Polynomial Time Uniform Word Problems

We have two polynomial time results for the uniform word problem for a quasivariety Q: (a) The uniform word problem for Q can be solved in polynomial time iff one can find a certain congruence on finite partial algebras in polynomial time. (b) Let Q* be the relational class determined by Q. If any universal Horn class between the universal closure S(Q*) and the weak embedding closure S(Q*) of Q* is finitely axiomatizable then the uniform word problem for Q is solvable in polynomial time. This covers Skolem’s 1920 solution to the uniform word problem for lattices and Evans’ 1953 applications of the weak embeddability property for finite partial V algebras. Mathematics Subject Classification: 03D40, 06B25, 08A50, 08C15, 68Q25.