ICTIR

Welcome to ACM ICTIR 2021, the 7th conference with that name to be fully sponsored by the ACM Special Interest Group on Information Retrieval (SIGIR), and the 11th International Conference on the Theory of Information Retrieval. ICTIR is the premier forum for presenting and discussing research on theoretical and foundational aspects of Information Retrieval.

ICTIR 2021 is held online due to the COVID-19 pandemic, jointly with the 44th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2021). We would like to express our sincere gratitude to the SIGIR organizing committee for providing organizational and administrative support for hosting the virtual event.

The call for papers attracted high quality contributions from all over the world. We received 69 paper submissions and accepted 35 (or 51%) of them. We note that the acceptance rate is not a quality indicator, as our submission pool consisted of high quality papers. For each paper, we assigned 3 PC members to provide first-level reviews, resulting in a total of 207 reviews. The final acceptance decisions were made by the PC co-chairs based on the reviews and comments during the discussion period. We express special thanks to the 52 Program Committee (PC) members and a number of additional reviewers for their timely contributions to paper selection. We also thank the committee of the best paper awards chaired by Krisztian Balog.

As a new trial for this year, we allow authors to submit papers of any number of pages between 2 and 9 in content plus unrestricted space for references. Thus, there is no longer a distinction between long and short papers, nor a need for condensing or enlarging medium-length ones. In the reviewing process, the reviewers assessed whether the contribution is appropriate for the given length. We sincerely hope this new streamlined process will preserve the variety of paper lengths and foster the exchange of ideas without creating an artificial distinction among them.