmetic is a subcategory of Category:Arithmetic to reflect that. I think the original confusion is because Greatest common divisor should have been in Category:Arithmetic and not the other one. Probably both categories should be reviewed to ensure all the topics are in appropriate places.--RDBury (talk) 20:42, 19 October 2009 (UTC)
Going through the articles, it occurs to me that the distinction between elementary and not can be a bit tricky. For example Least common denominator is something you might learn for adding fractions in grade school, but Least common multiple which is sort of the same thing, is a bit more advanced, especially if you start talking about the intersection of ideals in a P.I.D.--RDBury (talk) 21:15, 19 October 2009 (UTC)

## Outlines in general and List of logic topics

Despite there being no support outside of the small, disputed, WP:OUTLINE project for the "outline of" naming, and despite agreemnet here against using this naming in maths articles, and an agreement by the prime mover (if you'll pardon the pun) of the outline project not to rename lists to outlines, List of logic topics has recently been renamed to Outline of logic. The move was made after TT asked an admin after a small pile on from outline project members, who clearly do not represent the wider communities views on outlines, at the talk page. This is despite agreeing to form a general community consensus. I oppose this rename for several reasons. Firstly, it is non standard and with many maths articles (such as outline of circles) gives silly names, secondly lists are standard and supported by policy and guidlines, thirdly lists are not forced to follow the WP:OUTLINE layout which is restrictive, goes against WP:MOS, and controlled by a few members of the outline project. Lastly (for now) the article is a list, and would be easier to find and the content less ambiguous if it remained named as a list. I'd like more input on this in general, and this one example in particular. Thanks, 07:21, 19 October 2009 (UTC)

Well, that page is more like an outline of logic, not confined to mathematical logic, than (for example) list of topics in set theory is like an outline of set theory. Your first two arguments are really generic against "outlines"; and I think it better to argue out each case separately. Charles Matthews (talk) 13:03, 19 October 2009 (UTC)
Considering there is no support for outlines at all, that should be established first. Once some consensus for outlines at all exists, then it might be worth individual discussion. By the way, the outline of set theory is here, and not the list you give. Lists are more powerful and can be structured to represent the material in the best possible way. 13:50, 19 October 2009 (UTC)
I like lists; I have created many. I don't think that gives me the right to say that the material in a list cannot ever be dealt with another way, though I have often resisted changes to a category. The discussion on "outlines" obviously ought to go along the lines of pros and cons, as conversion of a list to a category should, and be based on the particular case. I think your position amounts to saying that there are no "pros", only "cons", for an outline. As long as others don't accept that, I think we ought to listen fairly for the statements on the other side of the argument. Charles Matthews (talk) 16:23, 19 October 2009 (UTC)
I guess Verbal has become hardened due to the really obnoxious way that The Transhumanist initially reacted when the conflict first broke out. I may be able to provide pointers, or perhaps someone else can. Hans Adler 16:26, 19 October 2009 (UTC)
Yes, obviously, but to get discussion back onto a rational basis we should ignore the personal side and try to look at what is proposed in the light of improving the content (and nothing else). Charles Matthews (talk) 16:29, 19 October 2009 (UTC)
Well, to begin with, using "Outline" to mean a structured list in a geometric context is bizarre. Even if TT's definition of "outlines" is rational and has a place in Wikipedia (in spite of the fact that he has not provided evidence of consensus for the moves of "List" articles to "Outline" articles), the name needs to be changed with respect to geometric topics. (I'm waiting for the article Outlines of outlines; meaning "outlines (grammatical) of outlines (geometric)".) — Arthur Rubin (talk) 16:35, 19 October 2009 (UTC)
And it does relate to "pros" and "cons"; there seems to be no argument made in favor of the name "outline", except in an obscure location in WP:VP, and in the beginning of TT's WIkiProject (with the arguments having fallen into the archives). I would like to see some arguments in favor; perhaps they have some credibility, after all, in spite of the <redacted; I can't think of a good word to describe it which doesn't violate AGF> methods used to perpetuate the name in list articles. — Arthur Rubin (talk) 16:39, 19 October 2009 (UTC)
OOK looks like a really good idea from its description on Portal:Contents, a "table of contents" for Wikipedia. Unfortunately, the heavy handed methods used by some of the project members seem to be more irritating than helpful. To be fair though, at least one of the articles they created (Outline of water) was turned into a list without _their_ permission so there has been heavy-handedness on both sides. How is it that we've gotten to the point where it's "OOKers" vs "listers" and neither group is going to be happy until the other is wiped from the face of Wikipedia? In any case, these major moves with little discussion (or discussed Arthur Dent house eviction style) only seem to fan the flames and whatever the merits of the new name it should not be done without some kind of consensus building.--RDBury (talk) 20:01, 19 October 2009 (UTC)
For the record, two old discussions on this type of move in VP:1, 2

