User talk:Fropuff
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[edit] Group action
Nice edits on the group action page. Keep up the good work! - grubber 02:52, 5 October 2006 (UTC)
[edit] Your question at math help desk
You asked if a top group can be connected but not path connected. I'm a tad impulsive & i just put that stuff w/ a bit more as a question at sci.math.research w/ your handle Fropuff associated. hope u don't mind.Rich 08:21, 17 October 2006 (UTC)
- I don't mind at all. For anyone paying attention, Rich got an answer from Daniel Asimov on sci.math.research who pointed out that the solenoid is a connected topological group (even a compact abelian one) which is not path-connected. I believe the path-component of the identity is dense in this group but I'm not totally sure. -- Fropuff 18:40, 20 October 2006 (UTC)
[edit] Coarsest or finest?
I recently edited the disjoint union (topology) page to correct the definition, but that change was reverted so perhaps I should argue the case. The finest topology for which any given map is continuous is the discrete topology so the definition as currently stated is degenerate. We're interested in the smallest (or coarsest) topology for which the canonical injections are continuous. Tim
- No, the finest topology (or final topology) is the correct one. We are concerned with maps
where the Xi have a given topology. We are then trying to find a topology on the codomain X. If we stick the discrete topology on X then these maps may not be continuous. You increase the chances of continuity by coarsening the topology. They will certainly all be continuous when X has the trivial topology. So we go for the finest topology for which they are continuous. The coarsest topology (or initial topology) is used when you are trying to putting a topology on the domain of a family of functions rather than the codomain. -- Fropuff 16:55, 3 November 2006 (UTC)
[edit] Embedded submanifold
The article is indeed a special case for the Euclidean space. But when I wrote the article, there was no "submanifold" article at all - so it's better something than nothing. Also, in physics applications this Euclidean case is often good enough. Your article Submanifold is oriented primarily to the mathematicians - should we put my "Euclidean case" as the example in your article, so the physicists would also be able to find their way through? Thanks, --Sagi Harel 17:25, 12 November 2006 (UTC)
- I agree that the Euclidean case is important. Certainly, mention of it should be made in the submanifold article. The present version of that article is a stub at best. The Euclidean case probably even deserves its own article — I'm just not sure what the best name would be. Any thoughts? -- Fropuff 01:08, 13 November 2006 (UTC)
[edit] criterion
Please. "This criterion is..." or "These criteria are...". Michael Hardy 04:44, 25 November 2006 (UTC)
[edit] Hi
Did you attend the colloquium at UT today? It was fantastic. linas 04:19, 28 November 2006 (UTC)
- Was it? Damn, too bad I missed it. Hopefully I can catch the GADGET seminar Mark is giving tomorrow. -- Fropuff 06:51, 28 November 2006 (UTC)
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- Hmm, well I was going to pass as it'll be mostly over my head, but maybe I'll come anyway. You'll introduce yourself, right? Uhh, you've noticed me in these before, the irregular stranger? linas 15:17, 28 November 2006 (UTC)
[edit] Maths portal
There are some comments at Wikipedia:Featured portal candidates/Portal:Mathematics that you might be pleased to read :-) Tompw 19:17, 3 December 2006 (UTC)
- Cool. I'm glad people are liking it. And kudos to you for so diligently maintaining the portal! I sort of slacked off after redesigning it last year. Let me know if you ever need help with anything. -- Fropuff 01:07, 4 December 2006 (UTC)
[edit] Polar coordinate system
Hi Fropuff. Thanks for the comments at Talk:Polar coordinate system. I will try to address those issues. However, I admit, I really don't know about Euclidean metrics or multi-variable calculus (I only just turned 16, single-variable calculus is my limit for now). Can you perhaps add information about that to the article? Thanks. —Mets501 (talk) 12:03, 22 December 2006 (UTC)
- I will see if I can find the time. No promises. It might be some fun stuff for you to learn however. None of it is overly difficult. Finding the correct integration measure (rdrdθ) comes from a simple calculation of the Jacobian of the coordinate transformation (x,y) → (r,θ). Unfortunately, our article on metric tensors isn't very good, but it at least shows you how to calculate the Euclidean metric in polar coordinates. -- Fropuff 18:17, 22 December 2006 (UTC)
[edit] Flat
Hi Fropuff. I ran into your User:Fropuff/Tasklist where I saw such redlinks as flat connection and flat vector bundle. Well, let me pile on. How about adding there the following: Flat cohomology, Flat cover, Flat form, Flat manifold, Flat section, Flat space theorem, Flatness theorem, all from Wikipedia:Missing science topics/Maths10. Some of them are probably not related to geometry, but perhaps a few are. I don't mean you need to write all of them of course, but having some redlinks on a to-do list can work miracles in the long term. :)
You can reply here if you have comments. Cheers, Oleg Alexandrov (talk) 05:07, 30 January 2007 (UTC)
- Cool, more articles I don't have time to write :) But yes, I should update my tasklist with some of the more important redlinks (now that you mention it, it's very surprising that flat manifold is red — I had no idea). BTW, thanks a bunch for updating the List of mathematical redlinks. I continue to find that list useful. -- Fropuff 05:29, 30 January 2007 (UTC)
[edit] Commutative diagrams howto?
