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Mirrors > Home > ILE Home > Th. List > mth8 | GIF version |
Description: Theorem 8 of [Margaris] p. 60. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Josh Purinton, 29-Dec-2000.) |
Ref | Expression |
---|---|
mth8 | ⊢ (𝜑 → (¬ 𝜓 → ¬ (𝜑 → 𝜓))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm2.27 39 | . 2 ⊢ (𝜑 → ((𝜑 → 𝜓) → 𝜓)) | |
2 | 1 | con3d 593 | 1 ⊢ (𝜑 → (¬ 𝜓 → ¬ (𝜑 → 𝜓))) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-in1 576 ax-in2 577 |
This theorem is referenced by: (None) |
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