(note TQG28)  ;; boolean version

;; contrary attribute case elimination

(instance Planet28-1 Class)
(subclass AstronomicalBody Object)
(subclass Planet28-1 AstronomicalBody)

(instance Rocky Attribute)
(instance Icy Attribute)
(instance Watery Attribute)
(instance Gaseous Attribute)
(contraryAttribute Rocky Icy Watery Gaseous)

(instance Object28-1 Planet28-1)

(attribute Object28-1 Watery)

(=>
  (and
    (contraryAttribute @ROW)
    (inList ?ATTR1 @ROW)
    (inList ?ATTR2 @ROW))
  (contraryAttribute ?ATTR1 ?ATTR2))

(=>
  (and
    (contraryAttribute ?ATTR1 ?ATTR2)
    (attribute ?O ?ATTR1))
  (not
    (attribute ?O ?ATTR2)))
    
(=>
  (contraryAttribute ?ATTR1 ?ATTR2)
  (contraryAttribute ?ATTR2 ?ATTR1))
          
(query (not (attribute Object28-1 Gaseous)))

(answer yes)


;; Fails, requires axiom for process of elimination on contraryAttribute(s)