First, indefeasible information is kept separate from default information, and it's always preserved under unification. Finally, defaults on a more general type are overridden by conflicting defaults on a more specific type. YADU has these design features in order to enable the efficient representation of and reasoning with information about word meaning. Because of the way YADU handles defaults, it allows them to be fully integrated into the grammar, rather than allowing defaults only at the meta-level as part of an extended description language. However, the main emphasis of this work has been to encode generalisations about word meaning.
Word senses are often predictable.
These generalisations are subject to idiosyncratic exceptions and variable degrees of conventionalisation. I am now complementing this work with stochastic techniques for processing words, to produce a model of semantic ambiguity resolution which is both efficient and robust. This work is part of the DISP project, and is in collaboration with Claire Grover and Mirella Lapata . I have a particular expertise and interest in all forms of default reasoning. You can find papers on all these topics here .