nlp.logic

; Adapted from John DeNero's NLP lecture from Python to Logic
; Run at logic.cs61a.org

; Helpers
(fact (append () ?lst ?lst))
(fact (append (?f . ?r) ?x (?f . ?s))
      (append ?r ?x ?s))

; Types of Leaves
(fact (leaf N))
(fact (leaf V))
(fact (leaf J))

; Types of Non-Leaves
(fact (phrase NP))
(fact (phrase VP))
(fact (phrase S))

; Lexicon
(fact (N cows))
(fact (N buffalo))
(fact (N dogs))
(fact (V intimidate))
(fact (V buffalo))
(fact (J northern))
(fact (J buffalo))

; Grammar
(fact (S (NP . ?np) (VP . ?vp))
      (NP . ?np)
      (VP . ?vp))
(fact (NP (N ?n))
      (N ?n))
(fact (NP (J ?j) (N ?n))
      (J ?j)
      (N ?n))
(fact (VP (V ?v) (NP . ?np))
      (V ?v)
      (NP . ?np))

; Parse leaves
(fact (parse-piece (?word) (?type ?word))
      (leaf ?type)
      (?type ?word))

; Parse one-item phrases
(fact (parse-piece ?words (?type ?clause))
      (phrase ?type)
      (?type ?clause)
      (parse-piece ?words ?clause))

; Parse two-item phrases
(fact (parse-piece ?words (?type ?clause1 ?clause2))
      (phrase ?type)
      (?type ?clause1 ?clause2)
      (parse-piece ?words1 ?clause1)
      (parse-piece ?words2 ?clause2)
      (append ?words1 ?words2 ?words))

; Parse sentences
(fact (parse ?words (S . ?clauses))
      (parse-piece ?words (S . ?clauses)))

; Example: Finds all* sentences and their structures
; * not quite all, since the Logic interpreter has a depth limit to its search
; (query (parse ?sentence ?structure))

; Example: Finds all structures for "buffalo buffalo buffalo buffalo"
; (query (parse (buffalo buffalo buffalo buffalo) ?structure))


(fact (all-buffalo buffalo))
(fact (all-buffalo buffalo . ?rest)
      (all-buffalo . ?rest))
; Example: Finds all sentences/structures that are just the word buffalo repeated
; (query (parse ?sentence ?structure)
;        (all-buffalo . ?sentence))