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Mirrors > Home > MPE Home > Th. List > sylnibr | Structured version Visualization version GIF version |
Description: A mixed syllogism inference from an implication and a biconditional. Useful for substituting a consequent with a definition. (Contributed by Wolf Lammen, 16-Dec-2013.) |
Ref | Expression |
---|---|
sylnibr.1 | ⊢ (𝜑 → ¬ 𝜓) |
sylnibr.2 | ⊢ (𝜒 ↔ 𝜓) |
Ref | Expression |
---|---|
sylnibr | ⊢ (𝜑 → ¬ 𝜒) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sylnibr.1 | . 2 ⊢ (𝜑 → ¬ 𝜓) | |
2 | sylnibr.2 | . . 3 ⊢ (𝜒 ↔ 𝜓) | |
3 | 2 | bicomi 223 | . 2 ⊢ (𝜓 ↔ 𝜒) |
4 | 1, 3 | sylnib 327 | 1 ⊢ (𝜑 → ¬ 𝜒) |
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