Institute of Computer Science, University of Wroc
aw, ul. Przesmyckiego 20, Wroc
aw, 51-165, Polandf1
Abstract:
We show that the ** part of the equational theory modulo an AC symbol is undecidable. This solves the open problem 25 from the RTA list. We show that this result holds also for the equational theory modulo an ACI symbol.