2,852 reputation
918
bio website math.vanderbilt.edu/~peters10
location Vanderbilt University
age
visits member for 3 years, 10 months
seen yesterday

Jan
31
comment The category of subfactors extending the category of groups?
You could define a ``morphism'' from $(N_1 \subset M_1)$ to $(N_2 \subset M_2)$ to be a group homomorphism from the normalizer group $\mathcal N_{M_1}(N_1) / \mathcal U(N_1)$ to $\mathcal N_{M_2}(N_2) / \mathcal U(N_2)$. But I don't think you'll get much insight from this perspective.
Jan
31
comment The category of subfactors extending the category of groups?
Are you taking specific actions or are you looking for something which holds for arbitrary actions?
Jan
31
comment The category of subfactors extending the category of groups?
How are you having $G$ and $G'$ act on $R$?
Dec
20
answered Do syndetic sets on amenable semigroups have positive upper density?
Nov
13
comment Sets $E$ in $\mathbb{Z}$ such that any $l^2$ function with support on $E$ comes from Fourier of a continuous function
One characterization of an amenable group $\Gamma$ is that $\| \lambda(f) \|_\infty = \| f \|_1$ for any non-negative valued function $f \in \ell^1\Gamma$. So no amenable groups will have such an infinite subset. Which then begs the question: What about non-amenable groups which do not contain a non-cyclic free group?
Oct
14
awarded  Constituent
Oct
14
awarded  Caucus
Sep
26
answered Relative amenability of subgroups
Sep
8
comment A non-hyperfinite type III factor from an action of the free group on the circle
I don't follow your logic in part (d), why does $a.x = \gamma^n.x$?
Sep
6
answered Infinite finitely generated non-amenable groups
Aug
9
comment Relative commutants of abelian von Neumann algebras
@Jiang: Yes, that's correct. This example is far from typical though.
Jul
28
comment Is the fundamental group of $II_{1}$ factors invariant under a relation?
@SébastienPalcoux: This is because if $u \in L(\mathbb F_\infty) \subset M * L(\mathbb F_\infty)$ is a unitary with trace $0$ then $M$ is in free position from $u M u^*$, hence $M * M \cong W^*( M, u M u^* ) \subset M * L(\mathbb F_\infty) \cong M$.
Jul
27
revised Is the fundamental group of $II_{1}$ factors invariant under a relation?
removed open problem tag.
Jul
27
answered Is the fundamental group of $II_{1}$ factors invariant under a relation?
Jul
2
awarded  Enlightened
Jul
2
awarded  Nice Answer
Jun
25
awarded  Revival
May
31
awarded  Yearling
May
28
answered Characterization of amenable actions
May
28
comment Characterization of amenable actions
@Martin: Thanks, I thought this was the case, but I wanted to make sure.