Theorem cbvcsbv 3850

Description: Change the bound variable of a proper substitution into a class using implicit substitution. (Contributed by NM, 30-Sep-2008.) (Revised by Mario Carneiro, 13-Oct-2016.)

Hypothesis

Ref	Expression
cbvcsbv.1	⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶)

Assertion

Ref	Expression
cbvcsbv	⊢ ⦋𝐴 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑦⦌𝐶

Distinct variable groups:   𝑥,𝑦   𝑦,𝐵   𝑥,𝐶

Allowed substitution hints:   𝐴(𝑥,𝑦)   𝐵(𝑥)   𝐶(𝑦)

Proof of Theorem cbvcsbv

Dummy variable 𝑧 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		cbvcsbv.1	. . . . 5 ⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶)
2	1	eleq2d 2823	. . . 4 ⊢ (𝑥 = 𝑦 → (𝑧 ∈ 𝐵 ↔ 𝑧 ∈ 𝐶))
3	2	cbvsbcvw 3763	. . 3 ⊢ ([𝐴 / 𝑥]𝑧 ∈ 𝐵 ↔ [𝐴 / 𝑦]𝑧 ∈ 𝐶)
4	3	abbii 2804	. 2 ⊢ {𝑧 ∣ [𝐴 / 𝑥]𝑧 ∈ 𝐵} = {𝑧 ∣ [𝐴 / 𝑦]𝑧 ∈ 𝐶}
5		df-csb 3839	. 2 ⊢ ⦋𝐴 / 𝑥⦌𝐵 = {𝑧 ∣ [𝐴 / 𝑥]𝑧 ∈ 𝐵}
6		df-csb 3839	. 2 ⊢ ⦋𝐴 / 𝑦⦌𝐶 = {𝑧 ∣ [𝐴 / 𝑦]𝑧 ∈ 𝐶}
7	4, 5, 6	3eqtr4i 2770	1 ⊢ ⦋𝐴 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑦⦌𝐶

Syntax hints:   → wi 4   = wceq 1542   ∈ wcel 2114  {cab 2715  [wsbc 3729  ⦋csb 3838

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-8 2116  ax-9 2124  ax-ext 2709

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1782  df-sb 2069  df-clab 2716  df-cleq 2729  df-clel 2812  df-sbc 3730  df-csb 3839

This theorem is referenced by:  cbvsumv  15649  cbvprodv  15870  pmatcollpw3lem  22758  precsexlemcbv  28212  cbvprodvw2  36445  poimirlem27  37982  cdleme40v  40929