theorem oddeqd (_G: wff) (_n1 _n2: nat): $ _G -> _n1 = _n2 $ > $ _G -> (odd _n1 <-> odd _n2) $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | hyp _nh | _G -> _n1 = _n2 |
|
| 2 | 1 | modeq1d | _G -> _n1 % 2 = _n2 % 2 |
| 3 | 2 | eqeq1d | _G -> (_n1 % 2 = 1 <-> _n2 % 2 = 1) |
| 4 | 3 | conv odd | _G -> (odd _n1 <-> odd _n2) |