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Mirrors > Home > MPE Home > Th. List > vtoclga | Structured version Visualization version GIF version |
Description: Implicit substitution of a class for a setvar variable. (Contributed by NM, 20-Aug-1995.) Avoid ax-10 2139 and ax-11 2156. (Revised by Gino Giotto, 20-Aug-2023.) |
Ref | Expression |
---|---|
vtoclga.1 | ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) |
vtoclga.2 | ⊢ (𝑥 ∈ 𝐵 → 𝜑) |
Ref | Expression |
---|---|
vtoclga | ⊢ (𝐴 ∈ 𝐵 → 𝜓) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eleq1 2826 | . . . 4 ⊢ (𝑥 = 𝐴 → (𝑥 ∈ 𝐵 ↔ 𝐴 ∈ 𝐵)) | |
2 | vtoclga.1 | . . . 4 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) | |
3 | 1, 2 | imbi12d 344 | . . 3 ⊢ (𝑥 = 𝐴 → ((𝑥 ∈ 𝐵 → 𝜑) ↔ (𝐴 ∈ 𝐵 → 𝜓))) |
4 | vtoclga.2 | . . 3 ⊢ (𝑥 ∈ 𝐵 → 𝜑) | |
5 | 3, 4 | vtoclg 3495 | . 2 ⊢ (𝐴 ∈ 𝐵 → (𝐴 ∈ 𝐵 → 𝜓)) |
6 | 5 | pm2.43i 52 | 1 ⊢ (𝐴 ∈ 𝐵 → 𝜓) |
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