Theorem bj-velpwALT 37717

Description: This theorem bj-velpwALT 37717 and the next theorem bj-elpwgALT 37718 are alternate proofs of velpw 4566 and elpwg 4564 respectively, where one proves first the setvar case and then generalizes using vtoclbg 3523 instead of proving first the general case using elab2g 3638 and then specifying. Here, this results in needing an extra DV condition, a longer combined proof and use of ax-12 2212. In other cases, that order is better (e.g., vsnex 5405 proved before snexg 5410). (Contributed by BJ, 17-Jan-2025.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
bj-velpwALT	⊢ (𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ⊆ 𝐴)

Distinct variable group:   𝑥,𝐴

Proof of Theorem bj-velpwALT

Step	Hyp	Ref	Expression
1		df-pw 4563	. . 3 ⊢ 𝒫 𝐴 = {𝑥 ∣ 𝑥 ⊆ 𝐴}
2	1	eleq2i 2854	. 2 ⊢ (𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ∈ {𝑥 ∣ 𝑥 ⊆ 𝐴})
3		abid 2744	. 2 ⊢ (𝑥 ∈ {𝑥 ∣ 𝑥 ⊆ 𝐴} ↔ 𝑥 ⊆ 𝐴)
4	2, 3	bitri 278	1 ⊢ (𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ⊆ 𝐴)

This proof depends on syntax axioms:   ↔ wb 209   ∈ wcel 2142  {cab 2740   ⊆ wss 3904  𝒫 cpw 4561

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1824  ax-4 1838  ax-5 1939  ax-6 1996  ax-7 2037  ax-8 2144  ax-9 2152  ax-12 2212  ax-ext 2734

This proof depends on definitions:  df-bi 210  df-an 401  df-ex 1809  df-sb 2096  df-clab 2741  df-cleq 2754  df-clel 2837  df-pw 4563

This theorem is used by:  bj-elpwgALT  37718