Figure 6: Collocational Constraints in Lexicon Entries
Figure 6 illustrates the familiar notion of collocational constraints. Again, the fact that the lexicon entry is grounded in the input allows a simple representation of collocations. In this case, the different realizations of LOCATION usually correspond to the semantic type of the object. Collocations can be used to override the default. The co-occurrence zone of the STOCK-MARKET entry simply states that if it is used as the range of a LOCATION relation, then the LOCATION relation should be introduced with ``on.'' This produces an English collocation such as ``the stock is sold on the stock market'' as opposed to the less natural ``... sold at the stock market.'' Notice that no additional work on collocations needs to be performed beyond the declarative knowledge encoding. The constraint-based control architecture will identify and assign preferences to collocations.