Guiding Search in FOIL

Again, we are trying to learn set of rules for Target-predicate = GrandDaughter(x,y).
Let the Examples contain
GrandDaughter(Victor,Sharon), Father(Sharon, Bob), Father(Tom, Bob), Female(Sharon), father(Bob, Victor)
To select best specialization, FOIL considers ways to bind the variables. With 4 constants (Victor, Sharon, Tom, and Bob) and 2 variables (x,y) we have 4*4 = 16 possible bindings.
{x/Victor, y/Sharon} is the only positive example binding for the rule "GrandDaughter(x,y) ←". The other 15 are negative bindings.
At each step, each rule is evaluated based on the sets of positive and negative variable bindings. Which one do we pick?