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Mirrors > Home > MPE Home > Th. List > syl5bi | Structured version Visualization version GIF version |
Description: A mixed syllogism inference from a nested implication and a biconditional. Useful for substituting an embedded antecedent with a definition. (Contributed by NM, 12-Jan-1993.) |
Ref | Expression |
---|---|
syl5bi.1 | ⊢ (𝜑 ↔ 𝜓) |
syl5bi.2 | ⊢ (𝜒 → (𝜓 → 𝜃)) |
Ref | Expression |
---|---|
syl5bi | ⊢ (𝜒 → (𝜑 → 𝜃)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | syl5bi.1 | . . 3 ⊢ (𝜑 ↔ 𝜓) | |
2 | 1 | biimpi 219 | . 2 ⊢ (𝜑 → 𝜓) |
3 | syl5bi.2 | . 2 ⊢ (𝜒 → (𝜓 → 𝜃)) | |
4 | 2, 3 | syl5 34 | 1 ⊢ (𝜒 → (𝜑 → 𝜃)) |
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