User talk:Linas/Archive16

WikiProject Physics Poll[edit]

There is currently a poll about WikiProject Physics in general. Please take some time to answer it (or part of it), as it will help coordinate and guide the future efforts of the Project. Thank you. Headbomb {ταλκ – WP Physics: PotW} 18:20, 2 July 2008 (UTC)[reply]

Port of GMP to Cell/Cell 2 Processor[edit]

Hi Linas, A long time ago in a galaxy far away, I discussed this issue with you. This may now become a reality for reasons I'd like to discuss with you. Do you have an email address or other means of contact? Check out www.mpir.org where we have set up a project which will eventually contain the abovementioned port. If you follow the link to the developer mailing list you should be able to find messages from me and obtain my email address. Sorry we have to exchange email addresses like this these days. Regards, Bill Hart. 82.16.69.123 (talk) 22:33, 18 July 2008 (UTC)[reply]

Hi Bill, I'll try to reply by email. I'm working on other things these days, it seems unlikely I'd get involved in this project right now. linas (talk) 03:44, 22 July 2008 (UTC)[reply]

Whitney isomorphism and hypergraphs[edit]

Linas -

I'm an undergrad, interestingly enough (at least to me) at what appears to be your alma mater, doing a research project in algebraic graph theory for the summer and curious about a certain line it seems you wrote on the graph isomorphism page - namely, that "The Whitney graph theorem can be extended to hypergraphs." Is this something you've sussed out for yourself, or do you have a reference for this claim? If you came up with it on your own, do you think you could explain to me a little more rigorously what you mean? Because over this program, I've found people mean a lot of different things when they say hypergraph, and I'm having trouble recreating the conditions one should assume to get a nice correspondance like Whitney does for graphs. This is not strictly related to my research (and if it does tie in, you or whomever came up with it will of course be cited), but it's a powerful theorem for graphs and, a newly converted hypergraph enthusiast, my interest is piqued.

Thanks, Mica (talk) 15:08, 24 July 2008 (UTC)[reply]

Hi Mica,

"The Whitney graph theorem can be extended to hypergraphs." is a one-sentence summary of a large chunk of an article from the book by Claude Berge, Dijen Ray-Chaudhuri, "Hypergraph Seminar, Ohio State University 1972", Lecture Notes in Mathematics 411 Springer-Verlag. If I remember correctly, its in the very first article, by Berge himself, in the third section. The claim that this somehow generalizes the Whitney thm is Berge's own; I've just paraphrased. linas (talk) 17:14, 24 July 2008 (UTC)[reply]

BTW, if you can provide formal definitions, with appropriate references, for "all of the different things people mean by hypergraph", I would really appreciate that. The Berge book provides one definition, and all of the articles seem to more or less stick to it, I think. However, I've seen other, broader definitions; all of these were less formal, and were used in comp-sci texts that weren't really interested in formalities or advancing graph theory, and so are "unreliable". So, having a compare-n-contrast of alternate basic defn's of a hypergraph would be a good thing for this article to have. linas (talk) 17:22, 24 July 2008 (UTC)[reply]

Integrated banner for WikiProject Computer science[edit]

I have made a proposal for a integrated banner for the project here . I invite you for your valuable comments in the discussion. You are receiving this note as you are a member of the project. Thanks -- Tinu Cherian - 13:45, 3 August 2008 (UTC)[reply]

I have tried to explain further regarding reasons and advantages.Kindly have a look -- Tinu Cherian - 12:10, 5 August 2008 (UTC)[reply]

Question on Plouffe's Ramanujan Identities[edit]

Linas,

In the article with title On Plouffe's Rmanujan Identities mentioned some Riemann zeta series at odd integer values that were discoveried by Plouffe. I saw some of those similar series (but put in different form) that can be found in http://www.seriesmathstudy.com/mainright3.htm posted on Jan 16, 2006. I am curious to know the date that Plouffe had posted his discovery on these series. I am looking for inspired2.pdf file that you mentioned in References, and I haven't found it because the link was broken.

