bio  website  math.berkeley.edu/~qchu 

location  Berkeley, CA  
age  24  
visits  member for  5 years, 5 months 
seen  1 hour ago  
stats  profile views  59,046 
I am a thirdyear graduate student at UC Berkeley. I'm interested in the interplay between homotopy theory, quantum field theory, manifold topology, and higher category theory.
7h

comment 
Proof that no differentiable spacefilling curve exists
@Yemon: oog, yeah, I guess, but in that case I've got nothing intelligent to say. 
8h

comment 
Proof that no differentiable spacefilling curve exists
en.wikipedia.org/wiki/Sard%27s_theorem 
12h

comment 
Is there a higher, “orientalish” version of geometric realisation?
I don't understand the question. What do you want this construction to output? An $\infty$category? 
12h

revised 
Has any attempt been made to classify finite groupoids?
deleted 50 characters in body 
12h

comment 
Has any attempt been made to classify finite groupoids?
@David: hmm, you're right. My bad. 
13h

awarded  Necromancer 
1d

comment 
Simply connected Lie groups homeomorphic to R^n are solvable
The reason you need $V$ in this argument is to guarantee that $\mathfrak{k}$ integrates to something compact; the argument fails for $G = \widetilde{SL}_2(\mathbb{R})$ precisely because $\mathfrak{k}$ does not integrate to a compact subgroup of $G$ in that case. You'd like to argue starting from the fact that the Killing form on $\mathfrak{g}_{ss}$ is negative definite on $\mathfrak{k}$, but it doesn't follow that the Killing form on $\mathfrak{k}$ itself is negative definite. 
1d

comment 
Classifying spaces of topological groups whose underlying spaces are homotopy equivalent
$BG$ is fundamentally an object which only makes sense up to weak homotopy equivalence; asking questions like this means getting bogged down in the technicalities of spaces not having the homotopy type of a CW complex and there's just no reason to torture yourself like that. 
2d

answered  Simply connected Lie groups homeomorphic to R^n are solvable 
Mar 27 
answered  Has any attempt been made to classify finite groupoids? 
Mar 26 
comment 
When does the Borel construction have the homotopy type of a CWcomplex?
Presumably this depends on a choice of $EG$. What $EG$ are you choosing? 
Mar 26 
awarded  Nice Answer 
Mar 26 
awarded  Necromancer 
Mar 26 
revised 
UFD and fundamental group
deleted 13 characters in body 
Mar 26 
comment 
StiefelWhitney class of complex projective spaces
Crossposted: math.stackexchange.com/questions/1206867/… 
Mar 26 
answered  UFD and fundamental group 
Mar 25 
comment 
Moduli space of flat connections over a torus
It is not a manifold in general. Lots of stuff is known about these sorts of spaces; one keyword you can use is "character variety." 
Mar 25 
revised 
Generators of invariant polynomials of semisimple Lie algebra
added 287 characters in body 
Mar 25 
comment 
Moduli space of flat connections over a torus
What do you mean by "known"? The moduli space of flat $G$connections on a torus is the space $\{ (g, h) \in G^2 : gh = hg \}$ of commuting pairs of elements of $G$ ($g, h$ are given by monodromy around a pair of generators of $\pi_1$) modulo the action of $G$ given by simultaneous conjugation. What does it mean to know this space? 
Mar 25 
answered  What is an infinite prime in algebraic topology? 