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seen Jan 25 at 20:56

Jan
14
revised Are units in rigid (autonomous) categories some sort of natural transformation?
added 28 characters in body
Jan
13
revised Are units in rigid (autonomous) categories some sort of natural transformation?
added 5 characters in body
Jan
12
accepted Are units in rigid (autonomous) categories some sort of natural transformation?
Jan
12
asked Are units in rigid (autonomous) categories some sort of natural transformation?
Dec
9
accepted Is the restriction of the regular representation of a finite group always a multiple of the subgroup?
Dec
9
comment Is the restriction of the regular representation of a finite group always a multiple of the subgroup?
Nice! Is there a standard reference for that?
Dec
9
asked Is the restriction of the regular representation of a finite group always a multiple of the subgroup?
Dec
9
comment Semisimplicity of restriction: Representation theory
I don't think this is true in general. Take $\mathbb{Z}_3 \triangleleft S_3$ and restrict the 2-dimensional irreducible representation of $S_3$. It will be the direct sum of two 1-dimensional representations since $\mathbb{Z}_3$ is abelian.
Dec
5
comment What is a simple example of an unprovable statement?
Right, if you tell them that this is a simplification, it's ok. I don't think oversimplifying puts off people as long as one doesn't create the impression "This guy must think I'm too stupid to understand the actual matter.". On the other hand, I noticed just today that including 'all the details' can be very off-putting. The ideal simplification, I find, is one that gives the audience the feeling of having understood some essential bits, while creating an impression of how much details are missing.
Dec
5
comment What is a simple example of an unprovable statement?
@AsafKaragila, there is a considerable difference in explaining something to a layperson in such a way that they are satisfied and understand why we are doing it, and explaining it so that they understand it in the same rigor like us, or in your words, "correctly". The latter requires a maths degree. But the former is something I do on a regular basis to people without mathematical background, and I do quantum gravity and category theory. And it's not an 'inferior' or 'worse' way of explaining, it's just explaining less.
Oct
30
comment Is there an opposite Yoneda Lemma?
Thanks! Now that you say it, it seems obvious.
Oct
30
accepted Is there an opposite Yoneda Lemma?
Oct
30
comment Is there an opposite Yoneda Lemma?
Yes, sorry, just a typo.
Oct
30
revised Is there an opposite Yoneda Lemma?
typo
Oct
30
asked Is there an opposite Yoneda Lemma?
Oct
28
answered Is there a Stokes theorem for covariant derivatives?
Sep
9
comment Does the boundary of a handle decomposition obtain a handle decomposition?
Not sure if you count this as an answer, but here is an algorithm how to transform the surgery diagram into a Heegard diagram, from which you can read off the handle decomposition: mathoverflow.net/questions/109261/heegard-diagram/109307#109307
Sep
5
asked How to get a Kirby diagram of $S^1 \times M^3$ if $M^3$ is given by a surgery diagram?
Sep
5
answered Coherence in braided monoidal categories
Sep
5
comment Coherence in braided monoidal categories
@ZhenLin, according to ncatlab, Douglas is right, and it follows from the hexagon identities and the axioms of a monoidal category.