Theorem cbvex2vw 2036

Description: Rule used to change bound variables, using implicit substitution. Version of cbvex2vv 2408 with more disjoint variable conditions, which requires fewer axioms . (Contributed by NM, 26-Jul-1995.) Avoid ax-13 2366. (Revised by Gino Giotto, 10-Jan-2024.)

Hypothesis

Ref	Expression
cbval2vw.1	⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
cbvex2vw	⊢ (∃𝑥∃𝑦𝜑 ↔ ∃𝑧∃𝑤𝜓)

Distinct variable groups:   𝑧,𝑤,𝜑   𝑥,𝑦,𝜓   𝑥,𝑤,𝑦,𝑧

Allowed substitution hints:   𝜑(𝑥,𝑦)   𝜓(𝑧,𝑤)

Proof of Theorem cbvex2vw

Step	Hyp	Ref	Expression
1		cbval2vw.1	. . 3 ⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (𝜑 ↔ 𝜓))
2	1	cbvexdvaw 2034	. 2 ⊢ (𝑥 = 𝑧 → (∃𝑦𝜑 ↔ ∃𝑤𝜓))
3	2	cbvexvw 2032	1 ⊢ (∃𝑥∃𝑦𝜑 ↔ ∃𝑧∃𝑤𝜓)

Syntax hints:   → wi 4   ↔ wb 205   ∧ wa 394  ∃wex 1773

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003

This theorem depends on definitions:  df-bi 206  df-an 395  df-ex 1774

This theorem is referenced by:  cbvex4vw  2037  cbvopabv  5225  bj-cbvex4vv  36315  funop1  46692  uspgrsprf1  47287