### The status and potential of outlines

Dear Mathematics WikiProject members,

Please see the discussion at Talk:Outline of logic. I'm very interested in feedback on my presentation of the pros (vs. cons) there. Do they lack substance?

I've stopped moving lists to outlines, except for seeking the reversion of outlines that were recently moved by Verbal over and above his reversion of the move of about 50 articles that I made. The outlines I'm seeking to revert back to outlines have been called outlines for a long time, or were renamed to outlines by others based on work they did on the articles, and the articles either share the format of the set of outline articles or have a strong hierarchical structure in their own right.

Concerning the 50, I figured that moves (including mass moves) that did not receive opposition were OK. I misjudged the response that I'd get to that group move. (Oops).  :) It won't happen again - I'll stick to creating outlines from scratch or proposing a rename on the talk pages of articles that have a strong hierarchical structure.

Verbal's entire argument seems to be that the name "Outline of" is bad, because it doesn't have consensus. I think I've countered this argument pretty well at Talk:Outline of logic, and have asked there that the opposition explain how "List of" is semantically better than the title "Outline of".

I'm confident that the ambiguity problem can be solved for those outlines with titles that are puns. Think about the inevitable "Outline of the Bible", for instance.  :) "Outline of Bible-related topics" is a possible solution, and is grammatically and semantically sound. That format works for geometric shapes too.

One rationale for the recent group move was that I assumed I would be able to develop the weakly-structured pages amongst them into well-structured outlines quickly. But I immediately got bogged down with complaints and warnings over the move, so there was no opportunity (or support) to work on them. And I forgot to place {{construction}} tags on them to indicate that they weren't intended to stay in the current state for long. The result was misnomers, which were strongly criticized. I'm sorry about the confusion.

I agree that consensus should be established for or against the "Outline of" name. In my opinion, since arguing over naming conventions and procedures has produced a standstill for many months, only a proposal to rename outlines to something else (at WP:VPR) will determine with certainty what these pages should be called. Most of these articles have been called "outlines" for over a year now, and blatantly reverting them at this late date would be disruptive (and efforts so far to revert them have proven to be just that).

I also agree that the structuring and standard design of outlines can be improved, but my philosophy here is that if the data is parseable, why manually configure it? Isn't that why we have computers in the first place? Manually altering the format for the whole set of outlines has proven to be ever more time consuming and tedious as it grows in size. So I have shied away from tweaking the format, and I am currently in the process of exploring programming options for providing users with interactive control over how they view and navigate outlines - and through those, Wikipedia as a whole. As long as an outline's hierarchical structure can be discerned (identified and parsed) by the software (whether the software is a script, browser add-on, or new MediaWiki features), a great deal of control can be provided to the user, in how he sees it on the screen and in how he navigates it.

And that's just for starters. This is the tip of the iceberg.

More to come (eventually)...

