Lexical items are marked as to the binary classes which they share. As demonstrated in {2)- these class-markings restrict the kinds of noun-verb-noun combinations that may appear within a clause. Such constraints are referred to as ‘selectional restrictions ’.

The assumption that lexical entries are organized in several hierarchies makes possible some simplifications of the representation of selectional restrictions. Consider these sentences:

In general it is the case that if a lexical item can be selected in a construction then everything dominated by that lexical item in the Be hierarchy (directly or indirectly) can also fit into that construction (e.g. the hierarchy firearm  that everything generically true of ‘firearm’ is specifically true of objects subordinate to ‘ firearm ’). Notice that if a binary feature solution were sought for the above cases, that corresponding to every level in the hierarchy which has a unique set of possible constructions, there would be a separate feature (e.g. ‘± shoots-bullets ’).¹

A similar simplification is achieved by use of the inalienable Have hierarchy.

That is, if an item in the Have hierarchy is a particular active construction then the items which dominate it in the Have hierarchy can also fit into that construction.²

¹ We are not claiming that there are no features which are pertinent to particular restricted sets of lexical items - in fact, if one argued that the feature ‘ ± shoots-bullets’ should be used, then our argument simply is that the feature + shoots bullets is predictable for everything below its first occurrence in the Be hierarchy. In other words, if other aspects of the formal treatment of the above problem require features for uniformity of notation, this can be accommodated easily. Nevertheless, it remains the case that the hierarchy can be utilized to reduce intuitively the duplication of lexical information.

² Note, however, that there is something odd about ‘the car mixes gas and air’, although it is technically correct. There are other cases like this: ‘the electric lamp has tungsten’, ‘the body has fingernails’. There are several potential explanations for the oddness of these sentences. (1) Certain words (e.g. carburator) are designated as referring to ‘the whole’ of an object and feature assimilation cannot pass through them. (2) We must distinguish between various senses of ‘have’; ‘have in it’; ‘have as part of it’; ‘have adjacent to it’. Then a car might be said to have a ‘ carburator ’ in it but not as part of it, while the ‘ venturi ’ is part of the carburator. It would not be the case that a car and a ‘ carburator’ ‘ have ’ a venturi in the same sense of,‘ have ’. (3) There might be a principle of linguistic performance: the more nodes an assimilation of features passes through, the lower the acceptability of the sentence.