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Description: Introduce a consequent to both sides of a logical equivalence. (Contributed by NM, 3-Jan-1993) (Proof shortened by Wolf Lammen, 17-Sep-2013)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | imbi1i.1 | ⊢ ( 𝜑 ↔ 𝜓 ) | |
| Assertion | imbi1i | ⊢ ( ( 𝜑 → 𝜒 ) ↔ ( 𝜓 → 𝜒 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | imbi1i.1 | ⊢ ( 𝜑 ↔ 𝜓 ) | |
| 2 | imbi1 | ⊢ ( ( 𝜑 ↔ 𝜓 ) → ( ( 𝜑 → 𝜒 ) ↔ ( 𝜓 → 𝜒 ) ) ) | |
| 3 | 1 2 | ax-mp | ⊢ ( ( 𝜑 → 𝜒 ) ↔ ( 𝜓 → 𝜒 ) ) |