The Undecidability of the Semi-Unification Problem (Preliminary Report)

The Undecidability of the Semi-Unification Problem (Preliminary Report) A. J. Kfoury Jerzy Tiuryn Pawel Urzyczyn 468-476 conf/stoc/STOC22 1990 STOC db/conf/stoc/stoc90.html#KfouryTU90 http://doi.acm.org/10.1145/100216.100279