theorem zmul02 (a: nat): $ a *Z 0 = 0 $;
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqtr | a *Z 0 = 0 *Z a -> 0 *Z a = 0 -> a *Z 0 = 0 |
|
2 | zmulcom | a *Z 0 = 0 *Z a |
|
3 | 1, 2 | ax_mp | 0 *Z a = 0 -> a *Z 0 = 0 |
4 | zmul01 | 0 *Z a = 0 |
|
5 | 3, 4 | ax_mp | a *Z 0 = 0 |