Preface It is our pleasure to bring you the proceedings of the 2010 Alberto Mendelzon Workshop on Foundations of Data Management (AMW 2010), the fourth in a series of workshops organized in memory of Alberto Mendelzon. The previous ones were held in Laguna San Rafael, Chile, November 2006 (http://grupoweb.upf.es/bd-web), Punta del Este, Uruguay, November 2007 (http://www.fing.edu.uy/inco/grupos/csi/AMW07), and Arequipa, Peru, May 2009 (http://db.cs.ualberta.ca/amw09). The workshop is an initiative of the Latin American data management research community, to which our friend, colleague and mentor Alberto so greatly contributed, and aims to create a periodical Latin America- based venue for high level research in the fundamental aspects of the area. This is a way to honor Alberto’s memory, and to enhance and solidify the research in the region. The call for papers resulted in the submission of 29 papers whose authors are from 16 countries around the world. All papers were thoroughly reviewed by the program committee. The program committee accepted 18 papers for presentation at the workshop, based on their technical merit and potential for stimulating discussions. The 18 accepted papers have been divided into six sessions: “Social Networks and Ontologies”, “RDF and XML Schemas”, “Constraints and Repairs”, “Query Processing and Rewriting”, “Access Control, Query Authentication, and Optimization” and “Multi-dimensional Matters.” In addition, the AMW 2010 technical program also includes keynote talks by Rakesh Agrawal from Microsoft Research, Ricardo Baeza-Yates from Yahoo! Research and Isabel Cruz from University of Illinois at Chicago, and tutorials by Gonzalo Navarro from Universidad de Chile, Renée Miller from University of Toronto and Val Tannen from University of Pennsylvania. We thank all the invited speakers for accepting our invitation and for their inspiring and informative talks and tutorials. The workshop would not have been possible without the support of many people. First of all we would like to thank Leopoldo Bertossi, Marcelo Arenas, Mariano Consens, Pablo Barceló, and Ricardo Baeza-Yattes, for their suggestions and insights in handling the paper submission and the reviewing process. We are very grateful to Alejandro Vaisman and his local organization team for their hard work. Finally, we would like to thank all the authors who contributed to the workshop and the program committee members for providing timely and thorough reviews, and also for actively participating during the paper discussion phase. We hope that you enjoy the AMW 2010 technical program, and also take the opportunity to explore the food, the wine, the music and many other attractions of this beautiful and cosmopolitan city that is Buenos Aires. Alberto H. F. Laender (Universidade Federal de Minas Gerais, Brasil) Laks V. S. Lakshmanan (University of British Columbia, Canada) Program Committee Co-Chairs