Reduction relations for monoid semirings

AbstractIn this paper we study rewriting techniques for monoid semirings. Based on disjoint and non-disjoint representations of the elements of monoid semirings we define two different reduction relations. We prove that in both cases the reduction relation describes the congruence that is induced by the underlying set of equations, and we study the termination and confluence properties of the reduction relations

Languages recognized by a class of finite automata

We consider automata defined by left multiplications in graph algebras, and describe all languages recognized by these automata in terms of combinatorial properties of words which belong to these languages, regular expressions and linear grammars defining these languages. This description is applied to investigate closure properties of the obtained family of languages

Languages recognized by two-sided automata of graphs

We introduce two-sided automata defined by directed graphs and describe all languages recognized by these automata.C