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Mirrors > Home > MPE Home > Th. List > pm2.52 | Structured version Visualization version GIF version |
Description: Theorem *2.52 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 8-Oct-2012.) |
Ref | Expression |
---|---|
pm2.52 | ⊢ (¬ (𝜑 → 𝜓) → (¬ 𝜑 → ¬ 𝜓)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | conax1k 174 | 1 ⊢ (¬ (𝜑 → 𝜓) → (¬ 𝜑 → ¬ 𝜓)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem is referenced by: (None) |
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