The Lexicon and the Boundaries of Compositionality

Sentence-level creativity and word-level semantic creativity can actually be reconciled once we adopt a more sophisticated model of the lexicon. This type of solution is strongly pursued within the GL theory, in which enriching lexical representations with theory- constrained aspects of contextual knowledge is assumed to be the essential condition to turn compositional processes into real generative devices of meaning multiplicity. Although the idea of overcoming context-free lexical representations is surely a step forward with respect to more conservative views of word meaning, its actual implementation in GL still leaves many open issues. Representational devices like the qualia structure are important proposals for a more sophisticated architecture of the lexicon, but they need to be further explored and constrained before being able to reach a fully satisfactory explanatory power. The same holds true of the battery of extended semantic operations that are needed in GL to generate sense creativity in contexts. Promising theoretical prospectives are o®ered by distributional models of lexical representations. Notwistanding the many differences with GL, distributional models share with it some core assumptions. In particular, they push to its extreme consequences the idea itself of context-sensitive lexical representations. In distributional models, the re- lationship between lexical items and their context of use is somehow inverted, with the latter directly entering into the constitution of the former. According to this approach, it is not only sense-extensions to be generated in contexts, but lexical representations themselves, which emerge out of distribution of contexts of use. Assuming distributional semantic representations allows us to take into account the effect of polysemy in compositional processes, such as for instance the fact that polysemous items are associated with multiple similarity spaces whose shape and content can dramatically vary depending on the linguistic context of composition. Distributional models have become very popu- lar nowadays especially for natural language processing, given the possibilities they offer to bootstrap semantic representations directly from corpus data. However, they are not without problems. Actually, Lenci et al. (2005) provide a critical discussion of various types of of distributional models of meaning, which in many cases still have to prove their effective capacity to provide in-depth analyses of word meanings. Yet, notwithstanding their limits, these models represent an important probe to explore lexical dynamics. In particular, distributional models seem to suggest that the possibility for language to tolerate compositional processes side by side to sense creation processes is rooted in the fact that the boundaries between lexicon and context are much smoother and articulated than is often assumed. Distributional model of the lexicon are able to simulate the dynamics occurring between lexicon and context, and this way they can provide important insights on the interplay between lexical variation and sentence creativity, allowing us to further explore the boundaries of compositionality in natural language.