Pseudovariety joins involving J-trivial semigroups
Jorge Almeida, Assis Azevedo, Marc Zeitoun · Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) · 1999
J. Rhodes asked during the Chico conference in 1986 for the calculation of joins of semigroup pseudovarieties. This paper proves that the join J v H of the pseudovariety J of J-trivial semigroups and of any 2-strongly decidable pseudovariety V of completely regular semigroups is decidable. This problem was proposed by the first author for V=G, the pseudovariety of finite groups.