Lattices, Semigroups, and Universal Algebra [antikvár]

PREFACE This volume contains papers which, for the most part, are based on talks given at an international conference on Lattices, Semigroups, and Universal Algebra that was held in Lisbon, Portugál during the week of June 20-24, 1988. The conference was dedicated to the memory of Professor António Almeida Costa, a Portuguese mathematician who greatly contributed to the development of algebra in Portugál, on the 10th anniversary of his death. The themes of the conference reflect somé of his research interests and those of his students. The purpose of the conference was to gather leading experts in Lattices, Semigroups, and Universal Algebra and to promote a discussion of recent developments and trends in these areas. Ali three fields have grown rapidly during the last few decades with varying degrees of interaction. Lattice theory and Universal Algebra have historically evolved alongside with a large overlap between the groups of researchers in the two fields. More recent.ly, techniques and ideas of these theories have been used extensively in the theory of semigroups. Conversely, somé developments in that area may inspire further developments in Universal Algebra. On the other hand, techniques of semigroup theory have naturally been employed in the study of semilattices. Several papers in this volume elaborate on these interactions. The conference started with a public session during which J. Morgado addressed the historical significance of Almeida Costa's work on behalf of algebra in Portugál and H. J. Weinert discussed the recent developments connected with his research. The scientific program alsó included invited survey talks, contributed papers - somé which were alsó presented by invitation - and a problem session. The survey talks were given by J. Berman, M. Erné, R. Freese, G. Grátzer, P. Jones, G. Lallement, R. McKenzie, W. D. Munn, J. E. Pin, N. R. Reilly, J. Rhodes, J. Varlet, and H. Werner. The generál impression among the participants was that the conference met their expectations both scientifically and socially. The success of this conference depended on many people. Among them, the members of the scientific committee, J. Berman, J. A. Dias da Silva, Ph. Dwinger, J. Furtado Coelho, M. L. Galváo, G. Grátzer, J. Ilowie, G. Lallement, R. McFadden, J. Morgado, M. B. Ramalho, J. Varlet, and the members of the Universal Algebra and lattice theory group of the Centro de Algebra, in particular M. Sequeira, played a role in the preparation of the conference and of these Proceedings which is hereby acknowledged.