Wikipedia talk:WikiProject Mathematics/Archive/2005/Sep-Oct

message: There's some fairly good work on WP about determinacy, but it's a bit haphazard.  The axiom of determinacy article doesn't explain very clearly what a game or a strategy, or in particular a winning strategy, is.  Winning strategy itself tries to be all things to all people.  See my remarks in Talk:Axiom of determinacy and Talk:Winning strategy#Organizational questions for some thoughts with no clear conclusions, but I think a good starting place for trying to get the (nonexistent) category into better shape.
A couple of things of which I recently became aware have given me a little more sense of urgency about this.  There's a Wikipedia:WikiProject Game theory, and they added winning strategy to it, which may be appropriate if that article should be ceded to the game theorists, and another written for the determinacy theorists (I'm thinking of writing a Game (set theory) article to subsume a whole bunch of these things, and change links from other articles to it).  See my remarks in User talk:Kzollman#Game theory wikiproject.
Also there's apparently a category, :Category:Combinatorial game theory, which deals with John Horton Conway type games.
I think this needs to be sorted out before it becomes an irretrievable mess.  Would anyone be willing to work on a Wikipedia:WikiProject Determinacy?
----
On further reflection, I think the central article of the Determinacy category should just be called Determinacy.  It's a much more general topic than Axiom of determinacy, which currently serves the purpose of a central reference point.  You can see an outline at User:Trovatore/Sandbox/Determinacy.  --Trovatore 01:45, 2 September 2005 (UTC)
replies: text: So the article is far from finished, but there's enough there to put it in article space I think, and I've done so. --Trovatore 04:33, 2 September 2005 (UTC)
thread_title: Games and determinacy

message: I am vaguely thinking of starting an insane and hopeless task, and that is to create a page listing low-dimensional, non-supersymmetric Lie groups and algebras, thier properties, isomorphisms, topologies, etc.  I despair, because this seems like a collossal project trying to describe a hopelessly tangled web of inter-relationships. I was irked because what I really wanted was a list of (examples of) infranil manifolds. Any suggestions on how to minimize the pain and maximize the gain? linas 15:19, 6 September 2005 (UTC)
replies: text: There is also table of Lie groups which I somehow blindly didn't see at first.  linas 04:37, 7 September 2005 (UTC)
thread_title:  Table of Lie algebras & groups 

message: Do we have a specific math article on Omega? The specific one that states that mathematics can't be strung together and that discoveries are just luck? It also states that its goal is to try and find the halting possibility of a computer when faced with an infinite answer.
:Omega doesn't "say" that; it's just a number. But Wikipedia does have an article on it: Chaitin's constant. — Nowhither 00:11, 10 September 2005 (UTC)
thread_title:  Omega? 

message: I like Linas' suggestion at least in principle (with the caveat that it not become an excuse to avoid adding motivation to articles).  I'd suggest further that there be a uniform naming scheme for the simpler articles, say Foo (introduction) or Foo (elementary) for the beginners' version of Foo.  But it does seem like something of an "unfunded mandate"; I'm not personally volunteering to produce these articles for the hundreds if not thousands of topics that'd need them.  Any further thoughts?  I hate to see the matter just dropped, without a clear decision. --Trovatore 20:13, 13 September 2005 (UTC)
thread_title: So what's the plan?

message: As a less radical measure, how about updating just the introductions of some of the math articles to be more accessible.  For instance, something to the effect of:
:The Riemann Zeta Function is a mathematical function discovered by Whatever-his-first-name-is Riemann in 1822.  It is important in number theory because it demonstrates some property of prime numbers, as was proven in 1903 by whoever.
: < template of some sort > 
: What follows is a technical discussion of the properties of the Riemann Zeta Function.  This discussion assumes familiarity with meromorphic functions, the Euler Product Formula, basic forcing, and whatever else.
: < / end template >
-- Avocado 21:29, 13 September 2005 (UTC)
thread_title: One more idea

