:-consult('/u/faculty/dick/cs320/prolog/family2.pl').
q:-halt.
%I married a widow who had a grown-up daughter.
male(me). female(widow). female(daughter).
parent(widow,daughter).
:-marry(me, widow).
% So I became the stepfather of her daughter.

%Some months later, my wife gave birth to a son.
:-birth(widow, me, son, son).

%My father, who visited us quite often, fell in love with my step-daughter,
%and married her.
male(father). parent(father, me).
:-marry(father, daughter).

%Hence, my father became my son-in-law, and my stepdaughter became my mother.

%The wife of my father, that is my step-daughter, also had a son.
birth(daughter, father, anotherson, son).

%My son became became my brother-in-law.
%of my father as well as my uncle.
%and I got a brother and at the same time a grandson. 
%My wife is my grandmother,
%since she is my mother's mother.
%Hence, I am my wife's husband and at the same time her step-grandson;
%in other words, I am my own grandfather.
?-grandfather(me, me).