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Metamath Proof Explorer
Description: Inference absorbing redundant antecedent. (Contributed by NM, 7-Nov-1995) (Proof shortened by Mel L. O'Cat, 28-Nov-2008)
|
|
Ref |
Expression |
|
Hypothesis |
pm2.43a.1 |
⊢ ( 𝜓 → ( 𝜑 → ( 𝜓 → 𝜒 ) ) ) |
|
Assertion |
pm2.43a |
⊢ ( 𝜓 → ( 𝜑 → 𝜒 ) ) |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
pm2.43a.1 |
⊢ ( 𝜓 → ( 𝜑 → ( 𝜓 → 𝜒 ) ) ) |
| 2 |
|
id |
⊢ ( 𝜓 → 𝜓 ) |
| 3 |
2 1
|
mpid |
⊢ ( 𝜓 → ( 𝜑 → 𝜒 ) ) |