Hi Fropuff. How do you convert your commutative diagrams from LaTeX to PNG? Geometry guy 20:05, 10 February 2007 (UTC)
- I use John Walker's textogif Perl script. I believe the script makes use of the Netpbm library for doing the graphics conversions. I usually set the variables:
$dpi = 100; $res = 0.25;
- I do this on Windows using cygwin and MiKTeX. Of course, it should all work fine under Linux. -- Fropuff 01:56, 11 February 2007 (UTC)
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- Thanks. I'll try it: I made a new bundle map article and it would be nice to decorate it with commutative diagrams. Geometry guy 02:04, 11 February 2007 (UTC)
- So I noticed; looks good. I'll be happy to throw together a few diagrams if you can't get it to work. Just let me know. -- Fropuff 02:08, 11 February 2007 (UTC)
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- Well, I won't be trying it for a day or two at least, and if the two obvious diagrams (analogous to the two in the vector bundles article) miraculously appear in the bundle map article, it will certainly save me some work :) Geometry guy 02:16, 11 February 2007 (UTC)
[edit] How to draw diagrams for category theory
I want to write a wikipedia article but I'm not sure how draw diagrams (pullbacks etc)? I was told that maybe you could help? A user suggested that I should use LaTex to draw the diagrams, but it seems a bit tedious. —The preceding unsigned comment was added by Bgst (talk • contribs) 00:54, 25 February 2007 (UTC).
- I find using LaTeX to do the diagrams to be the easiest solution. I would use a vector graphics program but I've never found one that has any sort of decent mathematical typesetting ability. Once you get it all set up it's actually quite easily to do in LaTeX. You'll have to pick a diagram package to use. I use Paul Taylor's. Another one is by François Borceux. If you browse through my contributions at wikicommons you can find examples of how to write the code using Taylor's package (I've included the source with most of these files).
- After you draw the diagram in LaTeX you'll need to convert it to a suitable format for Wikipedia such as SVG or PNG. I would convert to SVG but I'm not aware of a TeX to SVG converter. For instructions on how to convert to PNG see the post immediately prior to this one. I hope that helps. And welcome to Wikipedia! -- Fropuff 02:04, 25 February 2007 (UTC)
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- Thanks I will try it - Bgst 15:41, 26 February 2007 (UTC)
[edit] Interior product and transition functions
I'm glad I was able to blue one of your redlinks (on Interior Product) by a simple move, though the article still needs a lot of work!
Your new Clifford bundle article is great, but I have a question: why bring in transition functions? (Here and in algebra bundle.) The modern point of view is to equip the bundle with a fibrewise algebra structure. Then local trivializations are required to respect this extra structure (much like the local trivializations of a vector bundle) and are therefore transition functions are automatically algebra automorphisms (just as transition functions for vector bundles are automatically linear). Geometry guy 23:50, 28 February 2007 (UTC)
- No good reason. You are quite right though. I'll reword those articles to make more sense. And thanks for moving interior product—I'd been meaning to do that. Perhaps I'll get around to working on that article sometime soon. It's in somewhat sad shape right now. -- Fropuff 01:25, 1 March 2007 (UTC)
[edit] Frame bundles
Hi Fropuff, your revision of frame bundle is looking great so far! I have some minor suggestions: for instance there is ambiguity in the notation GL(E) (as opposed to GL(M)) because it could refer to the bundle of fibrewise automorphisms, but I am happy to wait until you roll out the revised version before editing in my suggestions. This article will be useful in for the connection (principal bundle) article. I might roll out a provisional version soon, even though it needs much more editing, because I think that you (and hopefully others) will be able to do a great job of improving and rewriting it. Geometry guy 21:14, 2 March 2007 (UTC)
- Good point, thanks! And I look forward to your connection on principal bundles article. -- Fropuff 21:18, 2 March 2007 (UTC)
[edit] Speed of light needs expert to straighten out conflict.
I was contacted by POM on this, but I'm the wrong person. A person who understands special relativity and understands the typical misconceptions is needed to talk lucidly and diplomatically to the editors in conflict. Can you or someone else you know is up to it take a look? Thanks!Rich 06:45, 20 March 2007 (UTC)
- This seems to have settled down a bit: the undiplomatic anonymous editor has a valid point in my opinion (you can't just state formulae without saying what the terms mean) but I think it can easily be resolved. Geometry guy 22:42, 21 March 2007 (UTC)
Sorry for the delayed reply. The dispute seems to be one over an interpretation of variables. In the end it amounts to whether or not you have a minus sign in the formula. I have no problem with how the article is worded right now. Actually, the article that really could use some work is velocity-addition formula which is completely devoid of any interpretation. You might try posting at Wikipedia talk:WikiProject Physics to see if any is interested in working on it. It wouldn't take much to clean it up. -- Fropuff 06:11, 22 March 2007 (UTC)
[edit] Connections
I would appreciate your comments on the state of affine connection, since you are one of the few people here (are there just me and you still left?) who knows about Cartan connections, and I intend to use the experience gained to revise Cartan connection. Geometry guy 22:42, 21 March 2007 (UTC)
- Comments at Talk:Affine connection. I'm sure there's a few other people poking around here with knowledge of such things. They probably just lack the time or desire to contribute. So for now it seems to be just us. -- Fropuff 05:51, 22 March 2007 (UTC)
