Towards Evaluation of Cross-document Coreference Resolution Models Using Datasets with Diverse Annotation Schemes

TL;DR

This paper compares two cross-document coreference resolution datasets with different annotation schemes, introduces a new metric for lexical diversity, and discusses implications for model evaluation and generalizability.

Contribution

It provides a detailed analysis of dataset annotation schemes, proposes a new phrasing diversity metric, and suggests a combined evaluation approach for better model generalization.

Findings

NewsWCL50 has more lexically diverse coreference chains than ECB+.

Annotating NewsWCL50 results in lower inter-coder reliability.

Different datasets create distinct tasks for CDCR models, such as lexical disambiguation.

Abstract

Established cross-document coreference resolution (CDCR) datasets contain event-centric coreference chains of events and entities with identity relations. These datasets establish strict definitions of the coreference relations across related tests but typically ignore anaphora with more vague context-dependent loose coreference relations. In this paper, we qualitatively and quantitatively compare the annotation schemes of ECB+, a CDCR dataset with identity coreference relations, and NewsWCL50, a CDCR dataset with a mix of loose context-dependent and strict coreference relations. We propose a phrasing diversity metric (PD) that encounters for the diversity of full phrases unlike the previously proposed metrics and allows to evaluate lexical diversity of the CDCR datasets in a higher precision. The analysis shows that coreference chains of NewsWCL50 are more lexically diverse than those of ECB+ but annotating of NewsWCL50 leads to the lower inter-coder reliability. We discuss the different tasks that both CDCR datasets create for the CDCR models, i.e., lexical disambiguation and lexical diversity. Finally, to ensure generalizability of the CDCR models, we propose a direction for CDCR evaluation that combines CDCR datasets with multiple annotation schemes that focus of various properties of the coreference chains.