Sincerely,

The Transhumanist 02:02, 20 October 2009 (UTC)

#### Straw poll and discussion concerning what outlines should be called

The Transhumanist 04:27, 20 October 2009 (UTC)

## Synergetics coordinates

Can someone take a look at Synergetics coordinates? I'm not much sure what they are, but the page gets changed from time to time. They seem to be related or unrelated to Synergetics (Fuller), and/or a Clifford J. Nelson, and the latest edits are by a User:Cjnelson9. Shreevatsa (talk) 04:20, 9 October 2009 (UTC)

It all sounds a bit like Sacred geometry to me, I'm not sure an approach as mathematics would satisfy adherents who came along to read about it. Dmcq (talk) 15:26, 9 October 2009 (UTC)
Is there any reason not to prod the article? This article seems to flout just about every policy: WP:OR, WP:COI, WP:FORK, and so forth. 74.98.46.147 (talk) 22:28, 10 October 2009 (UTC)

Just now saw this discussion. The article was "prodded" on Oct 10, and I "de-prodded" on Oct 15, since I think that the article ought to go through AFD before being deleted. Paul August 20:15, 20 October 2009 (UTC)

## Halting problem and Likebox

In my opinion, he's at it again. I can't find any restrictions he may be under, but he's reformulating the halting problem to remove the input, claiming it's the "modern" approach; and then adding a "modern proof", replacing the diagonalization by quining. I'm at 3RR, but I believe he is, also. Any input as to whether any of his assertions are correct (whether or not "input" is "modern", the proof uses inputs) would be appreciated. — Arthur Rubin (talk) 01:17, 15 October 2009 (UTC)

First, you aren't at 3RR, and neither am I. You are at "1R", and I am at "2R". If you revert some of the material, I'll discuss.
Second, yes, I'm "at it again", because I was annoyed the first time that people would not accept discussions which sound a little different than textbooks. There are some proposed guidelines which I think help: WP:ESCA, and perhaps with these guidelines, consensus can be made to swing the other way.
I have no complaints with your behavior, and I understand and sympathize with your position. I just disagree.Likebox (talk) 01:21, 15 October 2009 (UTC)
While I agree with both your points, the canonical description of the Halting problem is with input. See the most modern book in Complexity theory (Arora and Barak's 2009 text); even that treats the version with input. While I like the quining and no-input version, that shouldn't be the main version in the article. I believe a separate section should highlight the formulation without inputs with the quining proof. --Robin (talk) 01:44, 15 October 2009 (UTC)
But the same book surely states the theorem with no input too somewhere. That's also a standard result. For example, Wolfram mathworld states it without input.
Also from googling:
As an example of his thought let's look at a proof that there is no way of telling in general once a computer has embarked on a calculation whether that calculation will terminate in an answer. This problem is known as the "Halting Problem for Turing machines" and was first proved in the 1937 paper[2] in which he introduced his machines.
Again, no input. I have found cases where people state it with input, and others where it is stated without. Since both are true, both are almost identical, and the input is only there to simplify the proof a tiny bit, I think it is misleading to make the input so prominent in the lead.Likebox (talk) 01:57, 15 October 2009 (UTC)
As I said, I appreciate your point, and I do like the no-input version, but the article's lead section should have the canonical version which everyone is used to reading in their first year CS course. Moreover, I think the diagonalization proof is easier for a new reader. Once the reader has grasped this, the reader can move on to the no-input version and quining proof. --Robin (talk) 02:04, 15 October 2009 (UTC)
Mm. I am far from knowledgeable about computation, but I just took a look at Sipser (which I understand to be something of a standard introductory text in the subject), and he uses finite input strings in his description. I think, if people knowledgeable on the subject are not in agreement to the contrary, we should probably stick to the standard pedagogical approach. It's fairly common for there to be sections towards the end describing generalizations and extensions of the theory, however, so that might be a good place for Likebox to put his stuff? RayTalk 01:38, 15 October 2009 (UTC)
The issue is entirely pedagogical. I agree that textbooks do not often mention quines in this context, but I feel that this is a pedagogical mistake. People knowledgable in the subject don't think about this, because it is too elementary to waste time thinking about. It is in these situations that bad pedagogy can flourish.
But we don't have to be stuck with bad pedagogy. If there is a nice text which explains sourced material well, but doesn't sound exactly like a textbook, that's OK according to WP:ESCA, so long as it is accurate, clear, and explains intermediate steps in well referenced results.
In this case, the theorem is this: You can't write a program HALT which takes P as input and decides if P halts or not.
One way to state the proof is: Write SPITE to print its own code into R, calculate HALT with input R, and if the answer is "R halts" go into an infinite loop, and if the answer is "R doesn't halt" to halt.
This proof is trivial, and the only question is whether a program can be made to write its own code. This is slightly nontrivial, but it is an exercise for computer science freshman.
The other way to prove this is to say "It is undecidable whether program P with input I halts for arbitary P and I". Then you prove it this way. Suppose HALT(P,I) tells you whether P and I halts. Then write SPITE to take input I, and evaluate HALT(I,I), and if the answer is "I halts on input I" SPITE goes into an infinite loop. If the answer is "I does not halt on input I" then SPITE halts.
Then you ask if SPITE is given as input the code for SPITE, what does it do? You see, it's exactly the same proof, except that the code for SPITE is given to SPITE as input, instead of being generated by SPITE at step 1.
I think that the proof where SPITE prints its own code is clearer. To prove that a program can always print its own code is very simple, using the diagonalization argument.Likebox (talk) 01:52, 15 October 2009 (UTC)

