Theorem cbvrexv 3454

Description: Change the bound variable of a restricted existential quantifier using implicit substitution. See cbvrexvw 3451 based on fewer axioms , but extra disjoint variables. Usage of this theorem is discouraged because it depends on ax-13 2386. Use the weaker cbvrexvw 3451 when possible. (Contributed by NM, 2-Jun-1998.) (New usage is discouraged.)

Hypothesis

Ref	Expression
cbvralv.1	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
cbvrexv	⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑦 ∈ 𝐴 𝜓)

Distinct variable groups:   𝑥,𝐴   𝑦,𝐴   𝜑,𝑦   𝜓,𝑥

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)

Proof of Theorem cbvrexv

Step	Hyp	Ref	Expression
1		nfv 1911	. 2 ⊢ Ⅎ𝑦𝜑
2		nfv 1911	. 2 ⊢ Ⅎ𝑥𝜓
3		cbvralv.1	. 2 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
4	1, 2, 3	cbvrex 3447	1 ⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑦 ∈ 𝐴 𝜓)

Syntax hints:   → wi 4   ↔ wb 208  ∃wrex 3139

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1907  ax-6 1966  ax-7 2011  ax-8 2112  ax-10 2141  ax-11 2156  ax-12 2172  ax-13 2386

This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-tru 1536  df-ex 1777  df-nf 1781  df-sb 2066  df-clel 2893  df-nfc 2963  df-ral 3143  df-rex 3144

This theorem is referenced by:  cbvrex2v  3466  cygablOLD  19005  rexlimdvaacbv  40551  smfsup  43081  smfinflem  43084  smfinf  43085