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Mirrors > Home > MPE Home > Th. List > cbvmptv | Structured version Visualization version GIF version |
Description: Rule to change the bound variable in a maps-to function, using implicit substitution. (Contributed by Mario Carneiro, 19-Feb-2013.) Add disjoint variable condition to avoid auxiliary axioms . See cbvmptvg 5185 for a less restrictive version requiring more axioms. (Revised by Gino Giotto, 17-Nov-2024.) |
Ref | Expression |
---|---|
cbvmptv.1 | ⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶) |
Ref | Expression |
---|---|
cbvmptv | ⊢ (𝑥 ∈ 𝐴 ↦ 𝐵) = (𝑦 ∈ 𝐴 ↦ 𝐶) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eleq1w 2821 | . . . 4 ⊢ (𝑥 = 𝑦 → (𝑥 ∈ 𝐴 ↔ 𝑦 ∈ 𝐴)) | |
2 | cbvmptv.1 | . . . . 5 ⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶) | |
3 | 2 | eqeq2d 2749 | . . . 4 ⊢ (𝑥 = 𝑦 → (𝑧 = 𝐵 ↔ 𝑧 = 𝐶)) |
4 | 1, 3 | anbi12d 630 | . . 3 ⊢ (𝑥 = 𝑦 → ((𝑥 ∈ 𝐴 ∧ 𝑧 = 𝐵) ↔ (𝑦 ∈ 𝐴 ∧ 𝑧 = 𝐶))) |
5 | 4 | cbvopab1v 5149 | . 2 ⊢ {〈𝑥, 𝑧〉 ∣ (𝑥 ∈ 𝐴 ∧ 𝑧 = 𝐵)} = {〈𝑦, 𝑧〉 ∣ (𝑦 ∈ 𝐴 ∧ 𝑧 = 𝐶)} |
6 | df-mpt 5154 | . 2 ⊢ (𝑥 ∈ 𝐴 ↦ 𝐵) = {〈𝑥, 𝑧〉 ∣ (𝑥 ∈ 𝐴 ∧ 𝑧 = 𝐵)} | |
7 | df-mpt 5154 | . 2 ⊢ (𝑦 ∈ 𝐴 ↦ 𝐶) = {〈𝑦, 𝑧〉 ∣ (𝑦 ∈ 𝐴 ∧ 𝑧 = 𝐶)} | |
8 | 5, 6, 7 | 3eqtr4i 2776 | 1 ⊢ (𝑥 ∈ 𝐴 ↦ 𝐵) = (𝑦 ∈ 𝐴 ↦ 𝐶) |
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