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Description: Deduce an equivalence from two implications. Variant of impbid . (Contributed by NM, 17-Feb-2007)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | impbida.1 | ⊢ ( ( 𝜑 ∧ 𝜓 ) → 𝜒 ) | |
| impbida.2 | ⊢ ( ( 𝜑 ∧ 𝜒 ) → 𝜓 ) | ||
| Assertion | impbida | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | impbida.1 | ⊢ ( ( 𝜑 ∧ 𝜓 ) → 𝜒 ) | |
| 2 | impbida.2 | ⊢ ( ( 𝜑 ∧ 𝜒 ) → 𝜓 ) | |
| 3 | 1 | ex | ⊢ ( 𝜑 → ( 𝜓 → 𝜒 ) ) |
| 4 | 2 | ex | ⊢ ( 𝜑 → ( 𝜒 → 𝜓 ) ) |
| 5 | 3 4 | impbid | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) |