bio  website  math.berkeley.edu/~ianagol 

location  Berkeley  
age  44  
visits  member for  4 years, 10 months 
seen  1 hour ago  
stats  profile views  11,237 
I'm a professor at UC Berkeley working predominantly in the field of lowdimensional topology.
2d

awarded  Nice Answer 
2d

comment 
When is the profinite completion a pro$p$ group?
@YiftachBarnea: do you have a nice example of a nontorsion finitely generated prop group which has finite abelianization (i.e. no map to $\mathbb{Z}_p$), and say which isn't powerful? I think Lazards result should rule out groups with powerful prop completion. 
Aug 26 
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When is the profinite completion a pro$p$ group?
The basilica group appears to have infinite abelianization. 
Aug 26 
comment 
When is the profinite completion a pro$p$ group?
Actually, I thought about this a bit more, and I don't see any way to guarantee that the RF quotient is nontorsion. 
Aug 26 
answered  When is the profinite completion a pro$p$ group? 
Aug 22 
comment 
How to find ICM talks?
I've made a version of my contribution to the ICM available here: math.berkeley.edu/sites/default/files/faculty/files/… 
Aug 21 
comment 
Heegaard genera of arithmetic 3manifolds
Yes, usually an arithmetic manifold is defined up to commensurability, so may include non congruence lattices. If Neil intended the meaning in GromovGuth, then he should probably clarify, since it is nonstandard. 
Aug 20 
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Heegaard genera of arithmetic 3manifolds
Their argument only applies to congruence arithmetic manifolds. 
Aug 20 
answered  Heegaard genera of arithmetic 3manifolds 
Aug 6 
comment 
Faithful representations of free prop groups
You might have a look at "Analytic prop groups": books.google.com/books?id=FjqngEACAAJ Since $F(p,m)$ is compact, the image must lie in a compact subgroup of $GL(n,F)$, which (up to finite index) is conjugate into $GL(n,\mathbb{O}_F)$. As shown in the book, such groups are "ppowerful", which in particular implies that they are analytic and not free. 
Jul 29 
revised 
Are there any very hard unknots?
added 14 characters in body 
Jul 27 
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Reference for the result that the systol map from Teichmuller space to curve complex is coarsely Lipschitz
This follows immediately from the main result (Theorem 1.1) of this paper, although I think it was known before by Minsky: link.springer.com/article/10.1007%2Fs000390070615x 
Jul 27 
answered  Properties of the Burnside kernel 
Jul 24 
comment 
BorelSerre compactification of $\mathbb{H}^3 / SL_2(\mathcal{O}_K)$
There's a minor correction: for $K=\mathbb{Q}[\sqrt{1}], \mathbb{Q}[\sqrt{3}]$, the cusp is actually an orbifold quotient of the elliptic curve by the group of units. 
Jul 22 
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Are there infinitely many commensurable classes of finitecovolume hyperbolic Coxeter groups?
@HaoCHEN: I see, yes, this is similar to the technique of GromovPiatetskiiShapiro I was alluding to. I wasn't aware of these examples (even though I downloaded a copy of Vinberg's paper :). 
Jul 22 
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Fake versus Exotic
The formula near the end of the paper looks reminiscent of a formula for geodesic torsion (but missing a $\cos(\phi_i)$ factor). Since the geodesic torsion of a curve of intersection of surfaces intersecting at constant angle is the same, I think this reproves your formula (maybe with a $\cos(\phi_i)$ factor or using $\sin(2\phi_i)$ instead)? encyclopediaofmath.org/index.php/Geodesic_torsion 
Jul 22 
awarded  Enlightened 
Jul 22 
awarded  Nice Answer 
Jul 20 
comment 
A question on involutions on the Lie algebra of vector fields
On odd dimensional spheres, the antipodal map works. 
Jul 20 
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A question on involutions on the Lie algebra of vector fields
What do you have in mind for the Killing form for the space of vector fields? 