theorem rapp01 (a: nat): $ 0 @' a == 0 $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eq0al | 0 @' a == 0 <-> A. x ~x e. 0 @' a |
|
| 2 | elrapp | x e. 0 @' a <-> a, x e. 0 |
|
| 3 | el02 | ~a, x e. 0 |
|
| 4 | 2, 3 | mtbir | ~x e. 0 @' a |
| 5 | 4 | ax_gen | A. x ~x e. 0 @' a |
| 6 | 1, 5 | mpbir | 0 @' a == 0 |