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Mirrors > Home > ILE Home > Th. List > bi2.04 | GIF version |
Description: Logical equivalence of commuted antecedents. Part of Theorem *4.87 of [WhiteheadRussell] p. 122. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
bi2.04 | ⊢ ((𝜑 → (𝜓 → 𝜒)) ↔ (𝜓 → (𝜑 → 𝜒))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm2.04 82 | . 2 ⊢ ((𝜑 → (𝜓 → 𝜒)) → (𝜓 → (𝜑 → 𝜒))) | |
2 | pm2.04 82 | . 2 ⊢ ((𝜓 → (𝜑 → 𝜒)) → (𝜑 → (𝜓 → 𝜒))) | |
3 | 1, 2 | impbii 126 | 1 ⊢ ((𝜑 → (𝜓 → 𝜒)) ↔ (𝜓 → (𝜑 → 𝜒))) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 105 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia2 107 ax-ia3 108 |
This theorem depends on definitions: df-bi 117 |
This theorem is referenced by: imim21b 253 pm4.87 557 imimorbdc 897 sbcom2v 1997 mor 2080 r19.21t 2565 reu8 2948 ra5 3066 unissb 3854 reusv3 4478 zfregfr 4591 tfi 4599 fun11 5302 prime 9381 raluz2 9608 isprm3 12149 isprm4 12150 bj-inf2vnlem2 15176 |
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