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Metamath Proof Explorer
Description: Theorem *2.42 of WhiteheadRussell p. 106. (Contributed by NM, 3-Jan-2005)
|
|
Ref |
Expression |
|
Assertion |
pm2.42 |
⊢ ( ( ¬ 𝜑 ∨ ( 𝜑 → 𝜓 ) ) → ( 𝜑 → 𝜓 ) ) |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
pm2.21 |
⊢ ( ¬ 𝜑 → ( 𝜑 → 𝜓 ) ) |
| 2 |
|
id |
⊢ ( ( 𝜑 → 𝜓 ) → ( 𝜑 → 𝜓 ) ) |
| 3 |
1 2
|
jaoi |
⊢ ( ( ¬ 𝜑 ∨ ( 𝜑 → 𝜓 ) ) → ( 𝜑 → 𝜓 ) ) |