message: From the back-jacket information for Itay Neeman's book on The Determinacy of Long Games, which I will likely cite:
: The book is largely self-contained. Only graduate level knowledge of modern techniques in large cardinals and basic forcing is assumed.
--Trovatore 18:41, 11 September 2005 (UTC)
replies: text:  That's a good one! Only very basic forcing is assumed, right? As far as I am concerned it means that I will have no clue whatsoever about the very first section in the book. :) Oleg Alexandrov 23:04, 11 September 2005 (UTC)
replies: text:  That's cute. FWIW, I know a Ph.D. student who did his dissertation on forcing. Apparently the first question at his defence was, "So, what's 'forcing'?" He said he immediately knew he was going to pass. — Nowhither 03:00, 12 September 2005 (UTC)
thread_title: It's all a question of perspective

message: And, speaking of RfC, one of the topics there is: 
:Was Bertrand Russell Welsh and does he belong in Welsh Wikipedia:categories? (He was born in Monmouthshire, and lived there until his parents died - when he was four.) 
I'm not making this up; if anyone has an opinion on the matter (I did) do go share it with Talk:Bertrand Russell; maybe we can drown out the various contending nationalisms. Septentrionalis 22:46, 12 September 2005 (UTC)
thread_title: Was Bertrand Russell Welsh?

message: Hello,
Please notice this project. 
I hope that the List of publications in mathematics, List of publications in statistics and List of publications in computer science will be adopted by the mathematics project.
Thanks,APH 06:48, 13 September 2005 (UTC)
thread_title:  [[Wikipedia:WikiProject Science pearls| Science pearls]]

message: It seems to me that the article on logical converse is incomplete.  It has the schoolbook definition of the converse, which is that the converse of a statement of the form (A → B) is the statement (B → A).  But I think that "converse", as the term is used by mathematicians, is actually a more subtle and complex concept.   I've put some simple examples at Talk:Converse (logic).  
I think that if we actually look at examples, we'll find all sorts of different forms that the converse can take, and that this information should be incorporated into the Converse article.  
I hope people will assist me in this.  -- Dominus 13:32, 14 September 2005 (UTC)
thread_title:  [[Talk:Converse (logic)|Converse]] 

message: Indicial Calculus claims that it is "the calculus used to extract root indices of order x, where x is an element of a Galois splitting field for a given polynomial equation P of ductivity D[P, 0] = 0." Does this ring a bell to somebody? The reference to "Little Bride Bonnie (1859-1941), a German mathematician known for early work in group theory" made me suspicious, and a quick search on MathSciNet and Google didn't yield any results. -- Jitse Niesen (talk) 21:18, 15 September 2005 (UTC)
replies: text: The intro, as phrased, is nonsense: whatever a root index is, its order shoulc be an ordinal, not an element of a Galois field. Constructing a cube of side e (next paragraph) is trivially equivalent to constructing a segment of length e. I've never heard of ductivity, either. Septentrionalis 01:21, 16 September 2005 (UTC)
replies: text:  A mathematician Little Bride Bonnie is mentioned there. From what I know, Bonnie is a girl's name. Equivalently then, the name of this German mathematician is Little Bride Mary if you wish. BJAODN. Oleg Alexandrov 02:06, 16 September 2005 (UTC)

text: No paper by Hinkle is in Jahrbuch über der Fortschritte der Mathematik for 1899-1901. Hoax. AfD, IMO. Septentrionalis 05:00, 16 September 2005 (UTC)
replies: text: Bonnie (also spelled bonny) means pretty, as in "my bonnie lass" and brides are often referred to as bonnie (search Google for "bonnie bride" or "bonny bride"). Paul August ☎ 05:47, 16 September 2005 (UTC)

text: I did some digging and posted my impressions on the talk page. Especially, the index calculus algorithm is frequently cited in cryptography. Given the existence of that page, even if Indicial Calculus is meant to be legitimate its page should not exist. --KSmrqT 11:49, 16 September 2005 (UTC)
thread_title: Indicial calculus

message: See discussion at Wikipedia talk:Requested articles/mathematics#MathWorld?. Comments welcome. Oleg Alexandrov 03:20, 16 September 2005 (UTC)
thread_title:  List of mathworld's math articles 

message: ... We will find out. Wikipedia:Articles for deletion/Mark Schmitt. Oleg Alexandrov 02:01, 17 September 2005 (UTC)
thread_title:  Is a high school math teacher who got a prize for undergraduate paper notable enough? 

