imp_intrors_fo_nfls的假设和公式无关形式(不可引用)
theorem _hyp_imp_intrors_fo_nfls {x: set} (G A B: wff x):
$ \nf x G $ >
$ \nf x A $ >
$ G \imp A \imp B $ >
$ G \imp A \imp \fo x B $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | imp_repsecond | (G \imp \fo x A \imp \fo x B) \imp (A \imp \fo x A) \imp G \imp A \imp \fo x B |
|
| 2 | hyp g | \nf x G |
|
| 3 | hyp h | G \imp A \imp B |
|
| 4 | 2, 3 | _hyp_imp_intro_fo | G \imp \fo x A \imp \fo x B |
| 5 | 1, 4 | ax_mp | (A \imp \fo x A) \imp G \imp A \imp \fo x B |
| 6 | hyp n | \nf x A |
|
| 7 | 6 | fo_intro_nf | A \imp \fo x A |
| 8 | 5, 7 | ax_mp | G \imp A \imp \fo x B |