Operator Overview:

This operator performs lexical access on the current word (mediated by the phonological buffer ). This involves the following steps: 1) access the lexical entry for the word; 2) calculate the sister set if needed; 3) install the new word on the A/R set which includes projecting the new word to its X-bar and XP levels.

Operator Proposal:

When there is a word marked unaccessed on the auditory-input attribute of the top-space .

Operator Application:

Lexicon entries for the new word put profiles for the word on the ^sentence attribute. Syntactic and semantic profiles for the word are linked through a set of syn-sem-pointer productions. If there is more than one profile for the surface form of the word (i.e. polysemy) then a sister set is calculated. The attribute ^sister is for cases of polysemy. Thus, the profile for the noun meaning of GREEN is a ^sister of the profile for the adjective meaning of GREEN. The attribute ^sister will also point to a same-category sister, as in the case of the auxiliary verb HAVE and the main verb HAVE. The attribute ^same-sense-sister is for the projections of verbs: the V, I, and C profiles of a verb will all be linked through this pointer.

Once these attributes have been calculated, project-new-word productions fire to install the profiles on the zero-level of the appropriate category on the A/R set . These productions also create the X-bar and XP levels for each profile and fill in the ^head pointers, thereby completing the projections. They are then put on the one and max levels of the relevant category of the A/R set.

This applies for both syntactic and semantic lexical entries. One additional projection modifies the Semantics A/R set for predicate nominative constructions. This production allows the noun in the nominative position to assign an external role. This way it can become a property of its subject, thereby representing the semantics of the predicate nominative construction without any special purpose generate-operator proposals.

Operator Reconsider:

The access operator is reconsidered immediately as long as there is not more than two items on any level of the A/R set. This is checked through the presense of both the ^semantics-limit-met and the ^syntax-limit-met flags. If more than two items exist, an operator no-change occurs and the ar-set space is proposed, where the WM limit of two will be enforced by the remove operator.

Back to the operator hierarchy.

This page written by Julie Van Dyke (vandyke@cs.cmu.edu), August, 1997