I disagree with Likebox's opinion that Wikipedia should promote pedagogical innovations not present in standard textbooks like stating the Halting Problem the way he likes it. Pcap ping 07:41, 17 October 2009 (UTC)

### Also Gödel's incompleteness theorems

The same issue at Gödel's incompleteness theorems, where Likebox has previously added "modern" proof that was removed. It helps to have more eyes on these pages. — Carl (CBM · talk) 02:05, 15 October 2009 (UTC)

This is particularly problematic because Likebox tends to revert the removal of his proofs. — Carl (CBM · talk) 02:10, 15 October 2009 (UTC)
I don't like it when people delete 8K of material written over several hours without discussion. It's impolite to the effort I put into the new text. I know you have issues with this stuff, but mull it over. These proofs are sorely needed. I have had discussions about this with five or six mathematics students over the past week, and their encouragement is the only reason I came back to these pages. The current proofs of Godel's theorem is illegible, and it is beyond the grasp of most undergraduates. That needs to change, and WP:ESCA is a good way to allow it to change.Likebox (talk) 02:13, 15 October 2009 (UTC)
The issue was discussed, in depth, more than once. For example, see this discussion in 2007. — Carl (CBM · talk) 02:15, 15 October 2009 (UTC)
Although I agree that the main proof should be the one in the article, I do like Likebox's computer-sciencey proof. Maybe there's some way to have Likebox's proof too, without having it as the main proof in the article? Or perhaps put it in the Proof Sketch article, as an alternative proof sketch? --Robin (talk) 02:18, 15 October 2009 (UTC)
Even if we did want to include Likebox's proof in the article, we would need to rewrite it significantly to fix the terminology to match the literature, and to make the tone encyclopedic rather than pedagogical. Based on past experience, I do not believe Likebox accepts such rewrites. — Carl (CBM · talk) 02:26, 15 October 2009 (UTC)
Right, I agree with you. I have no prior experience with Likebox, so I can't say anything about the problem you mentioned. I have seen a CSish proof of Godel's incompleteness in Scott Aaronson's lecture notes. Perhaps this will help? --Robin (talk) 02:41, 15 October 2009 (UTC)
The proof that Likebox is inserting is actually the same as the proof already there, just rephrased to use words like "program" and "quine" (the latter incorrectly). If we were to rephrase Likebox's proof into standard terminology it would simply be the usual proof via the diagonal lemma. This is the proof presented by mainstream mathematical logic texts. This has been explained to Likebox before. — Carl (CBM · talk) 02:49, 15 October 2009 (UTC)
I see what you're saying. This explains the fact that there aren't a multitude of texts out there with Likebox's proof: because both proofs are essentially equivalent, and after formalizing Likebox's proof, you end up with something similar to the original proof. --Robin (talk) 03:41, 15 October 2009 (UTC)

Note: I have posted about this to [1]. — Carl (CBM · talk) 02:26, 15 October 2009 (UTC)

