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Mirrors > Home > MPE Home > Th. List > eqeq12d | Structured version Visualization version GIF version |
Description: A useful inference for substituting definitions into an equality. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof shortened by Wolf Lammen, 23-Oct-2024.) |
Ref | Expression |
---|---|
eqeq12d.1 | ⊢ (𝜑 → 𝐴 = 𝐵) |
eqeq12d.2 | ⊢ (𝜑 → 𝐶 = 𝐷) |
Ref | Expression |
---|---|
eqeq12d | ⊢ (𝜑 → (𝐴 = 𝐶 ↔ 𝐵 = 𝐷)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqeq12d.1 | . . 3 ⊢ (𝜑 → 𝐴 = 𝐵) | |
2 | eqeq12d.2 | . . 3 ⊢ (𝜑 → 𝐶 = 𝐷) | |
3 | 1, 2 | eqeqan12d 2752 | . 2 ⊢ ((𝜑 ∧ 𝜑) → (𝐴 = 𝐶 ↔ 𝐵 = 𝐷)) |
4 | 3 | anidms 566 | 1 ⊢ (𝜑 → (𝐴 = 𝐶 ↔ 𝐵 = 𝐷)) |
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