Rational relations and rational series
The paper deals with noncommutative rational series over an alphabet \(A\) with multiplicities in subsemirings of Rat \(B^*\). It is especially devoted to Fatou extension problems and usual decidability questions (equivalence, intersection, finiteness) concerning such series. It is proved in particular that the intersection problem is undecidable for rational series over the semiring of finite subsets of a one-letter alphabet.
scientific article; zbMATH DE number 64223
scientific article