Theorem pwjust 4380

Description: Soundness justification theorem for df-pw 4381. (Contributed by Rodolfo Medina, 28-Apr-2010.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)

Assertion

Ref	Expression
pwjust	⊢ {𝑥 ∣ 𝑥 ⊆ 𝐴} = {𝑦 ∣ 𝑦 ⊆ 𝐴}

Distinct variable groups:   𝑥,𝐴   𝑦,𝐴

Proof of Theorem pwjust

Dummy variable 𝑧 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		sseq1 3845	. . 3 ⊢ (𝑥 = 𝑧 → (𝑥 ⊆ 𝐴 ↔ 𝑧 ⊆ 𝐴))
2	1	cbvabv 2914	. 2 ⊢ {𝑥 ∣ 𝑥 ⊆ 𝐴} = {𝑧 ∣ 𝑧 ⊆ 𝐴}
3		sseq1 3845	. . 3 ⊢ (𝑧 = 𝑦 → (𝑧 ⊆ 𝐴 ↔ 𝑦 ⊆ 𝐴))
4	3	cbvabv 2914	. 2 ⊢ {𝑧 ∣ 𝑧 ⊆ 𝐴} = {𝑦 ∣ 𝑦 ⊆ 𝐴}
5	2, 4	eqtri 2802	1 ⊢ {𝑥 ∣ 𝑥 ⊆ 𝐴} = {𝑦 ∣ 𝑦 ⊆ 𝐴}

Syntax hints:   = wceq 1601  {cab 2763   ⊆ wss 3792

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1839  ax-4 1853  ax-5 1953  ax-6 2021  ax-7 2055  ax-9 2116  ax-10 2135  ax-11 2150  ax-12 2163  ax-ext 2754

This theorem depends on definitions:  df-bi 199  df-an 387  df-or 837  df-tru 1605  df-ex 1824  df-nf 1828  df-sb 2012  df-clab 2764  df-cleq 2770  df-clel 2774  df-in 3799  df-ss 3806

This theorem is referenced by: (None)