Handling Ontology Gaps in Semantic Parsing

Andrea Bacciu, Marco Damonte, Marco Basaldella, Emilio Monti

Abstract
The majority of Neural Semantic Parsing (NSP) models are developed with the assumption that there are no concepts outside the ones such models can represent with their target symbols (closed-world assumption). This assumption leads to generate hallucinated outputs rather than admitting their lack of knowledge. Hallucinations can lead to wrong or potentially offensive responses to users. Hence, a mechanism to prevent this behavior is crucial to build trusted NSP-based Question Answering agents. To that end, we propose the Hallucination Simulation Framework (HSF), a general setting for stimulating and analyzing NSP model hallucinations. The framework can be applied to any NSP task with a closed-ontology. Using the proposed framework and KQA Pro as the benchmark dataset, we assess state-of-the-art techniques for hallucination detection. We then present a novel hallucination detection strategy that exploits the computational graph of the NSP model to detect the NSP hallucinations in the presence of ontology gaps, out-of-domain utterances, and to recognize NSP errors, improving the F1-Score respectively by ~21%, ~24% and ~1%. This is the first work in closed-ontology NSP that addresses the problem of recognizing ontology gaps. We release our code and checkpoints at https://github.com/amazon-science/handling-ontology-gaps-in-semantic-parsing.
Anthology ID:
2024.starsem-1.28
Volume:
Proceedings of the 13th Joint Conference on Lexical and Computational Semantics (*SEM 2024)
Month:
June
Year:
2024
Address:
Mexico City, Mexico
Editors:
Danushka Bollegala, Vered Shwartz
Venue:
*SEM
SIG:
SIGLEX
Publisher:
Association for Computational Linguistics
Note:
Pages:
345–359
Language:
URL:
https://aclanthology.org/2024.starsem-1.28
DOI:
Bibkey:
Cite (ACL):
Andrea Bacciu, Marco Damonte, Marco Basaldella, and Emilio Monti. 2024. Handling Ontology Gaps in Semantic Parsing. In Proceedings of the 13th Joint Conference on Lexical and Computational Semantics (*SEM 2024), pages 345–359, Mexico City, Mexico. Association for Computational Linguistics.
Cite (Informal):
Handling Ontology Gaps in Semantic Parsing (Bacciu et al., *SEM 2024)
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https://preview.aclanthology.org/jeptaln-2024-ingestion/2024.starsem-1.28.pdf
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