%X We define the class of the linear systems whose solution is expressible as a tuple of nondeterministic regular expressions when they are interpreted as trees of actions rather than as sets of sequences. We precisely characterize those systems that have a regular expression as "canonical" solution, and show that any regular expression can be obtained as a canonical solution of a system of the defined class.
%I Elsevier
%P 179-189
%T Nondeterministic regular expressions as solutions of equational systems
%V 302
%N 1-3
%L eprints319
%A Rocco De Nicola
%A Anna Labella
%J Theoretical Computer Science
%D 2003
%R 10.1016/S0304-3975(02)00774-0