Type Definition

Typed features are hierarchies of symbols which are interpreted by the unifier. They are defined by using the function define-feature-type.

          


(DEFINE-FEATURE-TYPE <name> <children>)
-> Asserts that <children> are the immediate specializations of <name> in a
   type hierarchy.


Example:


(define-feature-type mood (finite non-finite))
;; finite and non-finite are specializations of the mood symbol.


(define-feature-type epistemic-modality (fact inference possible))
;; The symbols fact, inference and possible are specializations of the
;; epistemic-modality symbol
          
          

 

The function subsume tests if a symbol (or an object in general) is a specialization of another symbol.  

          


(SUBSUME <symbol> <specialization>)
-> T is <specialization> is a specialization of <symbol>
   NIL otherwise.


Example:  (subsume 'mood 'finite)
          -> T


(subsume 'epistemic-modality `must')
          -> T


(subsume 'finite 'mood)
          -> NIL
          
          

The function reset-typed-features resets the working space and deletes all feature type definitions from memory. It is recommended to call it before loading a new grammar to avoid any side effect from previously defined types.  

          


> (reset-typed-features)