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;;;  acquisition.lisp
;;;  Written by:  Shaul Markovitch
;;;  Last time modified: 10/1/2000
;;;
;;;
;;;  This files contains all the techniques used for acquisition
;;;  filtering.  These techniques decide whether to add a newly
;;;  generated macro to the macro database.  New techniques should be
;;;  defined and added to the list of possible techniques acording to
;;;  the example given here.
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(defclass acquisition-filter ()())


                     
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;;; acquisition-filter
;;;
;;; This is the genral function that is given a technique structure
;;; and applies the technique to filter out macros.
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;;; no-duplicate-acquisition-filter
;;;
;;; A very simple filter.  It tests whether the new macro is
;;; equivalent to any of the macros in the database.  Two macros are
;;; defined as equivalent if their start state and end state are equal
;;; Note that the states are compared using the predicate for
;;; comparing states given in the domain definition.
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(defclass no-duplicate (acquisition-filter) ())

(defmethod acquisition-filtering
  ((filter no-duplicate)
   macro macro-db domain &aux (eq-state (domain-state-equal-fn domain)))
  (not (member macro (macro-db-macros macro-db)
	       :test #'(lambda (m1 m2)
                           (and (funcall eq-state
                                         (macro-start-state m1)
                                         (macro-start-state m2))
                                (funcall eq-state
                                         (macro-end-state m1)
                                         (macro-end-state m2)))))
      ))