52,506 reputation
16207468
bio website math.berkeley.edu/~qchu
location Berkeley, CA
age 25
visits member for 5 years, 10 months
seen 12 hours ago

I am a third-year graduate student at UC Berkeley. I'm interested in the interplay between homotopy theory, quantum field theory, manifold topology, and higher category theory.


1d
awarded  Necromancer
2d
awarded  Good Answer
Aug
28
comment Can any object in a presentable category be written as a colimit of generators?
@Mike: if you missed it, you can see more discussion of the point above at mathoverflow.net/questions/204792/…. I don't know an example off the top of my head; I haven't thought much about dense generators.
Aug
28
awarded  Favorite Question
Aug
26
comment Profinite groups, directed sets and $H^1$
$\prod_{i \in I} G_i$ is the cofiltered limit over $\prod_{i \in S} G_i$ as $S$ ranges over all finite subsets of $I$.
Aug
25
awarded  Necromancer
Aug
25
revised Does every manifold have a flat connection?
added 15 characters in body
Aug
25
answered Does every manifold have a flat connection?
Aug
24
comment On the Riesz representation theorem
I think Eric is asking whether you wanted some kind of uniformity with respect to $\psi$ in that limit. (It can be interpreted as a limit of functions of $\psi$ rather than just a limit of numbers.)
Aug
23
awarded  Nice Answer
Aug
21
awarded  Popular Question
Aug
21
comment Is there a geometric proof for the upper semicontinuity of fiber dimension in algebraic geometry?
Data point: at this point I've taken three courses called "algebraic geometry" and this theorem was never mentioned in any of them.
Aug
20
comment Categories of finite objects
Dualizability requires a monoidal structure to be well-defined, and with respect to either the product or the coproduct it's uninteresting (exercise). The OP explicitly gives the example of finite graphs, which dualizability doesn't capture. As I said in the comments, I think finiteness is a red herring here; the details of the OP's question seem to be about something else.
Aug
20
comment Crossed homomorphisms between power series groups
Crossposted: math.stackexchange.com/questions/1403457/…
Aug
19
comment Is an associative division algebra required for this phenomenon?
I think associativity is irrelevant. What you want is probably closer to en.wikipedia.org/wiki/Composition_algebra.
Aug
15
comment Does the fat geometric realization take limits to homotopy limits?
And: pullback squares that aren't homotopy pullback squares don't give you long exact sequences.
Aug
14
awarded  Nice Answer
Aug
14
awarded  Announcer
Aug
14
answered Does the fat geometric realization take limits to homotopy limits?
Aug
13
answered Torsion in the (co-)homology of a smooth projective variety - what is known in general?