Logical Variables (II)

• Assume the following program:

  father_of(juan, pedro).
  father_of(juan, maria).
  father_of(pedro, miguel).
  mother_of(maria, david).
  grandfather_of(L,M):-
  father_of(L,N),
  father_of(N,M).
  grandfather_of(X,Y):-
  father_of(X,Z),
  mother_of(Z,Y).

• Answer the questions:

  1.

  ?- father_of(juan, pedro).

  2.

  ?- father_of(juan, david).

  3.

  ?- father_of(juan, X).

  4.

  ?- grandfather_of(X, miguel).

  5.

  ?- grandfather_of(X, Y).

  6.

  ?- X = Y, grandfather_of(X, Y).

  7.

  ?- grandfather_of(X, Y), X = Y.