%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% %R References . . . . . . . . . . . . . . . . . . . . . . . . . references %% %% The following are the references. They are ordered with respect to the %% last name of the first author. %% \begin{thebibliography}{20} \bibitem[Al]{Almeida:book} J. Almeida, \newblock {\it Finite Semigroups and Universal Algebra} \newblock World Scientific, ... \bibitem[Ash]{Ash} C. Ash, \newblock Inevitable graphs: a proof of the type II conjecture and some related decision procedures, \newblock Int. J. Algebra and Computation, 1 (1991) 127--146. \bibitem[Del:98]{Delgado:1998} M. Delgado, \newblock Abelian pointlikes of a monoid, \newblock Semigroup Forum {\bf 56} (1998) 339--361. \bibitem[Del]{commutative} M. Delgado, \newblock Commutative images of rational languages and the Abelian kernel of a monoid, \newblock preprint, CMUP 2001-03. \bibitem[DF]{Delgado&Fernandes:2000} M. Delgado and V. H. Fernandes, \newblock Abelian kernels of some monoids of injective partial transformations and an application, \newblock Semigroup Forum {\bf 61} (2000) 435--452. \end{thebibliography}