bio  website  sci.ccny.cuny.edu/~benjamin 

location  New York City  
age  41  
visits  member for  3 years, 1 month 
seen  9 hours ago  
stats  profile views  6,973 
I am an algebraist interested in a broad range of areas. I've worked on semigroups, geometric group theory, algebraic combinatorics, representation theory, selfsimilar 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/blackboxtheorems 
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 
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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 Jtrivial. Note Jtriviality 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 
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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 
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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 
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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 
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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 
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On groups satisfying a law
Hanna Neumann's book Varieties of Groups is the classical reference. 
Jul 12 
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Why are free groups residually finite?
This is essentially the same as the proof in my answer. 
Jul 12 
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What recent programmes to alter highlyentrenched 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 
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What recent programmes to alter highlyentrenched 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 
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What recent programmes to alter highlyentrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail?
I think most group theorist use re and core. 
Jul 11 
answered  What recent programmes to alter highlyentrenched mathematical terminology have succeeded, and under what conditions do they tend to succeed or fail? 