Prolog

PART IV - Family

Example #1: Family

parent[X,Y]:-father[X,Y].
parent[X,Y]:-mother[X,Y].
son[X,Y]:-parent[Y,X]*male[X].
father[phil,charlie].
mother[liz,charlie].
male[charlie].

Resolution Trace for Example #1:

son[X,Y]	parent[Y,X]	father[X,Y]	mother[X,Y]	male[X]
son[A,B]
	parent[B,A]
		father[B,A]
		B=phil,A=charlie
				male[charlie]
				TRUE
				>>_son[charlie,phil]
				male[charlie] (#2)
				FALSE
		father[B,A] (#2)
		FALSE
	parent[B,A] (#2)
			mother[B,A]
			B=liz,A=charlie
				male[charlie]
				TRUE
				>>_son[liz,phil]
				male[charlie] (#2)
				FALSE
			mother[B,A] (#2)
			FALSE
	parent[B,A] (#3)
	FALSE
son[A,B] (#2)
FALSE
<<_son[charlie,phil]
>>son[charlie,phil]
<<_son[liz,phil]
>>_son[liz,phil]

<Under Construction>

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