message: Anybody heard of the "corank" of a Lie algebra? An anon replaced "rank" with "corank" at Affine Lie algebra, and I don't know if that's correct or not. Oleg Alexandrov 16:06, 18 September 2005 (UTC)
replies: text: I'm watching that one, I think that's rigt, that's what makes it affine. But not sure; I was going to read on the topic (quantum groups) this summer, but got distracted. Maybe next summer. Its a pretty advanced topic, mostly just string theorists live there. linas 04:41, 20 September 2005 (UTC)

text: The "corank" here refers to the generalized Cartan matrix, the dimension of its null space. However, neither choice seems to agree with the definition already in place at the end of the Kac-Moody algebra page. The symmetric factor of the matrix is there required to be positive semidefinite, which does not place such a stringent restriction on either rank or corank. Even knowing almost nothing about the topics it appears that something is amiss. If someone wants to dig further, a standard reference book seems to be Victor G. Kac's Infinite-Dimensional Lie Algebras, 3/e, CUP 1990,  (paperback: ). Or ask your friendly neighborhood string theorist. --KSmrqT 06:53, 20 September 2005 (UTC)
thread_title:  Note for Lie algebra specialists 

message: Just a reminder that when you've guessed the name of an article you're linking to, and it comes up blue and you save your edit, it's worth clicking through to those links and seeing if they say something sensible and relevant to the meaning you have in mind.
I happened across a page called complete Boolean algebra that had some trivial nonsense in it, nothing to do with CBAs, yet it was linked to from complete lattice.
Another possibility is that the link from "complete lattice" was originally red, and then someone came along and filled in the incorrect "complete Boolean algebra" page. To protect against this sort of thing, click through to your redlinks and add them to your watchlist (yes, this works). --Trovatore 17:32, 19 September 2005 (UTC)
replies: text: One can also check Wikipedia:WikiProject Mathematics/Current activity for incoming stuff. Oleg Alexandrov 04:35, 20 September 2005 (UTC)
thread_title: Check those links

message: Our articles Isometry and Metric space have different definitions of isometry. The former requires an isometry to be onto, the latter does not. There is a discussion at Talk:Metric_space#Isometry, about which is more standard, and what we should do about it. Please share your thoughts there. Thanks Paul August ☎ 16:38, 22 September 2005 (UTC)
thread_title:  What is an Isometry? 

message: What are the prospects for commuting diagrams in TeX on WP? Most pages  that have them seem to have custom-generated PNG's.  My attempts to create a native diagram result only in ugliness:
:\begin{matrix} 
K & \begin{matrix} 1_K \\ \longrightarrow \end{matrix} & K  \\
\downarrow^{\eta_A} & \, & \eta_B \downarrow \\
A &  \begin{matrix} f \\ \longrightarrow \end{matrix}  & B 
\end{matrix}
and a triangle:
:\begin{matrix} 
&& K &&   \\
& \swarrow^{\eta_A} & \, & \eta_B \searrow & \\
A &&  \begin{matrix} f \\ \longrightarrow \end{matrix}  && B 
\end{matrix}
The markup is complicated too ... Any better way of doing this? linas 00:01, 26 September 2005 (UTC)
replies: text: Yes, it would be nice if the powers that be included some diagram package into the wiki math code. I generate PNG's using a program called textogif and just upload them. It is fairly fast and painless once you have it all set up. Check out my page on Wikimedia Commons. I have some minimal set of instructions there. -- Fropuff 16:26, 26 September 2005 (UTC)
replies: text:  I thought one can use xypics to create diagrams. This is a LaTeX package. So, all needed is for the Wiki TeX dialect to support this package. I also wish that Wiki TeX also supported the amsart package, as when we copy articles from PlanetMath as part of the WP:PMEX project, often many TeX symbols are not recognized. Oleg Alexandrov 17:36, 26 September 2005 (UTC)
thread_title:  Commuting diagrams?  

