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Mirrors > Home > MPE Home > Th. List > Mathboxes > frege30 | Structured version Visualization version GIF version |
Description: Commuted, closed form of con3d 155. Proposition 30 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.) |
Ref | Expression |
---|---|
frege30 | ⊢ ((𝜑 → (𝜓 → 𝜒)) → (𝜓 → (¬ 𝜒 → ¬ 𝜑))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frege29 40985 | . 2 ⊢ ((𝜓 → (𝜑 → 𝜒)) → (𝜓 → (¬ 𝜒 → ¬ 𝜑))) | |
2 | frege10 40974 | . 2 ⊢ (((𝜓 → (𝜑 → 𝜒)) → (𝜓 → (¬ 𝜒 → ¬ 𝜑))) → ((𝜑 → (𝜓 → 𝜒)) → (𝜓 → (¬ 𝜒 → ¬ 𝜑)))) | |
3 | 1, 2 | ax-mp 5 | 1 ⊢ ((𝜑 → (𝜓 → 𝜒)) → (𝜓 → (¬ 𝜒 → ¬ 𝜑))) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 |
This theorem was proved from axioms: ax-mp 5 ax-frege1 40944 ax-frege2 40945 ax-frege8 40963 ax-frege28 40984 |
This theorem is referenced by: frege59a 41031 frege59b 41058 frege59c 41076 |
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