Can you help to provide information about the Plouffe's article for the discovery of his series?

Thanks,

Cindy —Preceding unsigned comment added by 65.246.157.99 (talk) 15:00, 8 August 2008 (UTC)[reply]

Hi Cindy,

I don't think Plouffe wrote an article, he just posted on the web, somewhere; isn't there a reference for that? I was somewhat naive; on closer inspection, these types of series are, for the most part, relatively straightforward to obtain from similar series that Ramanujan posted, although this is not apparent until *after* you do the work, and then go back and look. Plouffe had found the identities numerically, and offered no proof. I'd come up with a proof, but it turned out I was at least the 5th or 10th person to do so -- the identities stem from a general form that had been proved decades earlier, and had even been generalized to automorphic forms, and what not. This is actually pointed out in the preface to one of Ramanujan's notebooks, which says something like "Formula XXX is the most frequently rediscovered formula, having been (re-)discovered by Y in zzzz, and W in xxxx, etc." and so it seems I followed in that tradition.

Not to belittle the formulas given in the SMS web page you give; some may well be new. However, such formulas can be added, subtracted, multiplied and divided, yielding a very rich structure of similar relationships. Whether some are "new" or are just recombinations of known results are hard to tell at a glance. I would be much much more interested in seeing a description of the "generating set" of such formulas: a set of core identities, a "basis", from which all other identities can be obtained through addition and multiplication. Is such a basis countable or uncountable? etc. linas (talk) 16:44, 8 August 2008 (UTC)[reply]

Hello Linas, Thanks for your reply. I found the inspired2.pdf file from the site http://www.lacim.uqam.ca/~plouffe/inspired2.pdf, which mentioned Plouffe considered powers of exp(k*pi) instead of using previous way (exp(2*pi). This is the main key of his changes to figure other similary series of high powers using computer algebra system. There are innumerable numbers (uncountable) of such series existed. The ones you see in SMS web page are of odd alternative series, but this page displays only few of them.

Cindy. —Preceding unsigned comment added by 65.246.156.126 (talk) 17:32, 8 August 2008 (UTC)[reply]

Editing[edit]

Dear Linas,

I have encountered quite a few of your edits which have been misleading and incorrect. For instance, you wrote on the article, 'Prametric space', that:

If $(X,\rho )$ is a metric space, and $f:X\to Y$ is a map, then

d(y_{1},y_{2})=\rho (f^{-1}(y_{1}),f^{-1}(y_{2}))

is a symmetric prametric.

which is wrong. If the map is not surjective, then the preimage of some points may be empty; a prametric has to always be a binary operation and therefore there must be a real number (called the distance) associated with every two pair of points. If the map is not injective, then the preimage of some points may have more than one point; which distance do you use then? This example is correct if the assumption of bijectivity is added.

My apologies, my intent is not to mislead; perhaps I was sloppy or imprecise. As any other endevour, one must apply a modicum of common sense. You spotted a problem, and saw your way out of it; you say how to avoid the difficulty that you had. Perhaps other readers will be able to accomplish the same.

This is not the only mistake/misleading comment that you have made. You also wrote (and emphasised in quite a few articles), that the Hedgehog space is an example of a Moore space. Every metric space is a Moore space so this statement is trivial; why are you naming obscure examples of Moore spaces?

I don't remember why. It seemed important at the time.

Yet another mistake;

Please don't attack. You have yet to point out any mistakes at all. To write "yet another mistake..." is rather insulting.

you wrote that:

'L^p(S) is not contained in L^q(S) iff S contains sets of arbitrarily small measure'

is wrong. The statement is true and I am glad that someone appropriately corrected this.

No, you are wrong. I did not write this at all. I certainly did not modify the article to state anything like this. There was some confusion on the talk page as to some statements made in the article -- several parties in the conversation were confused about various issues at various points -- the confusion was aided by bad language, and by the accidental reversal of a few inequalities. I believe that the issues were eventually resolved. However, I did not edit the article, so please do not blame me for errors introduced.

