Evgeny Kharlamov


2025

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GQC: LLM-Based Grouped QA Consolidation for Open-Domain Fact Verification at AVeriTeC
Dongzhuoran Zhou | Roxana Pop | Yuqicheng Zhu | Evgeny Kharlamov
Proceedings of the Eighth Fact Extraction and VERification Workshop (FEVER)

Structured fact verification benchmarks like AVeriTeC decompose claims into QA pairs to support fine-grained reasoning. However, current systems generate QA pairs independently for each evidence sentence, leading to redundancy, drift, and noise. We introduce a modular LLM-based QA consolidation module that jointly filters, clusters, and rewrites QA pairs at the claim level. Experiments show that this method improves evidence quality and veracity prediction accuracy. Our analysis also highlights the impact of model scale and alignment on downstream performance.

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Predicate-Conditional Conformalized Answer Sets for Knowledge Graph Embeddings
Yuqicheng Zhu | Daniel Hernández | Yuan He | Zifeng Ding | Bo Xiong | Evgeny Kharlamov | Steffen Staab
Findings of the Association for Computational Linguistics: ACL 2025

Uncertainty quantification in Knowledge Graph Embedding (KGE) methods is crucial for ensuring the reliability of downstream applications. A recent work applies conformal prediction to KGE methods, providing uncertainty estimates by generating a set of answers that is guaranteed to include the true answer with a predefined confidence level. However, existing methods provide probabilistic guarantees averaged over a reference set of queries and answers (marginal coverage guarantee). In high-stakes applications such as medical diagnosis, a stronger guarantee is often required: the predicted sets must provide consistent coverage per query (conditional coverage guarantee). We propose CondKGCP, a novel method that approximates predicate-conditional coverage guarantees while maintaining compact prediction sets. CondKGCP merges predicates with similar vector representations and augments calibration with rank information. We prove the theoretical guarantees and demonstrate empirical effectiveness of CondKGCP by comprehensive evaluations.

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Conformalized Answer Set Prediction for Knowledge Graph Embedding
Yuqicheng Zhu | Nico Potyka | Jiarong Pan | Bo Xiong | Yunjie He | Evgeny Kharlamov | Steffen Staab
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)

Knowledge graph embeddings (KGE) apply machine learning methods on knowledge graphs (KGs) to provide non-classical reasoning capabilities based on similarities and analogies. The learned KG embeddings are typically used to answer queries by ranking all potential answers, but rankings often lack a meaningful probabilistic interpretation - lower-ranked answers do not necessarily have a lower probability of being true. This limitation makes it difficult to quantify uncertainty of model’s predictions, posing challenges for the application of KGE methods in high-stakes domains like medicine. We address this issue by applying the theory of conformal prediction that allows generating answer sets, which contain the correct answer with probabilistic guarantees. We explain how conformal prediction can be used to generate such answer sets for link prediction tasks. Our empirical evaluation on four benchmark datasets using six representative KGE methods validates that the generated answer sets satisfy the probabilistic guarantees given by the theory of conformal prediction. We also demonstrate that the generated answer sets often have a sensible size and that the size adapts well with respect to the difficulty of the query.

2024

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Predictive Multiplicity of Knowledge Graph Embeddings in Link Prediction
Yuqicheng Zhu | Nico Potyka | Mojtaba Nayyeri | Bo Xiong | Yunjie He | Evgeny Kharlamov | Steffen Staab
Findings of the Association for Computational Linguistics: EMNLP 2024

Knowledge graph embedding (KGE) models are often used to predict missing links for knowledge graphs (KGs). However, multiple KG embeddings can perform almost equally well for link prediction yet give conflicting predictions for unseen queries. This phenomenon is termed predictive multiplicity in the literature. It poses substantial risks for KGE-based applications in high-stake domains but has been overlooked in KGE research. We define predictive multiplicity in link prediction, introduce evaluation metrics and measure predictive multiplicity for representative KGE methods on commonly used benchmark datasets. Our empirical study reveals significant predictive multiplicity in link prediction, with 8% to 39% testing queries exhibiting conflicting predictions. We address this issue by leveraging voting methods from social choice theory, significantly mitigating conflicts by 66% to 78% in our experiments.