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Mirrors > Home > MPE Home > Th. List > ax3 | Structured version Visualization version GIF version |
Description: Standard propositional axiom derived from Lukasiewicz axioms. (Contributed by NM, 22-Dec-2002.) (Proof modification is discouraged.) (New usage is discouraged.) |
Ref | Expression |
---|---|
ax3 | ⊢ ((¬ 𝜑 → ¬ 𝜓) → (𝜓 → 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | luklem2 1666 | . 2 ⊢ ((¬ 𝜑 → ¬ 𝜓) → (((¬ 𝜑 → 𝜑) → 𝜑) → (𝜓 → 𝜑))) | |
2 | luklem4 1668 | . 2 ⊢ ((((¬ 𝜑 → 𝜑) → 𝜑) → (𝜓 → 𝜑)) → (𝜓 → 𝜑)) | |
3 | 1, 2 | luklem1 1665 | 1 ⊢ ((¬ 𝜑 → ¬ 𝜓) → (𝜓 → 𝜑)) |
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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