Exercice 6.7 - Solution alternative

Woman ≡ Person ⊓ Female
Man ≡ Person ⊓ ¬Female

On veut démontrer
Person ⊑ Woman ⊔ Man

On suppose l'existence de b tel que 
Person(b)

Deux cas possibles: 

1) Female(b) 
Alors:
(Person ⊓ Female)(b)
Woman(b)

2) ¬Female(b)
Alors:
(Person ⊓ ¬Female)(b)
Man(b)

Donc, on soit Woman(b), soit Man(b), donc (Woman ⊔ Man)(b)