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Mirrors > Home > ILE Home > Th. List > sylnbi | GIF version |
Description: A mixed syllogism inference from a biconditional and an implication. Useful for substituting an antecedent with a definition. (Contributed by Wolf Lammen, 16-Dec-2013.) |
Ref | Expression |
---|---|
sylnbi.1 | ⊢ (𝜑 ↔ 𝜓) |
sylnbi.2 | ⊢ (¬ 𝜓 → 𝜒) |
Ref | Expression |
---|---|
sylnbi | ⊢ (¬ 𝜑 → 𝜒) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sylnbi.1 | . . 3 ⊢ (𝜑 ↔ 𝜓) | |
2 | 1 | notbii 668 | . 2 ⊢ (¬ 𝜑 ↔ ¬ 𝜓) |
3 | sylnbi.2 | . 2 ⊢ (¬ 𝜓 → 𝜒) | |
4 | 2, 3 | sylbi 121 | 1 ⊢ (¬ 𝜑 → 𝜒) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 105 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 |
This theorem depends on definitions: df-bi 117 |
This theorem is referenced by: sylnbir 679 mo2n 2054 reuun2 3418 regexmidlem1 4529 iotanul 5189 riotaund 5859 snnen2og 6853 |
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