The success of DSMs in essentially word-based tasks such as thesaurus extraction and construction (Grefenstette 1994;Curran 2004) invites an investigation into how DSMs can be applied to NLP and information retrieval (IR) tasks revolving around larger units of text, using semantic representations for phrases, sentences, or documents, constructed from lemma vectors.
the problem of compositionality in DSMs-of how to go from word to sentence and beyond-has proved to be non-trivial.