WORD2VEC NOT DEAD: PREDICTING HYPERNYMS OF CO-HYPONYMS IS BETTER THAN READING DEFINITIONS

Abstract

Expert-built lexical resources are known to provide information of good quality for the cost of low coverage. This property limits their applicability in modern NLP applications. Building descriptions of lexical-semantic relations manually in sufficient volume requires a huge amount of qualified human labour. However, given some initial version of a taxonomy is already built, automatic or semi-automatic taxonomy enrichment systems can greatly reduce the required efforts. We propose and experiment with two approaches to taxonomy enrichment, one utilizing information from word definitions and another from word usages, and also a combination of them. The first method retrieves co-hyponyms for the target word from distributional semantic models (word2vec) or language models (XLM-R), then looks for hypernyms of co-hyponyms in the taxonomy. The second method tries to extract hypernyms directly from Wiktionary definitions. The proposed methods were evaluated on the Dialogue-2020 shared task on taxonomy enrichment. We found that predicting hypernyms of cohyponyms achieves better results in this task. The combination of both methods improves results further and is among 3 best-performing systems for verbs. An important part of the work is detailed qualitative and error analysis of the proposed methods, which provide interesting observations of their behaviour and ideas for the future work.