Learning First-Order Horn Clauses

Say we are trying to learn the concept Daughter(x,y) from examples.
Each person is described by the attributes: Name, Mother, Father, Male, Female.
Each example is a pair of instances, say a and b:
Name(a) = Sharon, Mother(a) = Louise, Father(a) = Bob, Male(a) = False, Female(a) = True
Name(b) = Bob, Mother(b) = Nora, Father(b) = Victor, Male(b) = True, Female(b) = False, Daughter(a,b) = True
If we give a bunch of these examples to CN2 or C4.5 they will output a set of rules like:
IF Father(a) = Bob ∧ Name(b) = Bob ∧ Female(a) THEN Daughter(a,b)
A first-order learner would output more general rules like
IF Father(x) = y ∧ Female(x) THEN Daughter(x,y)