Theorem clel3g 3674

Description: Alternate definition of membership in a set. (Contributed by NM, 13-Aug-2005.)

Assertion

Ref	Expression
clel3g	⊢ (𝐵 ∈ 𝑉 → (𝐴 ∈ 𝐵 ↔ ∃𝑥(𝑥 = 𝐵 ∧ 𝐴 ∈ 𝑥)))

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Allowed substitution hint:   𝑉(𝑥)

Proof of Theorem clel3g

Step	Hyp	Ref	Expression
1		eleq2 2833	. . 3 ⊢ (𝑥 = 𝐵 → (𝐴 ∈ 𝑥 ↔ 𝐴 ∈ 𝐵))
2	1	ceqsexgv 3667	. 2 ⊢ (𝐵 ∈ 𝑉 → (∃𝑥(𝑥 = 𝐵 ∧ 𝐴 ∈ 𝑥) ↔ 𝐴 ∈ 𝐵))
3	2	bicomd 223	1 ⊢ (𝐵 ∈ 𝑉 → (𝐴 ∈ 𝐵 ↔ ∃𝑥(𝑥 = 𝐵 ∧ 𝐴 ∈ 𝑥)))

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1537  ∃wex 1777   ∈ wcel 2108

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-ext 2711

This theorem depends on definitions:  df-bi 207  df-an 396  df-tru 1540  df-ex 1778  df-sb 2065  df-clab 2718  df-cleq 2732  df-clel 2819

This theorem is referenced by:  clel3  3675  uniprg  4947  dfiun2gOLD  5054