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 A new book: the representation theory of finite monoids
 The uniform word problem for finite semigroups
 The first order theory of two endomorphisms of a finite dimensional vector space is undecidable
 Equalizers of free monoid morphisms, supports of rational power series and a question of Pin
 Isomorphism of oriented matroids from a semigroup viewpoint
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Monthly Archives: August 2013
Equalizers of free monoid morphisms, supports of rational power series and a question of Pin
In this mathoverflow question, J.E. Pin asked if it is decidable whether the support of a rational power series in noncommuting variables is a regular language. I pointed out that the answer is no and will elaborate here because it … Continue reading
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Isomorphism of oriented matroids from a semigroup viewpoint
This is in some sense a sequel to this post. Basically, I want to show that the somewhat awkward, in my opinion, definition of isomorphism of oriented matroids found, for example, here can be interpreted as isomorphism of underlying unary … Continue reading