There is no OR in this proof, it is equivalent to standard proofs, as CBM has said. The issues are with what type of material can be included here.
To Robin: the reason the proof is not presented the way I present it is not because it is harder to formalize. The proof I give is at least as simple to formalize as standard proofs. It's a little easier, in fact, because the formal structure of modern computers is already well understood.
But even though the logic is equivalent, style is very important. The style of proof that I gave, now presented on Godel's incompleteness theorems talk page, is vastly easier for undergraduates and non-specialists to understand. It is also easier for most specialists to understand, especially regarding Rosser's proof (which is a notorious sticking point for students). In my experience, a presentation of the proof in this style takes about 10-20 minutes to fully internalize and understand, while the standard presentations take days or weeks of intensive study to fully understand. Needless to say, learning the easy proof allows students to then understand the standard proof much more quickly. The proof I gave can be understood by any layperson who is somewhat familiar with mathematics.
If you support the material, realize that politics is now slightly against these types of proofs. There are two editors, CBM and Arthur Rubin, who oppose this material. They oppose it mostly by inertia, this is not the first time I have tried to incorporate the material. It requires more editors with a strong opinion for inclusion to get this material into the article.Likebox (talk) 20:40, 15 October 2009 (UTC)
I see no compelling reason not to use the standard proof (not the Likebox version) 16:28, 16 October 2009 (UTC)
After a long discussion with Likebox and CBM, I also feel that we should use the standard proof (the one that appears in text books). --Robin (talk) 17:06, 16 October 2009 (UTC)
Silly people--- have you not read the proofs? What is this? The quine presentation of Godel's theorem is 10 times better, and it does not replace the other proof, it augments it. I don't understand why opinion here swings one way, and opinion of people I talk to in person swings the other way. It's definitely odd.Likebox (talk) 03:35, 19 October 2009 (UTC)
The difference is probably that here, you are running into people that are more than capable of being your intellectual equal, versus your students, no matter how bright, are going to be very easy to convince of anything you like. Indeed, I just convinced a class for a few minutes at least that there is actually an inconsistency in Peano arithmetic but that there is an adult conspiracy to keep this hidden from children until the contradiction becomes too obvious after you learn about complex numbers (no, I'm not joking). --C S (talk) 11:31, 21 October 2009 (UTC)
I realize the point of your post was to say why people here might respond differently than students, and I agree with your assessment about that, but I am uncomfortable with threads discussing who is the intellectual equal of whom. I think that the main reason for us to focus on what the sources say, even when we have articles written by experts in the field, is so that we can avoid having to make these sorts of comparisons. Of course if you ask three experts to write an article from first principles, you will get disagreements and arguments about the best way to present the material. This is why there are so many books on elementary group theory, elementary real analysis, etc., and it is why the Bourbaki project is so remarkable. But if you ask three experts to write an article that simply condenses and summarizes the existing literature, without adding any personal interpretation of how the literature "should be", they can do this with much less difficulty. — Carl (CBM · talk) 12:37, 21 October 2009 (UTC)

Because Likebox has added the proofs again after the discussion here and at WP:NORB was clearly against them, I have raised the matter here. Comments from all users are welcome there, despite the name of the page. — Carl (CBM · talk) 00:48, 19 October 2009 (UTC)

Here's the correct link: WP:ANI#User:Likebox and tendentious re-insertion of original research. — Emil J. 12:12, 19 October 2009 (UTC)

### An article on computing theory based proof?

I am not keen on having the computer type proof in the Godel article, but I think the approach is I believe notable because a number of people have used it and it does convey the underlying ideas nicely. Can't say either I like the 'it is obvious that' in the text Likebox put in but there may be a way to show the status of things like that.

