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Metamath Proof Explorer
Description: Theorem *2.26 of WhiteheadRussell p. 104. See pm2.27 . (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 23-Nov-2012)
|
|
Ref |
Expression |
|
Assertion |
pm2.26 |
⊢ ( ¬ 𝜑 ∨ ( ( 𝜑 → 𝜓 ) → 𝜓 ) ) |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
pm2.27 |
⊢ ( 𝜑 → ( ( 𝜑 → 𝜓 ) → 𝜓 ) ) |
| 2 |
1
|
imori |
⊢ ( ¬ 𝜑 ∨ ( ( 𝜑 → 𝜓 ) → 𝜓 ) ) |