Theorem cbvmpt21 39278

Description: Rule to change the first bound variable in a maps-to function, using implicit substitution. (Contributed by Glauco Siliprandi, 26-Jun-2021.)

Hypotheses

Ref	Expression
cbvmpt21.1	⊢ Ⅎ𝑥𝐵
cbvmpt21.2	⊢ Ⅎ𝑧𝐵
cbvmpt21.3	⊢ Ⅎ𝑧𝐶
cbvmpt21.4	⊢ Ⅎ𝑥𝐸
cbvmpt21.5	⊢ (𝑥 = 𝑧 → 𝐶 = 𝐸)

Assertion

Ref	Expression
cbvmpt21	⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = (𝑧 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐸)

Distinct variable groups:   𝑥,𝐴,𝑧   𝑥,𝑦,𝑧

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

Proof of Theorem cbvmpt21

Dummy variable 𝑢 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		nfv 1843	. . . . 5 ⊢ Ⅎ𝑧 𝑥 ∈ 𝐴
2		cbvmpt21.2	. . . . . 6 ⊢ Ⅎ𝑧𝐵
3	2	nfcri 2758	. . . . 5 ⊢ Ⅎ𝑧 𝑦 ∈ 𝐵
4	1, 3	nfan 1828	. . . 4 ⊢ Ⅎ𝑧(𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)
5		cbvmpt21.3	. . . . 5 ⊢ Ⅎ𝑧𝐶
6	5	nfeq2 2780	. . . 4 ⊢ Ⅎ𝑧 𝑢 = 𝐶
7	4, 6	nfan 1828	. . 3 ⊢ Ⅎ𝑧((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐶)
8		nfv 1843	. . . . 5 ⊢ Ⅎ𝑥 𝑧 ∈ 𝐴
9		nfcv 2764	. . . . . 6 ⊢ Ⅎ𝑥𝑦
10		cbvmpt21.1	. . . . . 6 ⊢ Ⅎ𝑥𝐵
11	9, 10	nfel 2777	. . . . 5 ⊢ Ⅎ𝑥 𝑦 ∈ 𝐵
12	8, 11	nfan 1828	. . . 4 ⊢ Ⅎ𝑥(𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)
13		cbvmpt21.4	. . . . 5 ⊢ Ⅎ𝑥𝐸
14	13	nfeq2 2780	. . . 4 ⊢ Ⅎ𝑥 𝑢 = 𝐸
15	12, 14	nfan 1828	. . 3 ⊢ Ⅎ𝑥((𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐸)
16		eleq1 2689	. . . . 5 ⊢ (𝑥 = 𝑧 → (𝑥 ∈ 𝐴 ↔ 𝑧 ∈ 𝐴))
17	16	anbi1d 741	. . . 4 ⊢ (𝑥 = 𝑧 → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ↔ (𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)))
18		cbvmpt21.5	. . . . 5 ⊢ (𝑥 = 𝑧 → 𝐶 = 𝐸)
19	18	eqeq2d 2632	. . . 4 ⊢ (𝑥 = 𝑧 → (𝑢 = 𝐶 ↔ 𝑢 = 𝐸))
20	17, 19	anbi12d 747	. . 3 ⊢ (𝑥 = 𝑧 → (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐶) ↔ ((𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐸)))
21	7, 15, 20	cbvoprab1 6727	. 2 ⊢ {⟨⟨𝑥, 𝑦⟩, 𝑢⟩ ∣ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐶)} = {⟨⟨𝑧, 𝑦⟩, 𝑢⟩ ∣ ((𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐸)}
22		df-mpt2 6655	. 2 ⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = {⟨⟨𝑥, 𝑦⟩, 𝑢⟩ ∣ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐶)}
23		df-mpt2 6655	. 2 ⊢ (𝑧 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐸) = {⟨⟨𝑧, 𝑦⟩, 𝑢⟩ ∣ ((𝑧 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑢 = 𝐸)}
24	21, 22, 23	3eqtr4i 2654	1 ⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = (𝑧 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐸)

Syntax hints:   → wi 4   ∧ wa 384   = wceq 1483   ∈ wcel 1990  Ⅎwnfc 2751  {coprab 6651   ↦ cmpt2 6652

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pr 4906

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-rab 2921  df-v 3202  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-nul 3916  df-if 4087  df-sn 4178  df-pr 4180  df-op 4184  df-opab 4713  df-oprab 6654  df-mpt2 6655

This theorem is referenced by: (None)