%0 Journal Article
%A Corradini, Flavio
%A De Nicola, Rocco
%A Labella, Anna
%D 1999
%F eprints:344
%I Cambridge University Press
%J RAIRO - Theoretical Informatics and Applications
%K     Semantics;      regular expressions;      axiomatizations;      bisimulation.
%N 4/5
%P 447-466
%T A finite axiomatization of nondeterministic regular expressions
%U http://eprints.imtlucca.it/344/
%V 33
%X An alternative (tree-based) semantics for a class of regular expressions is proposed that assigns a central rôle to the + operator and thus to nondeterminism and nondeterministic choice. For the new semantics a consistent and complete axiomatization is obtained from the original axiomatization of regular expressions by Salomaa and by Kozen by dropping the idempotence law for + and the distribution law of • over +. 
%Z Mathematics Subject Classification:        68Q55;      68Q68;      08B05