Laszlo Fuchs is an Evelyn and John G. Phillips Distinguished Professor of Mathematics at Tulane University, New Orleans, Louisiana. He is the author of more than 160 research papers on abelian groups, modules, and partially ordered algebraic systems and the author or coauthor of several books and lecture notes including the standard reference, Infinite Abelian Groups, Volumes /-// and, with Luigi Salce, Modules Over Valuation Domains (Marcel Dekker, Inc.). He has been a Professor at Eotvos University, Budapest, Hungary, and a Visiting Professor at universities in Australia, Canada, France, Germany, Israel, Italy, South Africa, and the United States. Rudiger Gobel is a Professor of Mathematics at the University of Essen, Germany. He is the author or coauthor of more than 100 research papers dealing with various aspects of abelian group theory and interactions between algebra and logic and the editor of several conference proceedings on abelian groups. He has been a Visiting Professor at universities in the United Kingdom, Germany, Israel, Ireland, Italy, and the United States.