Hyperdecidability of pseudovarieties of orthogroups
Let W denote the intersection with the pseudovariety of completely regular semigroups of the Mal'cev product of the pseudovariety of bands with a pseudovariety V of completely regular semigroups. It is shown that the (pseudo)word problem for W is reduced to that for V in such a way that decidability is preserved in the case in which terms involving only multiplication and weak inversion are considered. It is also shown that, if V is a hyperdecidable (respectively canonically reducible) pseudovariety of groups, then so is W.(Received April 29 1999)
1 The first author gratefully acknowledges support by FCT through the Centro de Matemática da Universidade do Porto, by the project Praxis/2/2.1/MAT/63/94, and by the Department of Mathematics of the University of Tasmania.