Chapter 4, Metalinguistic Abstraction
Exercise 4.69
The interesting part of this exercise is that the first element in the conclusion of a rule which looked like a rule-name is just a member of the list to be matched against.
The code uses two rules find-son and find-grandson from in ex-4.63 and last-pair from in ex-4.62
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;;; Query input:
(assert! (rule ((grandson) ?g ?s) (find-grandson ?g ?s)))
Assertion added to data base.
;;; Query input:
(assert! (rule ((great . ?rel) ?gg ?s)
(and (find-son ?gg ?g)
(?rel ?g ?s)
(last-pair ?rel (grandson)))))
Assertion added to data base.
;;; Query input:
((great grandson) ?g ?ggs)
;;; Query results:
((great grandson) mehujael jubal)
((great grandson) irad lamech)
((great grandson) mehujael jabal)
((great grandson) enoch methushael)
((great grandson) cain mehujael)
((great grandson) adam irad)
;;; Query input:
(?relationship Adam Irad)
;;; Query results:
((great grandson) adam irad)
;;; Query input:
Output:
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;;; Query input:
((great grandson) ?g ?ggs)
;;; Query results:
((great grandson) mehujael jubal)
((great grandson) irad lamech)
((great grandson) mehujael jabal)
((great grandson) enoch methushael)
((great grandson) cain mehujael)
((great grandson) adam irad)
;;; Query input:
(?relationship Adam Irad)
;;; Query results:
((great grandson) adam irad)
;;; Query input: