For a string A = a1 . . . an, a reversal ρ(i, j), 1 ≤ i < j ≤ n, transforms the string A into a string A = a1 . . . ai−1ajaj−1 . . . aiaj+1 . . . an, that is, the reve...
In the maximum solution equation problem a collection of equations are given over some algebraic structure. The objective is to find an assignment to the variables in the equation...
This paper investigates the word problem for inverse monoids generated by a set Γ subject to relations of the form e = f, where e and f are both idempotents in the free inverse m...
Systems of language equations of the form {ϕ(X1, . . . , Xn) = ∅, ψ(X1, . . . , Xn) = ∅} are studied, where ϕ, ψ may contain set-theoretic operations and concatenation; the...
Due to extensive research on tree-width for undirected graphs and due to its many applications in various fields it has been a natural desire for many years to generalize the idea...