theorem receq1d (_G: wff) (_z1 _z2: nat) (S: set) (n: nat): $ _G -> _z1 = _z2 $ > $ _G -> rec _z1 S n = rec _z2 S n $;
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | hyp _h | _G -> _z1 = _z2  | 
        |
| 2 | eqsidd | _G -> S == S  | 
        |
| 3 | eqidd | _G -> n = n  | 
        |
| 4 | 1, 2, 3 | receqd | _G -> rec _z1 S n = rec _z2 S n  |