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Steven Sivek's user avatar
Steven Sivek's user avatar
Steven Sivek's user avatar
Steven Sivek
  • Member for 15 years, 2 months
  • Last seen more than a month ago
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Is it true that exotic smooth R^4 cannot be diffeomorphic to RxN, where N is a 3-manifold?
See Andy Putman's first comment on mathoverflow.net/questions/24970/… -- he cites McMillan for the fact that it has the standard PL structure, and then Munkres to show that this implies its smooth structure is standard.
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Making sure that you have comprehended a concept
@Mariano: see math.wayne.edu/~isaksen/Expository/carrying.pdf for "a cohomological viewpoint on elementary school arithmetic."
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"How not to write an NSF proposal" poster: does any one know where to find it online?
I don't know where to find the exact poster that was at MSRI, but there's a very similar one for astronomy: wia2009.gsfc.nasa.gov/contributed_posters/full_posters/…
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Who thought that the Alexander polynomial was the only knot invariant of its kind?
It's probably better to say Conway rediscovered the skein relation -- it's at the end of section 12 ("Miscellaneous theorems") of Alexander's original paper, but apparently nobody noticed this for decades.
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Algebraic topology beyond the basics: any texts bridging the gap?
The Kan seminar (18.915) at MIT does exactly this every fall -- see www-math.mit.edu/~mbehrens/18.915/index.html for two lists of suggested papers.
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What are your favorite instructional counterexamples?
And for p != q they can't be the fundamental group of a 3-manifold -- see mathoverflow.net/questions/6132/… for some references.
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