Proceedings of the 13th ACM Conference on Electronic Commerce

The papers in these proceedings were presented at the 13th ACM Conference on Electronic Commerce (EC'12), held June 4-8 in Valencia, Spain. Since 1999 the ACM Special Interest Group on Electronic Commerce (SIGecom) has sponsored the leading scientific conference on advances in theory, systems, and applications for electronic commerce. The natural focus of the conference is on computer science issues, but the conference is interdisciplinary in nature, including research in economics and research related to (but not limited to) the following three non-exclusive focus areas: TF: Theory and Foundations (Computer Science Theory; Economic Theory) AI: Artificial Intelligence (AI, Agents, Machine Learning, Data Mining) EA: Experimental and Applications (Empirical Research, Experience with E-Commerce Applications) In addition to the main technical program, EC'12 featured four workshops and five tutorials. EC'12 was also co-located with the Autonomous Agents and Multiagent Systems (AAMAS) 2012 Conference. The call for papers attracted 219 submissions from authors in academia and industry all around the world --- a new record for the conference, and indeed a 16% increase over the previous record. Each paper was reviewed by at least three program committee members (all of whom were active researchers with PhDs) and two senior program committee members (who were all prominent, senior researchers) on the basis of scientific novelty, technical quality, and importance to the field. This matching was performed algorithmically, and offered the guarantee that there existed no blocking pairs of a reviewer who preferred a different paper and a paper that preferred a different reviewer. After extensive discussion and deliberation among the program committee, senior program committee and program chairs, 73 papers were selected for presentation at the conference. 57 of these are published in these proceedings. For the remaining 16, at the authors' request, only abstracts are included along with pointers to full working papers. This option accommodates the practices of fields outside of computer science in which conference publishing can preclude journal publishing. We expect that many of the papers in these proceedings will appear in a more polished and complete form in scientific journals in the future. For the first time, authors were allowed to explicitly align their papers with one or two of the conference's three focus areas, with the guarantee that they would be reviewed by SPC members and PC members aligned with the same area(s). Overall, the conference accepted submissions in every one of the six tracks induced by the three focus areas, with the TF, AI and EA tags being chosen by 147, 62 and 47 submissions and 50, 22 and 13 accepted papers respectively. (Note: because some papers chose two tags, these numbers sum to more than 219 and 73 respectively.) These tracks existed solely to provide a fair review process across different communities. To emphasize commonalities among the problems studied at EC, and to facilitate interchange at the conference, sessions were organized by topic rather than by focus area, and no indication of a paper's focus area(s) was given at the conference or appears in these proceedings. Also for the first time at EC, a third of the papers were presented in plenary sessions, with the other two thirds in parallel sessions. (Thus, attendees spent half their time in plenary sessions.) Quality was a necessary but not sufficient condition for getting a plenary slot; it was also necessary for reviewers to judge that a paper had broad appeal. Some of the conference's technically strongest work addressed smaller cross-sections of the community, and so appeared in parallel sessions. We had one overlap day with AAMAS, our co-located sister conference. We had a variety of joint activities: two invited talks (Colin Camerer and Moshe Tennenholtz), common coffee breaks, and two shared poster sessions (featuring EC papers, AAMAS papers, and EC-relevant papers published in the broader community over the last year). The latter poster session was another innovation this year: we solicited posters for papers relevant to the EC community that had been published in other venues during the past year. We accepted 22 posters for this session, and also featured posters from all EC authors who wished to present their paper in this additional format.