domains
name=symbol
predicates
man(name)
woman(name)
parent(name,name)
husband(name,name)
c_brother(name,name)
c_sister(name,name)
husban(name,name)
wife(name,name)
clauses
man(alex).
man(alexandr).
man(sergey).
man(petr).
man(kostya).
man(mihail).
man(dmitriy).
man(valera).
man(nikolay).
woman(barbara).
woman(liza).
woman(lyuda).
woman(katya).
woman(anna).
woman(juli).
woman(raisa).
woman(tatiana).
parent(barbara,liza).
parent(anna,katya).
parent(anna,petr).
parent(sergey,katya).
parent(sergey,petr).
parent(tatiana,mihail).
parent(dmitriy,mihail).
parent(valera,nikolay).
parent(nikolay,raisa).
parent(raisa,kostya).
parent(liza,alex).
parent(alex,kostya).
parent(katya,juli).
parent(juli,lyuda).
parent(petr,alex).
parent(petr,alexandr).
parent(alexandr,lyuda).
parent(mihail,juli).
husband(sergey,anna).
husband(dmitriy,tatiana).
husband(mihail,katya).
husband(petr,liza).
husband(alexandr,juli).
husband(alex,raisa).
c_brother(X,Y):-parent(P,C1),parent(P,C2),
parent(C1,X),parent(C2,Y),
C1<>C2,man(X).
c_sister(X,Y):-parent(P,C1),parent(P,C2),
parent(C1,X),parent(C2,Y),
C1<>C2,woman(X),man(P).
husban(X,Y):-husband(X,Y),man(X).
wife(X,Y):-husband(Y,X),woman(X).
goal
%c_brother(X,Y).
% c_sister(X,Y).
husban(X,Y).
%wife(X,Y).