On the Trace Product and some Families of Languages Closed under Partial Commutations.

Giovanna Guaiana Antonio Restivo Sergio Salemi On the Trace Product and some Families of Languages Closed under Partial Commutations. 61-79 2004 9 Journal of Automata, Languages and Combinatorics 1 db/journals/jalc/jalc9.html#GuaianaRS04