theorem leid (a: nat): $ a <= a $;
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | addeq2 | x = 0 -> a + x = a + 0 |
|
2 | 1 | eqeq1d | x = 0 -> (a + x = a <-> a + 0 = a) |
3 | 2 | iexe | a + 0 = a -> E. x a + x = a |
4 | 3 | conv le | a + 0 = a -> a <= a |
5 | add0 | a + 0 = a |
|
6 | 4, 5 | ax_mp | a <= a |