-- Perhaps it should be called an advanced proof in the tradition of 'Advanced algebra' and 'Elements of number theory'. ;-) Dmcq (talk) 13:53, 21 October 2009 (UTC)

Oh dear. I've had a good read of that ANI and it all reminds me of WP:The Truth. Dmcq (talk) 14:27, 21 October 2009 (UTC)
The main difficulty with Likebox's proof is that there really are not sources for it as it is literally written, but once one changes back to standard terminology, the proof is already described in Gödel's incompleteness theorems in the section "Relationship with computability".
There are two "regular" ways of presenting a proof of the incompleteness theorem via computability, which are actually very similar to each other:
1. Via the fact that any consistent, computable extension of Robinson arithmetic is incomplete; this is the method used by Shoenfield in Mathematical logic. A weaker version is given by Enderton in A mathematical introduction to logic. This method is characterized by its use of the fact that a consistent, complete, computably axiomatized theory is decidable. It is also characterized by the fact that it does not produce any concrete Gödel sentence.
2. Via Kleene's T predicate, which is used to replace the provability predicate in what is essentially a rewrite of Gödel's syntactic proof. This gives a refinement of the first method, in which the Gödel sentence can actually be written down. Kleene uses this method in Introduction to metamathematics.
Likebox's text is, in the end, a rewording of the second method into idiosyncratic terminology. It would be possible to reword the proofs to make the terminology standard, but Likebox has argued against that because he claims that the standard terminology is bad and should not be used. — Carl (CBM · talk) 14:53, 21 October 2009 (UTC)

## Differential algebraic equation

The article says:

In mathematics, differential algebraic equations (DAEs) are a general form of differential equation, given in implicit form. They can be written
${\displaystyle f\left({\frac {dx}{dt}},x,y,t\right)=0}$
where
• ${\displaystyle x}$, a vector in ${\displaystyle R^{n}}$, are variables for which derivatives are present (differential variables),
• ${\displaystyle y}$, a vector in ${\displaystyle R^{m}}$, are variables for which no derivatives are present (algebraic variables),
• ${\displaystyle t}$, a scalar (usually time) is an independent variable.

I was expecting next to see the most important part:

• ƒ is [.....]

My guess was that ƒ was to be a polynomial function and that justified the word "algebraic". Or maybe ƒ is a function defined implicitly by polynomial relations. Or something. (?) Michael Hardy (talk) 04:04, 20 October 2009 (UTC)

It appears they mean "algebraic" as opposed to "differential" (rather than as opposed "transcendental"). As in you have a constraint, say f(w,x,y,t)=exp(xyzt)-5=0, and you plug in w=dx/dt, making the normal (in their terms "algebraic") equations f(w,x,y,t)=0 a differential equation. So you get a differential, algebraic equation. The first few hits on google books use differential-algebraic equation (with a hyphen), btw. RobHar (talk) 04:17, 20 October 2009 (UTC)

But if that's what it means, then what would be an example of a differential equation that is not of the kind this is about? Michael Hardy (talk) 20:09, 20 October 2009 (UTC)

Is this subject even notable? I see only one reference and that's from a research paper. My thinking is to solve the problem by PRODing the article, but maybe someone will find a secondary source before it comes to that.--RDBury (talk) 19:13, 20 October 2009 (UTC)

Articles that link to it are not citable evidence of notability, but maybe they give clues about where to look for such evidence. Michael Hardy (talk) 20:08, 20 October 2009 (UTC)

Please PROD Pantelides algorithm, someone. (The guy once interviewed me for a job, and I'm still annoyed about how it went.) Charles Matthews (talk) 20:12, 20 October 2009 (UTC)
Pantelides Algorithm is used in Modelica and was extended by Pryce/Nedyalkov. Whereas I nowhere found a readable description of Pantelides, the Pryce variant is easily understandable. The article as it is is useless, perhaps add the references to DAE. DAE themselves have huge applications in electrical circuit simulation, chemistry and classical physics. The standard pendulum example and a discussion of the different index concepts are the most obvious points missing.--LutzL (talk) 16:45, 21 October 2009 (UTC)

## Markov chain

See talk:celebrity name game. I find the assertion that it's a Markov chain questionable. Apparently it was put there in June 2008 by user:Rdbrady. A few days ago, someone added Category:Markov models and that made the article appear in this WikiProject's new articles list. That's how it came to my attention. Michael Hardy (talk) 19:14, 21 October 2009 (UTC)

Is the article even notable? Doesn't this game have a more generic name which might have its own WP article? --Robin (talk) 19:37, 21 October 2009 (UTC)

OK, I've deleted the Markov chain claim. I'd have done that earlier if I hadn't been somewhat rushed. Michael Hardy (talk) 21:28, 21 October 2009 (UTC)

## Errors in polyomino diagrams

The diagram File:Heptominoes.svg in Heptominoes contains two identical forms. Since the symmetry discussion in the article relies on the diagram, there might be additional errors.

