Theorem ceqsexv2d 3477

Description: Elimination of an existential quantifier, using implicit substitution. (Contributed by Thierry Arnoux, 10-Sep-2016.) Shorten, reduce dv conditions. (Revised by Wolf Lammen, 5-Jun-2025.) (Proof shortened by SN, 5-Jun-2025.)

Hypotheses

Ref	Expression
ceqsexv2d.1	⊢ 𝐴 ∈ V
ceqsexv2d.2	⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
ceqsexv2d.3	⊢ 𝜓

Assertion

Ref	Expression
ceqsexv2d	⊢ ∃𝑥𝜑

Distinct variable group:   𝑥,𝐴

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

Proof of Theorem ceqsexv2d

Step	Hyp	Ref	Expression
1		ceqsexv2d.1	. . 3 ⊢ 𝐴 ∈ V
2	1	isseti 3445	. 2 ⊢ ∃𝑥 𝑥 = 𝐴
3		ceqsexv2d.3	. . 3 ⊢ 𝜓
4		ceqsexv2d.2	. . 3 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
5	3, 4	mpbiri 258	. 2 ⊢ (𝑥 = 𝐴 → 𝜑)
6	2, 5	eximii 1839	1 ⊢ ∃𝑥𝜑

Syntax hints:   → wi 4   ↔ wb 206   = wceq 1542  ∃wex 1781   ∈ wcel 2114  Vcvv 3427

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-8 2116

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1782  df-clel 2810

This theorem is referenced by:  en0  8954  en0r  8956  ensn1  8957  0domg  9031  tz9.1  9639  cplem2  9803  karden  9808  pwmnd  18897  2lgslem1  27345  griedg0prc  29321  1loopgrvd2  29560  bnj150  35006  permaxsep  45422  permaxnul  45423  permaxpow  45424  permaxpr  45425  permaxun  45426  permaxinf2lem  45427  nregmodel  45432  fnchoice  45448  nfermltl8rev  48206  nfermltl2rev  48207  nfermltlrev  48208  gpg5edgnedg  48594  nn0mnd  48643  rrx2xpreen  49183