This book is a token of appreciation for Professor Gregory E. Kersten (1949-2020), one of the most prominent and active researchers and scholars in the broadly perceived field of collective decisions, notably negotiations, the author of numerous influential papers, books, and edited volumes, a great scientist, mentor, and a loyal friend and colleague. This book contains some papers in the fields of group and collective decisions, voting, social choice, negotiations, and related topics, with examples of real applications. The authors are top researchers and scholars from all over the world whose life and academic career has been inspired and influenced by Professor Kersten.