The diagram File:All 369 free octominoes.svg, along with the symmetry discussion, was removed from Octomino since the diagram contains two heptominoes.

Both errors are described on the respective image pages. Does anyone know enough about polyominoes to fix this? Thanks --ἀνυπόδητος (talk) 10:38, 25 October 2009 (UTC)

I seem to remember figuring out heptominos about 30 years ago (or maybe I only got up to hexominos). I'm sure there are web sites that list them; I'll keep an eye out.--RDBury (talk) 19:21, 25 October 2009 (UTC)
Actually the Mathworld site lists them. It'll take a while to compare the diagrams and I'm busy today. But I'll do it when I get a chance assuming no one else does it first.--RDBury (talk) 19:26, 25 October 2009 (UTC)
The missing heptomino looks like this:
  X
X X
X X
X
X

In other words this one is missing and should replace one of the duplicates. Note that it's only off by one. I checked the rest as well and it looks like they're ok. I'm trying to use Inkscape to fix the image but it looks like it was originally created using a different program so it's proving to be a strain on my somewhat limited graphics skills. I haven't started on the octominoes, not 100% convinced it's worth the effort.--RDBury (talk) 03:57, 26 October 2009 (UTC)
It would probably better to manually edit the source code: more accuracy and less chance of messing up the code. I can probably do that, the only problem is to find the crucial heptomino in the code. --ἀνυπόδητος (talk) 07:43, 26 October 2009 (UTC)
Done --ἀνυπόδητος (talk) 18:16, 27 October 2009 (UTC)
By the way, the Domino article is just a redirect to Dominoes which has a single sentence on the mathematical object. Any thoughts on a Domino (mathematics) article?--RDBury (talk) 04:59, 26 October 2009 (UTC)
I started it, more or less based on Tromino. Is there anything else to say? --ἀνυπόδητος (talk) 07:43, 26 October 2009 (UTC)
The most notable problem that I've seen with dominoes is colouring a chessboard with the two opposite corners removed. There's interesting tiling problems with trominos as well. You can get some nice Aha! proofs. Tiles often seen to be referred to as dominos in maths, I haven't the foggiest why. Dmcq (talk) 08:05, 26 October 2009 (UTC)
This wider sense of domino=tile should go into the article. Can you source that? --ἀνυπόδητος (talk) 09:49, 26 October 2009 (UTC)
Actually wikipedia has a page Domino problem which shows exactly this. Dmcq (talk)

## Flexagons

I am trying to clean-up our article on flexagons, as it is mostly a how-to. As part of this, I am trying to include a formal definition and I hope that in the future the article can include a full mathematical formalization of flexagons. Unfortunately, I am having a little trouble understanding the various definitions (I feel like I understand them, but when I try to explain them in my own words, I am at a loss.) So I would appreciate it if someone could help me understand and word this correctly. I am rewriting it at User:Jkasd/Misc_draft, feel free to edit that page directly. Jkasd 00:13, 26 October 2009 (UTC)

