Ana Paula Escada; Jorge Almeida;
The globals of some
pseudovarieties of DA
Let R be the pseudovariety of all finite monoids whose principal right ideals have a unique generator, let \pv L be its dual, and let J=R \cap L. Using the word problem for free pro-J monoids, it is shown that the bilateral semidirect product Sl**J is local, where Sl denotes the pseudovariety of all finite semilattices. The global of the pseudovariety R\lor L is also computed and it is shown that this join is not local.
International Journal of Algebra and Computation