theorem nfpr {x: nat} (a b: nat x): $ FN/ x a $ > $ FN/ x b $ > $ FN/ x a, b $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | anl | y = a /\ z = b -> y = a |
|
| 2 | anr | y = a /\ z = b -> z = b |
|
| 3 | 1, 2 | preqd | y = a /\ z = b -> y, z = a, b |
| 4 | hyp h1 | FN/ x a |
|
| 5 | hyp h2 | FN/ x b |
|
| 6 | 3, 4, 5 | nfnlem2 | FN/ x a, b |