Lexical substitution is the task of identifying a substitute for a word in the context of a clause. For instance, given the following text: "After the match, replace any remaining ﬂuid deﬁcit to prevent chronic dehydration throughout the tournament", a substitute of game might be given.
Lexical substitution is strictly related to word sense disambiguation (WSD), in that both aim to determine the meaning of a word. However, while WSD consists of automatically assigning the appropriate sense from a fixed sense inventory, lexical substitution does not impose any constraint on which substitute to choose as the best representative for the word in context. By not prescribing the inventory, lexical substitution overcomes the issue of the granularity of sense distinctions and provides a level playing field for automatic systems that automatically acquire word senses (a task referred to as Word Sense Induction).
In order to evaluate automatic systems on lexical substitution, a task was organized at the Semeval-2007 evaluation competition held in Prague in 2007. A Semeval-2010 task on cross-lingual lexical substitution has also taken place.
- D. McCarthy, R. Navigli. The English Lexical Substitution Task. Language Resources and Evaluation, 43(2), Springer, 2009, pp. 139–159.
- D. McCarthy, R. Navigli. SemEval-2007 Task 10: English Lexical Substitution Task. Proc. of Semeval-2007 Workshop (SEMEVAL), in the 45th Annual Meeting of the Association for Computational Linguistics (ACL 2007), Prague, Czech Republic, 23–24 June 2007, pp. 48–53.
- D. McCarthy. Lexical substitution as a task for WSD evaluation. In Proceedings of the ACL workshop on word sense disambiguation: Recent successes and future directions, Philadelphia, USA, 2002, pp. 109–115.
- R. Navigli. Word Sense Disambiguation: A Survey, ACM Computing Surveys, 41(2), 2009, pp. 1–69.