Wednesday, 9th November 2022 - 11am - Hiba Arnaout : Seminar

Title:   Negative Statements Considered Useful

Abstract:

Machine knowledge about entities and their relationships has been a long-standing goal for AI researchers. Over the last 15 years, thousands of public knowledge bases (also known as knowledge graphs) have been automatically constructed from various web sources. They are crucial for use cases such as search engines. Yet, existing web-scale knowledge bases focus on collecting positive statements and store very little to no negatives. Due to their incompleteness, they operate under the open-world assumption. This means that the truth of absent information remains unknown, which compromises the usability of the knowledge base. In this talk, I make the case for the materialization of informative negation in large knowledge bases. I show why explicit negations are needed in open-world settings in use cases such as knowledge base completion and semantic search. I present how they can be automatically mined by locally inferring closed-world topics from reference comparable entities. I compare this approach with extractive (text-based) and generative (LM-based) methods, and finally discuss open issues and future opportunities.  

Bio:

Hiba Arnaout is a final-year PhD student at Max Planck Institute for Informatics in Saarbruecken, Germany, where she is a member of the Databases and Information Systems group, led by Gerhard Weikum. Her main interests include knowledge base search and curation, with a focus on negative knowledge in web-scale knowledge bases. Her work on negative knowledge received the best audience-choice paper award at AKBC, and was later selected as a significant Semantic Web-related research, presented at ISWC. Other aspects of this project were published at ISWC, VLDB, CIKM, and JWS. During her PhD, Arnaout spent time as a research visitor at The University of Edinburgh (2020) and Bosch Center for Artificial Intelligence (2021). She also presented tutorial sessions on her topic at VLDB, ISWC, KR, and WWW. Webpage: https://hibaarnaout.com

Add to your calendar

 vCal  iCal