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| Mirrors > Home > ILE Home > Th. List > eleq2s | GIF version | ||
| Description: Substitution of equal classes into a membership antecedent. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) | 
| Ref | Expression | 
|---|---|
| eleq2s.1 | ⊢ (𝐴 ∈ 𝐵 → 𝜑) | 
| eleq2s.2 | ⊢ 𝐶 = 𝐵 | 
| Ref | Expression | 
|---|---|
| eleq2s | ⊢ (𝐴 ∈ 𝐶 → 𝜑) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | eleq2s.2 | . . 3 ⊢ 𝐶 = 𝐵 | |
| 2 | 1 | eleq2i 2263 | . 2 ⊢ (𝐴 ∈ 𝐶 ↔ 𝐴 ∈ 𝐵) | 
| 3 | eleq2s.1 | . 2 ⊢ (𝐴 ∈ 𝐵 → 𝜑) | |
| 4 | 2, 3 | sylbi 121 | 1 ⊢ (𝐴 ∈ 𝐶 → 𝜑) | 
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