Marcelo Arenas is an Associate Professor in the Department of Computer Science at the Pontificia Universidad Catolica de Chile. He received his PhD from the University of Toronto in 2005. His research interests are in different aspects of database theory, such as expressive power of query languages, database semantics, inconsistency handling, database design, XML databases, data exchange, metadata management and database aspects of the Semantic Web. He has received an IBM PhD Fellowship (2004), seven best paper awards (PODS 2003, PODS 2005, ISWC 2006, ICDT 2010, ESWC 2011, PODS 2011 and WWW 2012) and an ACM-SIGMOD Dissertation Award Honorable Mention in 2006 for his PhD dissertation 'Design Principles for XML Data'. He has served on multiple program committees, and since 2009 he has been participating as an invited expert in the World Wide Web Consortium. Pablo Barcelo is an Assistant Professor in the Department of Computer Science at the University of Chile. He received his PhD from the University of Toronto in 2006. His main research interest is in the area of foundations of data management, in particular, query languages, data exchange, incomplete databases, and, recently, graph databases. He has served on program committees of some of the major conferences in database theory and the theoretical aspects of computer science (PODS, ICDT, CIKM, STACS, SIGMOD). Leonid Libkin is Professor of Foundations of Data Management in the School of Informatics at the University of Edinburgh. He was previously a Professor at the University of Toronto and a member of research staff at Bell Laboratories in Murray Hill. He received his PhD from the University of Pennsylvania in 1994. His main research interests are in the areas of data management and applications of logic in computer science. He has written four books and over 150 technical papers. He was the recipient of a Marie Curie Chair Award from the EU in 2006, and won four best paper awards. He has chaired programme committees of major database conferences (ACM PODS, ICDT) and was the conference chair of the 2010 Federated Logic Conference. He has given many invited conference talks and has served on multiple program committees and editorial boards. He is an ACM Fellow and a Fellow of the Royal Society of Edinburgh. Filip Murlak is an Assistant Professor in the Faculty of Mathematics, Informatics, and Mechanics at the University of Warsaw, Poland. Previously he was research fellow at the University of Edinburgh. He received his PhD from the University of Warsaw in 2008. His main research areas are automata theory and semi-structured data. He was the recipient of the best paper award at ICALP 2006, the Witold Lipski Prize for young researchers in 2008, and the Homing Plus scholarship from the Foundation for Polish Science in 2010. He was co-chair of MFCS 2011 and has served on program committees of several database and theoretical computer science conferences.