To understand the power of distributed systems, it is necessary to understand their inherent limitations: what problems cannot be solved in particular systems, or without sufficient resources (such as time or space). This book presents key techniques for proving such impossibility results and applies them to a variety of different problems in a variety of different system models. Insights gained from these results are highlighted, aspects of a problem that make it difficult are isolated, features of an architecture that make it inadequate for solving certain problems efficiently are identified, and different system models are compared.

DISC, the International Symposium on DIStributed Computing, is an annual conference for the presentation of research on the theory, design, analysis, implementation, andapplicationofdistributedsystemsandnetworks.DISC2003 was held on October 1-3, 2003 in Sorrento, Italy. There were 91 regular papers submitted to DISC this year. These were read and evaluated by the program committee members, assisted by external reviewers. The quality of submissions was high and we were unable to accept many deserving papers. Twenty-?ve papers were selected by the program c- mittee to be included in these proceedings. It is expected that these papers will be submitted, in a more polished form, to fully refereed scienti?c journals. TheBestStudentPaperAwardwasselectedfromamongtheacceptedpapers that were not co-authored by any program committee members. This year, the award was given to Ittai Abraham for the paper "Probabilistic Quorums for Dynamic Systems," co-authored with Dahlia Malkhi. The support of the University of Salerno, Italy and, in particular, its Dip- timento di Informatica ed Applicazioni is gratefully acknowledged. The review process and the preparation of this volume were done using CyberChair. I also thank Denise Lobo for her excellent help with these matters. October 2003 Faith Ellen Fich Organizing Committee Luigi Catuogno, University of Salerno, Italy Stelvio Cimato, University of Salerno, Italy Roberto De Prisco, University of Salerno, Italy and Akamai Technologies, USA (Chair) Barbara Masucci, University of Salerno, Italy DISC2003wassponsoredbytheUniversityof Salerno, Italy and, inparticular, itsDipartimentodiInformatica ed Applicazioni.

This book constitutes the refereed proceedings of the 15th Algorithms and Data Structures Symposium, WADS 2017, held in St. John's, NL, Canada, in July/August 2017. The 49 full papers presented together with 3 abstracts of invited talks were carefully reviewed and selected from 109 submissions. They present original research on the theory and application of algorithms and data structures in many areas, including combinatorics, computational geometry, databases, graphics, and parallel and distributed computing. The WADS Symposium, which alternates with the Scandinavian Symposium and Workshops on Algorithm Theory, SWAT, is intended as a forum for researchers in the area of design and analysis of algorithms and data structures. Papers presenting original research on the theory and application of algorithms and data structures