(3) Use the recursive definition of "freeness" to justify the following (see examples in notes). You do NOT need to justify why particular subformulas actually are subformulas, so please don't confuse this with those kinds of problems from (4). (a) z occurs free in the formula ErvyP(x, y, z) (b) z occurs free in (V2VyP(x,y) → (Q(2) V R(a, b))) (c) y occurs free in V2(R(2) ↔r(¬P(x, y))) (d) y occurs free in (FrP(y) ^³y=z\r(Q(2,x) ✓ R(y,x)))

Fig: 1