There is no complete axiom system for shuffle expressions
Mathematical Institute, University of Gdańsk,
ul. Wita Stwosza 57, 80-952 Gdańsk, Po land;
Accepted: March 1999
In this paper we show that neither the set of all valid equations between shuffle expressions nor the set of schemas of valid equations is recursively enumerable. Thus, neither of the sets can be recursively generated by any axiom system.
Mathematics Subject Classification: 68Q45
© EDP Sciences, 1999