The positive integers form one of these constructs under   multiplication, and these constructs are equivalent to semigroups endowed with an identity.
The trace type of these entities is used as a model for concurrent computa- tion, and the history type of these entities arises in the same  eld. Semiautomata are associated with one of these entities called their characteristic or transition type. For a formal language L, the syntactic one of these objects is the smallest that recognizes L. The Kleene star is used to de ne the construction of the free type of these entities. The positive integers form one of these constructs under   multiplication, and these constructs are equivalent to semigroups endowed with an identity. For ten points, identify this mathematical structure with an associative binary operation and identity element.
The trace type of these entities is used as a model for concurrent computa- tion, and the history type of these entities arises in the same  eld.
monoids