Theorem cbvrexv2 3932

Description: Rule used to change the bound variable in a restricted existential quantifier with implicit substitution which also changes the quantifier domain. Usage of this theorem is discouraged because it depends on ax-13 2390. (Contributed by David Moews, 1-May-2017.) (New usage is discouraged.)

Hypotheses

Ref	Expression
cbvralv2.1	⊢ (𝑥 = 𝑦 → (𝜓 ↔ 𝜒))
cbvralv2.2	⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵)

Assertion

Ref	Expression
cbvrexv2	⊢ (∃𝑥 ∈ 𝐴 𝜓 ↔ ∃𝑦 ∈ 𝐵 𝜒)

Distinct variable groups:   𝑦,𝐴   𝜓,𝑦   𝑥,𝐵   𝜒,𝑥

Allowed substitution hints:   𝜓(𝑥)   𝜒(𝑦)   𝐴(𝑥)   𝐵(𝑦)

Proof of Theorem cbvrexv2

Step	Hyp	Ref	Expression
1		nfcv 2979	. 2 ⊢ Ⅎ𝑦𝐴
2		nfcv 2979	. 2 ⊢ Ⅎ𝑥𝐵
3		nfv 1915	. 2 ⊢ Ⅎ𝑦𝜓
4		nfv 1915	. 2 ⊢ Ⅎ𝑥𝜒
5		cbvralv2.2	. 2 ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵)
6		cbvralv2.1	. 2 ⊢ (𝑥 = 𝑦 → (𝜓 ↔ 𝜒))
7	1, 2, 3, 4, 5, 6	cbvrexcsf 3928	1 ⊢ (∃𝑥 ∈ 𝐴 𝜓 ↔ ∃𝑦 ∈ 𝐵 𝜒)

Syntax hints:   → wi 4   ↔ wb 208   = wceq 1537  ∃wrex 3141

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2116  ax-9 2124  ax-10 2145  ax-11 2161  ax-12 2177  ax-13 2390  ax-ext 2795

This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-tru 1540  df-ex 1781  df-nf 1785  df-sb 2070  df-clab 2802  df-cleq 2816  df-clel 2895  df-nfc 2965  df-ral 3145  df-rex 3146  df-sbc 3775  df-csb 3886

This theorem is referenced by: (None)