Please give reasons for your edits; some of your edits seem to be evidently copied from books

No, they have not been. You're full of shit.

and you obviously have not thought about the edit before making it.

And you too apparently don't bother to think about what you write, before you splat bullshit onto user talk pages.

Apart from that, congratulations on doing such a good job and spending the time to edit Wikipedia!

Topology Expert (talk) 11:00, 25 August 2008 (UTC)[reply]

Yeah, fuck you too. I don't know what makes you think you can sit on such a high horse, criticize from afar, heap rudeness upon rudeness, and then have the gall to congradulate me and urge me on in my efforts. You speak with false and deceitful language. I don't know what you expected to accomplish with your post, but I can say that you managed to insult me and make me angry. Apart from that, I'm sure you're a great guy. linas (talk) 16:40, 26 August 2008 (UTC)[reply]

Hey[edit]

You too, and thanks for the great work on the articles about FSTs :) - Francis Tyers · 17:11, 5 September 2008 (UTC)[reply]

Welcome! (That's a finite state transducer, I guess, but I don't remember editing that article. I did hack on related articles though; including various monoid-related articles, culminating in what I thought was a pretty damned cool relationship being that between Cartesian closed category and lambda calculus! ) linas (talk) 21:07, 24 September 2008 (UTC)[reply]

Clutters[edit]

Hi Linas,

in fact, Sperner family and clutter are two names for the same object. Also, I think Berge called them something else in his book on hypergraphs. Also, I believe the blocker is correctly defined, and this is in fact another name for the transversal. From my writing..

the blocker of $H$ denoted $b(H)$ , is the clutter with vertex set $V$ and edge set consisting of all minimal sets $B\subseteq V$ so that $B\cap A\neq \varnothing$ for every $A\in E$ .

I'm working with simple hypergraphs, so I treat each edge as a subset of vertices. With this understanding, I believe the given description to be accurate and certainly not vague.. but perhaps you or someone else could improve it. The blocker is a new hypergraph, its vertex set is V and a subset of V is an edge of the blocker if it is minimal while meeting every edge in the original.

Another word about terminology here.. the term blocker was introduced by Edmonds and Fulkerson and is now the popular choice among people in the subject of combinatorial optimization (Seymour, Schrijver, Lovasz, etc). I'm not sure where Sperner Family is popularly used anymore, but I know that I have heard it here and there. —Preceding unsigned comment added by Mjaredd (talk • contribs) 01:39, 24 September 2008 (UTC)[reply]

Thanks. I think my remarks about "vagueness" had more to do with "how hard to I have to think in order to determine if this statement is true or not" -- it was probably more a comment about the clarity of the article, from the viewpoint of a newcomer. I'll have to look again. linas (talk) 20:59, 24 September 2008 (UTC)[reply]

Extending the GLE library[edit]

Linas, I am using GLE with modifications for writing out graphics elements to a renderer other than OpenGL. I added renderer callback hooks similar to those used in gluTess functions, and thought it migh tbe nice to incorporate this into the official GLE code.

Sorry to hear about your massive SPAM load. It's becoming a problem for everyone. What we need is to establish a network of trusted email servers that work together to block SPAM by a strict black-list policy that locks out any email senders showing signs of spamming, until they can show otherwise. I would rather have occasional temporary out-box blocks than the trouble if dealing with in-box filtering. As an entrepreneurial programmer, maybe this would be a worthwhile project.

