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166151
bio website math.berkeley.edu/~ianagol
location Berkeley
age 45
visits member for 5 years, 9 months
seen 1 hour ago

I'm a professor at UC Berkeley working predominantly in the field of low-dimensional topology.


3h
comment Surgery along an arc connecting the components of a $2$-component link gives the unknot
I think this observation underlies the other papers I linked to.
3h
comment Surgery along an arc connecting the components of a $2$-component link gives the unknot
Hey Jim - the paper has nothing to do with Schoenfies - it's about 2-spheres embedded in $\mathbb{R}^4$ with 4 critical points. Saying such a sphere is standard is equivalent to saying that any band sum of the 2-component unlink which gives the unknot is standard. Scharlemann proves this actually for split links. A simpler proof was found later by Thompson. dx.doi.org/10.1016/0040-9383(87)90060-7
17h
revised Surgery along an arc connecting the components of a $2$-component link gives the unknot
added 368 characters in body
17h
answered Surgery along an arc connecting the components of a $2$-component link gives the unknot
2d
awarded  Nice Answer
2d
comment Is every nonabelian finite simple group a quotient of a triangle group $(a,b,c)$ with $a,b,c$ coprime?
I believe most finite simple groups are generated by elements of order 2 and 3, which addresses the 2nd part of your question. mathoverflow.net/a/59300/1345
2d
revised Intuition behind the Morse inequalities?
added 5 characters in body
Jul
27
answered Intuition behind the Morse inequalities?
Jul
21
comment Torsion in profinite groups
By intersect trivial, you mean intersect in the identity element? I don't see why this follows from point-set topology.
Jul
21
comment Torsion in profinite groups
Maybe you can expand the argument in your fourth sentence - I don't understand why one has only finitely many conjugates to intersect in the identity.
Jul
15
awarded  Enlightened
Jul
15
awarded  Nice Answer
Jul
15
comment the space of continuous maps between 3-manifolds
This was explained here: mathoverflow.net/a/19562/1345
Jul
9
answered Your favorite papers on geometric group theory
Jul
2
awarded  Nice Answer
Jul
1
comment PSL(2,p) as quotient of triangle groups
@ Will Sawin: maybe you could add more details of your "general nonsense" answer - this could be useful to people.
Jun
30
comment PSL(2,p) as quotient of triangle groups
Ok, well presumably you mean a scheme, in which case it's due to you-know-who.
Jun
30
comment PSL(2,p) as quotient of triangle groups
@ Will Sawin: Which "general nonsense" do you have in mind? Some model theory? And who originally made such arguments?
Jun
30
answered PSL(2,p) as quotient of triangle groups
Jun
23
comment Next steps on formal proof of classification of finite simple groups
How about a formalized proof of the existence of the Monster ;)