message: The article manifold has been rewritten at manifold/rewrite. Manifold/rewrite has had around 225 edits since June 19 when Jitse started it as a text in his sandbox to offer some constructive suggestions to the arguments at talk:manifold. Now the rewritten article looks nice and needs to be merge into manifold, which itself underwent around 58 edits since June 19. The big question is, how to merge them? One can merge the edit histories, see  Wikipedia:How to fix cut and paste moves, but it could be a mess. The only other choice is I think to give up on the history of one of the two articles. What should be the right decision? Let us discuss this at talk:manifold/rewrite. Oleg Alexandrov 04:27, 26 September 2005 (UTC)
thread_title:  Merging [[manifold]] and [[manifold/rewrite]] 

message: See Wikipedia:WikiProject_Stub_sorting/Proposals#More_Math_stubs. Oleg Alexandrov 00:51, 27 September 2005 (UTC)
thread_title:  Comments requested on new proposed math stub names 

message: At Talk:Birthday paradox it is being proposed to delete from the article the section on Paul Halmos' view of the matter.  That is the only section that takes the reader beyond the stage that any freshman who thinks the problem through would figure out.  It's a fairly short section.  Three Wikipedian support deletion; only I have opposed it.  Would mathematicians please comment at Talk:Birthday paradox? Michael Hardy 22:41, 2 October 2005 (UTC)
replies: text: Oh:  It's the part labeled "long, windy, not needed". Michael Hardy 22:42, 2 October 2005 (UTC)
replies: text: ... and now I've changed the title of that section of that long talk page, to make it easier to find. Michael Hardy 22:44, 2 October 2005 (UTC)
thread_title:  Controversy over the [[birthday paradox]] article 

message: Paskal's triangle has been moved to Khayyam-Pascal's triangle. It is claimed there now that the latter is the internationally recognized name. Discussion is welcome at Talk:Khayyam-Pascal's triangle. Oleg Alexandrov 21:35, 5 October 2005 (UTC)
replies: text: Oh, just move back. We use the common name. The history can be dealt with in the article. This is the standard way. Charles Matthews 21:38, 5 October 2005 (UTC)
replies: text: Your wish is my command, so I moved it back. -- Jinn Niesen (talk) 23:16, 5 October 2005 (UTC)
thread_title:  [[Khayyam-Pascal's triangle]] 

message: The  template pops up every now and then at Wikipedia:Manual of Style (mathematics) and is there now. I would argue that it is unnecessary. Its only purpose is for a user to hop from manual of style to manual of style, but for people who actually use a particular manual of style, like our math manual, the links to the manual of style about writing China-related articles, how to write footnotes, etc, are not be helpful. I would argue that a link to the Wikipedia:Manual of Style on top of our manual of style should be enough. From there, one can access any other style manual if one wishes so. Wonder what people think. Oleg Alexandrov (talk) 04:12, 7 October 2005 (UTC)
replies: text: Harmless; and if we  remove it, it will be back. Why bother? Septentrionalis 20:03, 7 October 2005 (UTC)
thread_title:  The {style} template 

message: I posted a note on this guideline's talk page proposing a change in this policy (Wikipedia talk:Make technical articles accessible). --- Charles Stewart 02:22, 8 October 2005 (UTC)
thread_title: [[Wikipedia: Make technical articles accessible]]

message: Please vote at Wikipedia:Featured list candidates/List of lists of mathematical topics.  Otherwise, the issue may be decided by (from the looks of it at this time) people who never heard of mathematics until they saw this nomination. Michael Hardy 03:35, 13 October 2005 (UTC)
thread_title: Please vote on ''list of lists'', a featured list candidate

message: I am attending an AMS sectional conference this weekend, and once again listening to everyone complain about how badly math is taught in the US, how lousy all the grade school textbooks are (except the Singapore textbooks), and how the three big textbook publishers are so powerful that nobody has a ghost of a chance of making things better.  
Naturally, I thought of Wiki.  
What I propose is a series of articles on mathematics written at the grade school level, so students and teachers who actually care about mathematics can have at least one source to which to turn.  
I'm going to start at Grade school mathematics and take it from there.
Want to help?
Rick Norwood 22:46, 15 October 2005 (UTC)
replies: text: I would like to help, but think a problem needs to be addressed first: stability.  A book written by committee, and constantly changing, will be as bad as what's out there now.  We would need to have one committed person in charge, who could review potential contributions from many authors and decide which to include as is, which to include with changes, and which to reject.  This is rather "anti-wiki" so may not work here.  That said, I suppose we could write many articles within the current structure with the goal of copying them and making them uniform, outside the wiki structure, to make a textbook, at some future date. StuRat 23:24, 15 October 2005 (UTC)
replies: text: Agree w/StuRat on this point. I'm finding that WP articles tend to be "average" and not "excellent" because the excellent material in WP tends to get edited to oblivion.  For a reference, such as WP, that's fine. For a textbook, which you learn from, "average" is not good enough. A better model is the Linux kernel, where an authoritarian few act as gatekeepers to contributions.  linas 19:12, 16 October 2005 (UTC)

