Theorem bj-velpwALT 37655

Description: This theorem bj-velpwALT 37655 and the next theorem bj-elpwgALT 37656 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 2211. In other cases, that order is better (e.g., vsnex 5406 proved before snexg 5411). (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 2853	. 2 ⊢ (𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ∈ {𝑥 ∣ 𝑥 ⊆ 𝐴})
3		abid 2743	. 2 ⊢ (𝑥 ∈ {𝑥 ∣ 𝑥 ⊆ 𝐴} ↔ 𝑥 ⊆ 𝐴)
4	2, 3	bitri 278	1 ⊢ (𝑥 ∈ 𝒫 𝐴 ↔ 𝑥 ⊆ 𝐴)

Syntax hints:   ↔ wb 209   ∈ wcel 2141  {cab 2739   ⊆ wss 3904  𝒫 cpw 4561

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1823  ax-4 1837  ax-5 1938  ax-6 1995  ax-7 2036  ax-8 2143  ax-9 2151  ax-12 2211  ax-ext 2733

This theorem depends on definitions:  df-bi 210  df-an 401  df-ex 1808  df-sb 2095  df-clab 2740  df-cleq 2753  df-clel 2836  df-pw 4563

This theorem is referenced by:  bj-elpwgALT  37656