Manfred Droste is Professor and Head of the Automata and Formal Languages Research Group in the Department of Computer Science at the University of Leipzig. His research interests include such theoretical computer science topics as automata theory, logic, algebraic models for concurrent systems, and domain theory, and such mathematical topics as model theory, automorphism groups, and ordered algebraic structures. He is editor of the Handbook of Weighted Automata. László Fuchs is the Evelyn and John G. Phillips Distinguished Professor Emeritus in Mathematics at Tulane University. He was awarded the Kossuth Prize in 1953 and is a foreign member of the Hungarian Academy of Sciences. His research interests include abelian groups, commutative domains and their modules. He is the author of numerous publications, including Abelian Groups (Springer Monographs in Mathematics).  Brendan Goldsmith is Research Director at the School of Mathematical Sciences of the Dublin Institute of Technology. Formerly, he served as Head of the School of Mathematics and President of DIT. His research interests include group theory and generalizations, commutative algebra, associative rings and algebras, and mathematical logic. Lutz Strüngmann is Professor of Mathematics at the University of Duisberg-Essen. He has authored 56 publications since 1999 in the fields of group theory and generalizations, mathematical logic, commutative algebra and associative rings and algebras.