4,592 reputation
11855
bio website math.berkeley.edu/~cgerig
location UC Berkeley
age 25
visits member for 3 years, 3 months
seen 6 hours ago

Undergrad: Allen Hatcher's recommendation got me accepted into Cornell (I learned Algebraic Topology through his book in high school, along with some email correspondences). But I majored in Engineering Physics, and did experimental research on gravity. Luckily, Ken Brown took me under his wing and provided weekly meetings to understand Group Cohomology.

Grad: I started my PhD in experimental atomic physics at Berkeley, but quit to do math. I am now a 2nd-year student of Michael Hutchings, wooo!


17h
revised Untwisting the Cohomology with Twisted Coefficients
added 37 characters in body
17h
awarded  Disciplined
Apr
14
comment Finite group acting on sphere
Subsequently, unless I'm thinking too quickly again, $\mathbb{Z}_3\times\mathbb{Z}_3$ acts similarly and provides the smallest odd-order counterexample to the question.
Apr
14
comment Finite group acting on sphere
Ah good catch. $\mathbb{Z}_2\times\mathbb{Z}_2$ acts on $S^2$ by rotation through two orthogonal axes (one per summand) with no fixed point, and the "4 poles" each have $\mathbb{Z}_2$-stabilizer.
Apr
14
comment Finite group acting on sphere
This is a small homework exercise in an Algebraic Topology class -- if a finite group $G$ acts freely on $S^{2n}$ then $G=\mathbb{Z}_2$ (using degree theory).
Apr
12
revised Shortest geodesic loop vs. shortest periodic geodesic
corrected name of my advisor :)
Apr
11
comment Genericity of maps which are transverse when restricted to a submanifold
Hirsch's Differential Topology, chapter II on transversality, Theorem 2.1(b)
Apr
10
reviewed Reject suggested edit on multiplication of two ergodic and stationary processes
Apr
5
accepted Extending Reeb field from contact submanifold to ambient contact manifold
Apr
5
revised Extending Reeb field from contact submanifold to ambient contact manifold
added 8 characters in body; edited title
Apr
2
revised Extending Reeb field from contact submanifold to ambient contact manifold
deleted 9 characters in body
Apr
2
asked Extending Reeb field from contact submanifold to ambient contact manifold
Mar
24
comment Ricci curvature under rough convergence
@AntonPetrunin, I spoke to John Lott, who remarked that there is an ambiguity in what the OP is after. The easy case is where the manifolds are of the same dimension. But his proof can handle the case where the limiting manifold has a different dimension (and for which he is unaware of an alternative proof).
Mar
19
reviewed Approve suggested edit on Largest order of automorphism group on a rooted tree?
Mar
12
awarded  Nice Question
Mar
11
reviewed Reject suggested edit on Irreducibility of reflexive compositions of polynomials (II)
Mar
4
answered Yang-Mills flow, Ricci flow and the holonomy
Mar
3
reviewed Approve suggested edit on What makes a theorem *a* “nullstellensatz.”
Feb
26
revised Integral formula for Euler class
edited body
Feb
10
reviewed Approve suggested edit on Skorohod theorem (weak convergence) on a discrete setting