This volume contains the proceedings of the Twenty-sixth European Conference on Artificial Intelligence (ECAI 2023), held from September 30th to October 4th, 2023. Since 1974, the European Conference on Artificial Intelligence, organised by the European Association for Artificial Intelligence (EurAI), has been the premier venue for presenting AI research in Europe. ECAI is the place for researchers and practitioners of Artificial Intelligence (AI) to gather and to discuss the latest trends and challenges in all subfields of AI as well as to demonstrate innovative applications and uses of advanced AI technology. ECAI was originally organised as a biennial event, but is now a yearly event, co-organised with the International Joint Conference on Artificial Intelligence (IJCAI) every four years.

ECAI 2023 had a record number of submissions with 1896 paper submissions of which 1691 papers were retained for review. The selection process was competitive, with an acceptance rate of 24%. The largest number of submissions were in the broad areas of Machine Learning (28%), Natural Language Processing and Multi Agent Systems (each with 12%), Vision and Knowledge Representation and Reasoning (each with 8%).

ECAI 2023 coordinated with IJCAI 2023 to allow rejected papers from this conference to submit their original reviews together with a statement about how the paper was revised, and also allowed AAMAS 2023 extended abstracts to be submitted to the conference. We received 108 submissions, out of which 32 were accepted, resulting in a somewhat higher acceptance rate than regular submissions.

This ECAI edition included 5 keynote speakers: Emma Brunskill (Stanford), Ryan Cotterell (ETH), Gal Chechik (Bar Ilan), Ariel Procaccia (Harvard), Shannon Vallor (Edinburgh), and a contribution by Luc Steels on the occasion of his EurAI Distinguished Service Award 2022.

ECAI 2023 included 10 tutorials, selected by the Tutorial Chairs Jacek Mańdziuk and Bart Bogaerts, and 21 workshops, selected by the Workshop Chairs Tom Lenaerts and Paolo Turrini. Following tradition, ECAI 2023 incorporated the 12th Conference on Prestigious Applications of Intelligent Systems (PAIS 2023), chaired by Claudia Goldman and Martin Atzmueller. The 10 papers from PAIS are included in this volume.

ECAI 2023 had a special focus on starting researchers, who had the opportunity of participating in several specific events including the 10th Starting AI Researcher Symposium (STAIRS) chaired by Katrien Beuls and Malte Schilling, a Doctoral Consortium, chaired by Nadin Kokciyan and Piotr Skowron, and the traditional Meeting with an EurAI Fellow.

We would like to thank the authors, the Area Chairs (ACs), Senior Program Committee members (SPCs), and regular Program Committee members (PCs), for their work, which unfortunately spanned over the summer holidays.

We also want to thank all chairs who have done an excellent job in their selection tasks and have been very prompt and active and responsive for the entire period of the conference organisation. We are also indebted to over 1,000 of ECAI 2023 authors who volunteered to join a reviewing pool and be called to assist in reviewing a paper. This allowed us to recruit competent reviewers at short notice and to ensure the quality of the reviews.

We are particularly grateful to the workflow chairs Roxana Rădulescu and Roy Fairstein for providing us with essential help throughout our ECAI journey, from writing scripts to managing the review process, assisting with communication with the authors and chairs, and planning the conference program. We are also obliged to Tito Cruz who helped in the assignment of the papers to review, selecting accepted papers, and planning the technical sections. Without their help we would have been lost.

We are grateful for all the assistance from EurAI in providing us with resources, support and advice. Special thanks to Carles Sierra, EurAI Chair, for always being available to us and helping us with all of our requests.

Kobi Gal

ECAI 2023 Program Chair

Ann Nowé

ECAI 2023 General Chair