If you're rewriting the article, why is there nothing in the last month on Talk:flexagon? It would be best to work with the editors of that page, rather go off and do your own re-write. Dicklyon (talk) 02:27, 26 October 2009 (UTC)
Well I briefly mentioned my intent on the talk page. But you're right I should have mentioned it there first. It seems that that page does not receive much traffic however. Which is why I brought it up here first. Jkasd 02:51, 26 October 2009 (UTC)
If there's not much traffic, you should have no trouble working on it in place. There's almost never a good reason to do an article revision in your own sandbox. Dicklyon (talk) 02:54, 26 October 2009 (UTC)
I guess not. I traditionally have enjoyed creating articles in my user space before changing the actual article, so I guess I should change my habits. Jkasd 02:58, 26 October 2009 (UTC)
My main reason for doing so was that I find information about a subject in small bits, and it takes time to make it into a complete sentence, so I liked to have a complete thought before posting it in an article. Jkasd 02:59, 26 October 2009 (UTC)
There is a lot of how-to in the article, but I think a certain amount is necessary to understand the subject, especially since, as recreational mathematics, it should be accessible to a general audience. So I don't think a complete rewrite is called for. Also, speaking as someone who's done a fair share of heavy editing (e.g. I did about 90% of Trisectrix of Maclaurin), I have to agree with Dicklyon on the sandbox idea. The reason to edit an article in your sandbox is to keep the cruft hunters from pouncing on it while it's still an embryo; that shouldn't be a problem with an existing article.--RDBury (talk) 05:36, 26 October 2009 (UTC)
That's a good point, but I think that there is more than necessary as the article now is. That was the original purpose of my draft pages, so I will limit my use of them only when that applies. Jkasd 06:19, 26 October 2009 (UTC)
I'm a bit worried by this "I am trying to include a formal definition" aspect. That sounds like original research to me which is frowned up in peoples contributions to wikipedia. By the way you might be interested in rigid origami Dmcq (talk) 08:16, 26 October 2009 (UTC)
No no, I am trying to remove original research and add verifiable content. Flexagons have been mathematically abstracted and formally defined by several reputable sources such as here and here. This information is encyclopedic and thus should be included in the article. Jkasd 08:30, 26 October 2009 (UTC)
Oh very good, sorry, thanks for that Dmcq (talk) 09:16, 26 October 2009 (UTC)
It looks like most of the 'how to' aspect can be removed by simply changing to a passive voice instead of saying 'you'. Dmcq (talk) 09:22, 26 October 2009 (UTC)
Yes I think that changing the voice would fix that. Still, probably only the hexahexaflexagon example should be given. Jkasd 09:33, 26 October 2009 (UTC)

## Notability of certain positional numeral systems

For anyone who is interested, there is a discussion Category talk:Positional numeral systems as whether certain articles, such as Quinary meet notability guidelines.--RDBury (talk) 17:39, 28 October 2009 (UTC)

## RFC to rename e from constant to number

There is an RFC discussion to discuss moving E (mathematical constant) to E (number). Johnuniq (talk) 07:04, 29 October 2009 (UTC)

I don't think it is an E number! ;-) Dmcq (talk) 16:34, 29 October 2009 (UTC)

"e (number)" seems somewhat preferable because it's simpler.

(And notice that lower case should be used. This is one of those articles whose titles have a lower-case initial letter; an exception to usual Wikipedia usages.) Michael Hardy (talk) 17:57, 29 October 2009 (UTC)

## Pentagram

This article seems to be an odd juxtaposition of occultism and mathematics. The article seems to have been split and re-merged without much discussion either way. Any thoughts on whether "Pentagram (geometry)" should be a separate article?--RDBury (talk) 14:53, 29 October 2009 (UTC)

I don't see the problem with a unified article, covering both the math and occult aspects; sort of like golden ratio. Dicklyon (talk) 16:00, 29 October 2009 (UTC)

## Help with citations

Hi: Is there some sort of automated tool to convert data into citations? MathSciNet will output the data as our choice of EndNote, BibTeX, and AMSRefs, but I'm still having to do a lot of copy/pasting, which is annoying. Thanks, RayTalk 01:57, 30 October 2009 (UTC)

I do it all by hand too. -- Avi (talk) 02:03, 30 October 2009 (UTC)
There is http://zeteo.info, created by Jakob.scholbach. In addition to having a database of citations taken from our from math articles, it can convert BibTeX to wiki code. — Carl (CBM · talk) 02:19, 30 October 2009 (UTC)
Thanks Carl. That's exactly what I was looking for. RayTalk 03:27, 30 October 2009 (UTC)