sicp-ex-4.57

one not using positive same:

  
  
  
 (rule (can-replace ?person1 ?person2) 
     (and (job ?person1 ?job1) 
          (or (job ?person2 ?job1) 
              (and (job ?person2 ?job2) 
                   (can-do-job ?job1 ?job2))) 
          (not (same ?person1 ?person2)))) 
 ; a 
 (can-replace ?x (Fect Cy D)) 
  
 ; b 
 (and (can-replace ?a ?b) 
      (salary ?a ?as) 
      (salary ?b ?bs) 
      (lisp-value < ?as ?bs))

meteorgan

  
  
 (a) (assert! (rule (replace ?person1 ?person2) 
                (and (job ?person1 ?job1) 
                     (job ?person2 ?job2) 
                     (or (same ?job1 ?job2) 
                         (can-do-job ?job1 ?job2)) 
                     (not (same ?person1 ?person2))))) 
 (b)  
 ;;; Query input: 
 (replace ?p (Fect Cy D)) 
  
 ;;; Query output: 
 (replace (Bitdiddle Ben) (Fect Cy D)) 
 (replace (Hacker Alyssa P) (Fect Cy D)) 
  
 (c)  
 (and (salary ?p1 ?a1) 
      (salary ?p2 ?a2) 
      (replace ?p1 ?p2)  
      (lisp-value > ?a2 ?a1)) 
 ;;; Query output: 
 (and (salary (Aull DeWitt) 25000) (salary (Warbucks Oliver) 150000) (replace (Aull DeWitt) (Warbucks Oliver)) (lisp-value > 150000 25000)) 
 (and (salary (Fect Cy D) 35000) (salary (Hacker Alyssa P) 40000) (replace (Fect Cy D) (Hacker Alyssa P)) (lisp-value > 40000 35000))