@article{eprints344,
          number = {4/5},
            note = {Mathematics Subject Classification:

    68Q55;
    68Q68;
    08B05},
         journal = {RAIRO - Theoretical Informatics and Applications},
       publisher = {Cambridge University Press},
          author = {Flavio Corradini and Rocco De Nicola and Anna Labella},
           title = {A finite axiomatization of nondeterministic regular expressions},
            year = {1999},
          volume = {33},
           pages = {447--466},
        keywords = {    Semantics;
    regular expressions;
    axiomatizations;
    bisimulation.},
        abstract = {An alternative (tree-based) semantics for a class of regular expressions is proposed that assigns a central r{\^o}le 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 +. },
             url = {http://eprints.imtlucca.it/344/}
}