PROPER COVERS OF RESTRICTION SEMIGROUPS AND W-PRODUCTS
Mária B. Szendrei · International Journal of Algebra and Computation · 2011
Each factor semigroup of a free restriction (ample) semigroup over a congruence contained in the least cancellative congruence is proved to be embeddable into a W-product of a semilattice by a monoid. Consequently, it is established that each restriction semigroup has a proper (ample) cover embeddable into such a W-product.