13,776 reputation
23185
bio website sci.ccny.cuny.edu/~benjamin
location New York City
age 41
visits member for 3 years, 1 month
seen 9 hours ago

I am an algebraist interested in a broad range of areas. I've worked on semigroups, geometric group theory, algebraic combinatorics, representation theory, self-similar groups (aka automaton groups), profinite groups and random walks on semigroups and groups. I've been particularly interested in interactions between these areas and Computer Science and am fond of algorithmic questions. I've also dabbled with operator algebras associated to etale groupoids and inverse semigroups. Currently, I am interested in applications of finite semigroup theory to finite state Markov chains.

My blog is http://bensteinberg.wordpress.com/author/bsteinbg/


1d
awarded  Nice Answer
1d
comment Examples of famous 'workhorse' theorems
Related mathoverflow.net/questions/99506/blackbox-theorems
Jul
18
answered a question about semigroups
Jul
18
comment a question about semigroups
Are you asking which semigroups have the property that the intersection of any two ideals is there product?
Jul
18
comment Reference for subsemigroups of $\mathbb{N}^n$
@LeeMosher, thanks.
Jul
15
comment Upper bound on cardinality of a field
This question might be better suited to mse.
Jul
14
answered Which algebraic theories have the property that $\mid$ is antisymmetric for all free algebras?
Jul
14
comment Which algebraic theories have the property that $\mid$ is antisymmetric for all free algebras?
In semigroup theory this preorder is called the $\mathcal J$-order. A semigroup is called $\mathcal J$-trivial if it is a partial order. There are a number of natural varieties of semigroups and monoids where all free algebras are J-trivial. Note J-triviality is given by finitely many quasiidentities. For finitary universal algebras you may need infinitely many.
Jul
14
comment Which algebraic theories have the property that $\mid$ is antisymmetric for all free algebras?
But the theory is the theory of monoids and semigroups. In your question you only ask about the relation on free objects.
Jul
14
comment Which algebraic theories have the property that $\mid$ is antisymmetric for all free algebras?
This relation is antisymmetric for monoids and semigroups without abelian and for many natural subvarieties.
Jul
13
comment Where can I find the classification of groups of order 16p?
@quid, I agree in general. But to repost the same question without saying so is inappropriate.
Jul
13
comment Where can I find the classification of groups of order 16p?
@quid, the op is in fact the OP of the migrated question as well.
Jul
13
comment Where can I find the classification of groups of order 16p?
@quid, the duplicate at mse was migrated from MO if that makes a difference.
Jul
13
comment On groups satisfying a law
Hanna Neumann's book Varieties of Groups is the classical reference.
Jul
12
comment Why are free groups residually finite?
This is essentially the same as the proof in my answer.
Jul
12
comment What recent programmes to alter highly-entrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail?
How goes the program to call a ring without identity a rng and a semiring (ring without negatives) a rng.
Jul
12
comment What recent programmes to alter highly-entrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail?
I do that sometimes.
Jul
12
awarded  Nice Answer
Jul
11
comment What recent programmes to alter highly-entrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail?
I think most group theorist use re and co-re.
Jul
11
answered What recent programmes to alter highly-entrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail?