Задача про нахождение родственников на генеологическом дереве

domains
 name=symbol
predicates
 grandfather(name,name)
 wifebrother(name,name)
 parent(name,name)
 plem(name,name)
clauses
 grandfather(henry,malik). 
 grandfather(henry,carol).
 grandfather(henry,paul).
 grandfather(henry,lydia).
 grandfather(adam,lydia).
 grandfather(adam,paul).
 grandfather(adam,william).
 grandfather(eriq,yulianna).
 grandfather(eriq,steven).
 grandfather(jack,yulianna).
 grandfather(jack,steven).
 grandfather(jack,christina).
 grandfather(john,yulianna).
 grandfather(john,mark).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 wifebrother(laura,james).
 wifebrother(sherry,sandy).
 wifebrother(mimi,megan).
 wifebrother(laura,megan).
 wifebrother(mimi,james).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 parent(henry,james).
 parent(henry,eriq).
 parent(henry,megan).
 parent(ira,james).
 parent(ira,eriq).
 parent(ira,megan).
 parent(adam,jack).
 parent(adam,delphi).
 parent(adam,sandy).
 parent(eve,jack).
 parent(eve,delphi).
 parent(eve,sandy).
 parent(mimi,malik).
 parent(eriq,malik).
 parent(eriq,carol).
 parent(laura,carol).
 parent(megan,paul).
 parent(jack,paul).
 parent(megan,lydia).
 parent(jack,lydia).
 parent(sherry,david).
 parent(jack,david).
 parent(sandy,william).
 parent(john,william).
 parent(malik,yulianna).
 parent(lydia,yulianna).
 parent(carol,steven).
 parent(david,steven).
 parent(david,christina).
 parent(gloria,christina).
 parent(gloria,george).
 parent(gloria,mark).
 parent(william,george).
 parent(william,mark).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 plem(carol,james).
 plem(lydia,james).
 plem(lydia,eriq).
 plem(yulianna,paul).
 
 goal  wifebrother(X,megan)or
           grandfather(Y,steven)or
           plem(yulianna,sherry).