On regular trace languages
Let A be a finite alphabet and let r be a symmetrical relation on A. Let us consider the free partially commutative monoid M(A,r) generated by A with respect to r (i.e., the quotient of A * by the congruence relation generated by (ab,ba) for all (a,b) in r). It is proved that the free partially commutative monoids M(A,r) whose regular sets form a Boolean algebra or are all unambiguous are the free products of free commutative monoids.
generalized automata on free products of monoids
scientific article; zbMATH DE number 4033115
scientific article