====== Casey Donoven (Binghamton) ======

====== The Covering Number of a Semigroup ======

===== Abstract for the Combinatorics Seminar 2019 February 12 =====

A semigroup is a set with an associative operation. A subsemigroup is a subset which is a semigroup with the same operation. σ(S), the //covering number// of a semigroup S (with respect to subsemigroups), is the minimum number of proper subsemigroups whose union is S. I will give a complete description of the covering numbers of finite semigroups.


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