text: The first task, I would think, would be to come up with an ordered list of topics to be covered, by age group.  A grade school book should have lots of colorful illustrations, so having a graphic artist on the staff would sure be a good idea. StuRat 23:31, 15 October 2005 (UTC)

text: Also, you should set up a project page for this, so discussion can take place there. StuRat 23:32, 15 October 2005 (UTC)

text: We have Wikibooks, with a few mathematics texts there already. See http://en.wikibooks.org . Educational material should go there and not in Wikipedia. Dysprosia 00:44, 16 October 2005 (UTC)
replies: text:  Agree with Dysprosia. Wikipedia is for reference, it is a collection of encyclopedic essays. I am getting weary of people trying to use Wikipedia to fix the wrongs of the world. Oleg Alexandrov (talk) 03:53, 17 October 2005 (UTC)
replies: text: Yes, please support wikibooks. Charles Matthews 09:23, 17 October 2005 (UTC)
thread_title:  Wikitextbooks or www.yourbooksucks.com 

message: Just in case there are still Quantum and GR types lurking here, who haven't yet found Wikipedia:WikiProject Physics ... well, now you know: there's a physics project as well. Add your name to the list, and visit the talk page as well: I'm sure the topics are as lively and maybe more argumentative than those here! linas 00:28, 18 October 2005 (UTC)
thread_title:  Reminder: [[Wikipedia:WikiProject Physics]] !  

message: The common notation of a semidirect product seems to be G = N  H, with the normal subgroup at the left, while the symbol is a cross with a vertical bar at the right (see e.g. ), although the names of the symbols seem to suggest that the bar should be at the side of the normal subgroup (, ). Have other people any thoughts?--Patrick 13:37, 20 October 2005 (UTC)
replies: text: Perhaps it would be better to redirect such a specific discussion to Talk:Semidirect product? --KSmrqT 19:23, 20 October 2005 (UTC)
thread_title:  Semidirect product symbol 

message: The main article was moved, but the two subpages weren't. differentiable manifold, topological manifold redirect there. Admin privileges probably needed, since I couldn't do it. --MarSch 11:14, 20 October 2005 (UTC)
replies: text: I will take care of this now. Oleg Alexandrov (talk) 11:20, 20 October 2005 (UTC)
replies: text:  Done. I also merged their edit history with the corresponding ancient redirects created by Toby Bartels in 2002 or so. Oleg Alexandrov (talk) 11:27, 20 October 2005 (UTC)
replies: text: Thanks --MarSch 11:37, 20 October 2005 (UTC)
thread_title:  move of manifold/rewrite/* 

message: This is not about math, but might be helpful to the fellow mathematician. I found a very userful tool in my opinion, Pilaf's Live Preview at Wikipedia:Tools#Alternative_previews. It allows one to do instant preview, without waiting for seconds or more after hitting the "Preview" buttion. It works by some javascript magic, and is just as easy to install as pasting several lines of text into a file and doing a reload of your preferences (control-shift-r for Mozilla, Ctrl-F5 in IE, and F5 in Opera). I already love this tool. :) Oleg Alexandrov (talk) 12:51, 25 October 2005 (UTC)
replies: text: Note that it does not do LaTeX formulas, and does not show redlinks as red (one needs to check with the server for things like that), so the good old preview is still needed, but it can still cut the number of times one needs to use the usual Preview button. Oleg Alexandrov (talk) 14:02, 25 October 2005 (UTC)
thread_title:  Live preview 

message: The article Differentiating Functions is on AfD (doesn't show up in the Current Activity page because it's not in any math category). The article is very badly written, though one editor seems to think it's more accessible than Calculus with polynomials, which I find hard to credit.--Trovatore 05:52, 28 October 2005 (UTC)
replies: text: What's the current activity page? -Lethe | Talk 06:15, 28 October 2005 (UTC)
replies: text: Wikipedia:WikiProject Mathematics/Current activity --Trovatore 06:23, 28 October 2005 (UTC)
thread_title: Differentiating Functions on AfD