Function proto_vulcan::relation::minusfd

pub fn minusfd<U, E, G>(
    u: LTerm<U, E>, 
    v: LTerm<U, E>, 
    w: LTerm<U, E>
) -> InferredGoal<U, E, G> where
    U: User,
    E: Engine<U>,
    G: AnyGoal<U, E>,