User talk:Igny

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Welcome!

Hello, and welcome to Wikipedia. Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! By the way, you can sign your name on Talk and vote pages using three tildes, like this: ~~~. Four tildes (~~~~) produces your name and the current date. If you have any questions, see the help pages, add a question to the village pump or ask me on my Talk page. Again, welcome!

Another good resource is Wikipedia:WikiProject Mathematics. Enjoy! Oleg Alexandrov 21:16, 20 Apr 2005 (UTC)

Contents

[edit] Thanks for your welcome

Hi Oleg, I am relatively new here, but will try to contribute as much as I can.

Relax, do no more than what is fun. :) Oleg Alexandrov 04:34, 21 Apr 2005 (UTC)

I see you are from Moldova... I am actually from Russia, currently at MSU.

Right. Actually I am ethnically Romanian, with poor Russian. Oleg Alexandrov 04:34, 21 Apr 2005 (UTC)

My twin's name is Oleg. So strange... Igny 03:34, 21 Apr 2005 (UTC)

Coincidences do happen. :) Oleg Alexandrov 04:34, 21 Apr 2005 (UTC)

[edit] Please vote on list of lists, a featured list candidate

Please vote at Wikipedia:Featured list candidates/List of lists of mathematical topics. Michael Hardy 20:29, 13 October 2005 (UTC)


[edit] Spasibo

Hello Igny, I just wanted to express my gratitude for your effort to normalize the conversation here. I’ve seen it before on that page and I really appreciate that. Thanks, Kober 19:58, 29 October 2006 (UTC)

[edit] Stalingrad documentary film

If you wish to see the two other parts of the documentary film you can find them here. http://video.google.com/videosearch?q=Stalingrad+osa The narrator speaks Finnish however, so I belive that the only thing you can understand are the interviews of Soviet veterans. Also, the documentary lasts nearly three hours, so you better reserve some time if you are planning to "take a look". Regards, --Kurt Leyman 05:42, 22 April 2007 (UTC)

[edit] Gagliardo--Nirenberg--Sobolev

Hi Igny. I would like your help if possible on the GNS inequality. I am onaraighl and I am the one who edited your article, but I am an applied mathematician and not an expert here.

It's just I have a problem with the GNS inequality if you don't subtract off a constant term: taking u=constant\neq0 on the open unit disc would satisfy the conditions of the theorem, yet gives constant\leq0, which seems to be a contradiction. I have spoken to some of my professors about the GNS inequality and consulted the functional analysis book by Kantorovich, and they all say that you need to subtract off the mean of the function in the GNS inequality.

I would dearly like it if it were the case that you did not have to subtract off the mean, since then some estimates that I am working on for the Cahn--Hilliard equation would work out a lot nicer, yet I just don't see how you can do that.

Also, perhaps the article would benefit from a discussion on the optimal constants for the bound, which clearly depends on the domain in question.

Thanks.

Hi again Igny. Thanks for reference - very useful. I can see where the compact support comes into the proof now. So the variant of the GNS you provide is restricted to functions that are C_1 on the whole of R^n, but with compact support. This limits one to a narrow class of functions indeed.

I have checked the literature and GNS applies to broader classes of functions:

  • C_1 functions with the norm of whose gradient is finite - see http://citeseer.ist.psu.edu/590313.html.
  • Functions defined on a compact, open domain of R^n with Lifshitz boundary. The function need not be C_1 on the whole of R^n then - it can be zero outside the domain in question. Then you have to subtract off the mean. See Kantorovich, p. 338.
  • Periodic functions on the n-torus. Then the mean is subtracted off. See Gibbon and Doering, appendix I. This latter case is a generalization of the Poincare inequality.

These variations also go by the name of GNS and maybe merit a discussion??

Thanks again for the reference, and for the article on wikipedia. I have fixed my estimates now :-)

[edit] Mathematics CotW

Hey Igny, I am writing you to let you know that the Mathematics Collaboration of the week(soon to "of the month") is getting an overhaul of sorts and I would encourage you to participate in whatever way you can, i.e. nominate an article, contribute to an article, or sign up to be part of the project. Any help would be greatly appreciated, thanks--Cronholm144 21:42, 13 May 2007 (UTC)

[edit] Digwuren is back!

I see that you have had an encounter with User:Digwuren at Allied occupation of Europe. He has been away for a week, but is now back at disrup doing constructive edits. The only solution to this "dispute" I can see is a community ban. -- Petri Krohn 21:37, 4 July 2007 (UTC)

[edit] Request for edit summary

Hi Igny. It could be nice if you could use the edit summary more often, especially for edits like this where it is not clear why you removed the link. Thanks. You can reply here if you have comments. Oleg Alexandrov (talk) 15:02, 11 July 2007 (UTC)

Hi Oleg, I am sorry for my laziness regarding the summaries and thank you for keeping an eye on the articles. The reason I deleted the link was that the Russian and English versions of Kolmogorov theorem were about different theorems by Kolmogorov. The Russian version actually refers to the Kolmogorov's result regarding Kolmogorov-Smirnov test rather that Hahn-Kolmogorov theorem (Igny 16:08, 11 July 2007 (UTC))
Cool. :) Thanks. Oleg Alexandrov (talk) 03:16, 12 July 2007 (UTC)

[edit] Kernel density

Hi Igny. I reverted this edit because I don't think it is correct, and because you did not explain why you made the change (please do that in the future). You can reply here if you have comments. Cheers, Oleg Alexandrov (talk) 16:17, 22 July 2007 (UTC)

Sigma was superfluous because there is parameter h. Regards, Igny.
Thanks, that makes sense. And again, it is good if you summarize what you changed, and especially, why you change something. That saves time and effort in the long run. Cheers, Oleg Alexandrov (talk) 03:42, 23 July 2007 (UTC)

[edit] Thank you for removing the list

Hi Igny. Just wanted to say thank you for removing the named fatality list from 2007_United_Kingdom_floods. Maintaining the thing was horrible, and not something I wanted to do anymore. If you need backup over the removal, please give me a shout: my talk page is the best place. Kind regards, Anameofmyveryown 01:55, 26 July 2007 (UTC)

[edit] Probability articles

Hi, Igny!

I notice that you've been doing quite a bit of rearranging of articles about probability, like Donsker's theorem and empirical process and Glivenko-Cantelli theorem, among others. That's good.

The difficulty I have is that sometimes your command of English idiom is not quite perfect. I know that has to be tough – especially with words like "the" (which has no equivalent in Russian). Anyway, I'm going to put some effort into making those articles read more smoothly, and I just want to give you a heads up before I get started in earnest.

I can see that you know the math extremely well (better than I do, no doubt). I just want to make the articles easier for native English speakers to read.

Thanks for all your good efforts! DavidCBryant 23:12, 9 August 2007 (UTC)

Thank you for correcting my English, I appreciate this. The thing is that I have all these math books lying around and all these lecture notes which I kept from my college, it is my dream to organize it all in accessible form and Wikipedia is perfect for that. I just wish I had more time for that. (Igny 00:37, 10 August 2007 (UTC))