Complex information systems rely on robust and coherent representations. These representations and associated reasoning techniques constitute the modern discipline of formal ontology, a branch of philosophy now essential to artificial intelligence and its many associated fields, including bioinformatics, knowledge engineering, information retrieval, and the semantic web.
This publication presents the proceedings of FOIS 2025, the 15th edition of the Formal Ontology in Information Systems conference, held as a face-to-face event from 10 to12 September 2025 in Catania, Italy, and preceded by a virtual conference online on 4 and 5 September. The FOIS conference series explores both theory and application, promoting and disseminating interdisciplinary research and international collaboration at the intersection of philosophical ontology, linguistics, logic, cognitive science, and computer science. This volume of proceedings includes two scientific keynote speeches: Towards Agentic AI – Neuro-Symbolic Organization of Research Contributions with Knowledge Graphs and Large Language Models, by Sören Auer, and Bringing Humans into Ontologies, by Sabina Leonelli. A total of 66 full paper submissions were received for the conference, of which 20 were accepted following a thorough double-blind review process, representing an acceptance rate of 30%. These are grouped in 3 sections under the subject areas of foundational papers; applications and methods; and domain and core ontologies.
Providing an overview of current research and developments in formal ontology, the volume will be of interest to all those working in the field.
