An almost-confluent congruential language which is not ChurchRosser congruential
It is fairly easy to show that every regular set is an almost-confluent congruential language (ACCL), and it is known [3] that every regular set is a ChurchRosser congruential language (CRCL). Whether there exists an ACCL, which is not a CRCL, seems to remain an open question. In this note we present one such ACCL.
congruential language thue systems string-rewriting systems congruence