theorem leasym (a b: nat): $ a <= b -> b <= a -> a = b $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | anl | a <= b /\ b <= a -> a <= b |
|
| 2 | anr | a <= b /\ b <= a -> b <= a |
|
| 3 | 1, 2 | leasymd | a <= b /\ b <= a -> a = b |
| 4 | 3 | exp | a <= b -> b <= a -> a = b |