User:Joekrahn on 24 Sep 2008 —Preceding undated comment was added at 16:19, 24 September 2008 (UTC).[reply]

Sorry I didn't reply earlier, I didn't spot this comment till just now. linas (talk) 08:04, 4 December 2008 (UTC)[reply]

Notability[edit]

Hi Linas. What you wrote on Director string last month made sense, and I brought it up on WP:NOTABILITY to get further feedback. Just to say: I didn't bring it up there with the intention of deleting Director string page! — I just wanted to discuss the general principle. Sam (talk) 21:38, 25 September 2008 (UTC)[reply]

can you respond[edit]

Can you respond to my at mixing. Thanks PDBailey (talk) 01:29, 24 October 2008 (UTC)[reply]

I gave a very long response, I hope it's what you were fishing for. Once, again, these are very very advanced topics, and you are missing a lot of pre-requisites for understanding them; they require not only a good undergraduate training in mathematics, but also a fair amount of specialization in grad school. I simply don't have the time or energy to tutor you in the basic background needed to understand this topic, and there is no particularly simple or intuitive way to communicate the basic ideas. Not all WP articles will be accessible to all readers, sorry. linas (talk) 04:39, 24 October 2008 (UTC)[reply]

Linas, I appreciate you taking the time to explain these topics to me, but I think you are making one dire error. you might want to avoid imputing peoples backgrounds. As an example, when someone writes, as you did, "For quantum mechanics, [the probability measure is] the square of the wave function." the reader could impute that they do not understand the concept of complex conjugate, or that the author has never actually found the eigenvectors of the Schrodinger equation. As an alternative, one could give the author the benefit of the doubt. Why don't you respond to me as if I understand everyting you know, but not the answer to my question. PDBailey (talk) 15:05, 24 October 2008 (UTC)[reply]

I'm sorry, I tried. Your questions were "what is set intersection?", "what is probability?" and "what is a limit symbol?". These are fairly basic questions, that are hard for me to answer -- I cannot spend this much time trying to answer them. Since you imply you know some QM, but then ask these kinds of questions, I assumed you must be a student.

Even if you are not enrolled as a student, I'd like to remind that university libraries are still excellent resources for learning. Most any university library will have a broad selection of books on these topics. Most universities have programs that allow adults to get a library card, and peruse the stacks.

The topic of mixing does not involve either the Schroedinger equation, or complex conjugates in any way. The concept of eigenfunctions does peripherally impinge on the topic, but only peripherally, in that there are some theorems that are known, that relate mixing to the spectrum of an operator. However, spectra are more generally defined than they are in quantum mechanics; although QM does provide a good starting point for the more advanced topics, the proper setting is that of Hilbert spaces and Banach spaces. Again, I've really run out of time trying to rehash these topics; at this point, you will have to buckle down and do some hard studying to pick up the background knowledge for these various concepts. There is no magic wand that I can wave that will automatically enlighten you. linas (talk) 15:38, 24 October 2008 (UTC)[reply]

Linas, I think I understand your confusion more clearly now, but I hope you realize that a careful reading of each of those examples shows that I did not intend to ask any of those questions. In the first and third case, the question could be interpreted multiple ways (this is my fault) but I am asking you to give me the benefit of the doubt and believe me that I did not ask these questions. I am not suggesting that you do not know the meaning of the complex conjugate (that was my point), nor am I hiding my academic background (after all, it is on my user page--guess what, we share an alma mater). All I am asking is that you not talk down to me. PDBailey (talk) 16:13, 24 October 2008 (UTC)[reply]

Thank you very much for makingthese very informative edits, that is exactly what I was looking for. Unfortunately, I think we now have the same confusion. PDBailey (talk) 18:30, 24 October 2008 (UTC)[reply]

Wikipedia's Expert Peer Review process (or lack of such) for Science related articles[edit]

Hi - I posted the section with the same name on my talk page. Could you take part in discussion ? Thanks ARP Apovolot (talk) 14:08, 25 October 2008 (UTC)[reply]

oh please, mathworld is not a 'reference'[edit]

WOuld you please comment on this: Talk:Mahalanobis_distance#oh_please.2C_mathworld_is_not_a_.27reference.27 ? —Preceding unsigned comment added by Pot (talk • contribs) 21:18, 16 December 2008 (UTC)[reply]