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Mirrors > Home > NFE Home > Th. List > pm2.45 | GIF version |
Description: Theorem *2.45 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.) |
Ref | Expression |
---|---|
pm2.45 | ⊢ (¬ (φ ∨ ψ) → ¬ φ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | orc 374 | . 2 ⊢ (φ → (φ ∨ ψ)) | |
2 | 1 | con3i 127 | 1 ⊢ (¬ (φ ∨ ψ) → ¬ φ) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∨ wo 357 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem depends on definitions: df-bi 177 df-or 359 |
This theorem is referenced by: pm2.47 388 dn1 932 eueq3 3011 |
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