Theorem cbveuw 2636

Description: Version of cbveu 2637 with a disjoint variable condition, which does not require ax-10 2179, ax-13 2406. (Contributed by NM, 25-Nov-1994.) (Revised by GG, 23-May-2024.)

Hypotheses

Ref	Expression
cbveuw.1	⊢ Ⅎ𝑦𝜑
cbveuw.2	⊢ Ⅎ𝑥𝜓
cbveuw.3	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
cbveuw	⊢ (∃!𝑥𝜑 ↔ ∃!𝑦𝜓)

Distinct variable group:   𝑥,𝑦

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

Proof of Theorem cbveuw

Step	Hyp	Ref	Expression
1		cbveuw.1	. . . 4 ⊢ Ⅎ𝑦𝜑
2		cbveuw.2	. . . 4 ⊢ Ⅎ𝑥𝜓
3		cbveuw.3	. . . 4 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
4	1, 2, 3	cbvexv1 2376	. . 3 ⊢ (∃𝑥𝜑 ↔ ∃𝑦𝜓)
5	1, 2, 3	cbvmow 2633	. . 3 ⊢ (∃*𝑥𝜑 ↔ ∃*𝑦𝜓)
6	4, 5	anbi12i 640	. 2 ⊢ ((∃𝑥𝜑 ∧ ∃*𝑥𝜑) ↔ (∃𝑦𝜓 ∧ ∃*𝑦𝜓))
7		df-eu 2599	. 2 ⊢ (∃!𝑥𝜑 ↔ (∃𝑥𝜑 ∧ ∃*𝑥𝜑))
8		df-eu 2599	. 2 ⊢ (∃!𝑦𝜓 ↔ (∃𝑦𝜓 ∧ ∃*𝑦𝜓))
9	6, 7, 8	3bitr4i 306	1 ⊢ (∃!𝑥𝜑 ↔ ∃!𝑦𝜓)

This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ wa 401  ∃wex 1812  Ⅎwnf 1816  ∃*wmo 2567  ∃!weu 2598

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-11 2195  ax-12 2216

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-ex 1813  df-nf 1817  df-mo 2569  df-eu 2599

This theorem is used by:  tz6.12f  6910  f1ompt  7110  climeu  15632  initoeu2  18097