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visits member for 3 years, 8 months
seen Sep 15 at 15:04

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.
Aug
27
answered Algebraic process to find numbers so that $xy=45$ and $x+y=18$
Aug
27
comment Reference for understanding coalgebra
Majid's book "Foundations of quantum group theory" comes with an introduction to coalgebras and bialgebras. It's not very hard on the category theory.
Aug
27
comment Algebraic process to find numbers so that $xy=45$ and $x+y=18$
You need the pq-formula.
Jul
30
comment Why do we still do symbolic math?
One could go so far and say that there is no such thing as a "numerical solution", only a numerical approximation.
Jul
24
accepted Why are duals in a rigid/autonomous category unique up to unique isomorphism?
Jul
23
answered Why are duals in a rigid/autonomous category unique up to unique isomorphism?
Jul
22
awarded  Yearling
Jul
22
awarded  Excavator
Jul
22
comment Why are duals in a rigid/autonomous category unique up to unique isomorphism?
@ZhenLin, great, thanks! Do you want to make this into an answer? (If you don't have the time I can do that as well)
Jul
22
comment Why are duals in a rigid/autonomous category unique up to unique isomorphism?
Oh, maybe I understand what you're getting at: While $Y$ and $Y$ are the same objects, $(Y,\epsilon,\eta)$ and $(Y,e,h)$ are different duals. So the whole dual data is unique, but not the underlying object?
Jul
22
comment Why are duals in a rigid/autonomous category unique up to unique isomorphism?
@ZhenLin, what does "compatible with all that data" mean, other than "define the new $\epsilon$ and $\eta$ by composition" and "the new dual satisfies the snake identities"? As I see it now, my $(Y, e, h)$ is another dual and $f$ is a unique iso compatible with the data.
Jul
22
comment Why are duals in a rigid/autonomous category unique up to unique isomorphism?
@ZhenLin, yes, that's why I prove the snake identities for the new dualities. Or is there any more structure that the new duality must be compatible with?
Jul
22
asked Why are duals in a rigid/autonomous category unique up to unique isomorphism?
Jul
8
answered $[0, 1)$ and $S^1$ not homeomorphic?
Jul
2
awarded  Curious
Apr
21
comment Underlying functor of tensor product in a closed and symmetric monoidal category.
I wonder how many people have actually read this question completely. Can you shorten it somehow? (If necessary, restrict the audience to more experienced people by shortening)