Theorem vextru 2721

Description: Every setvar is a member of {𝑥 ∣ ⊤}, which is therefore "a" universal class. Once class extensionality dfcleq 2730 is available, we can say "the" universal class (see df-v 3482). This is sbtru 2067 expressed using class abstractions. (Contributed by BJ, 2-Sep-2023.)

Assertion

Ref	Expression
vextru	⊢ 𝑦 ∈ {𝑥 ∣ ⊤}

Proof of Theorem vextru

Step	Hyp	Ref	Expression
1		tru 1544	. 2 ⊢ ⊤
2	1	vexw 2720	1 ⊢ 𝑦 ∈ {𝑥 ∣ ⊤}

Syntax hints:  ⊤wtru 1541   ∈ wcel 2108  {cab 2714

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795

This theorem depends on definitions:  df-bi 207  df-tru 1543  df-sb 2065  df-clab 2715

This theorem is referenced by:  issettru  2819  vex  3484  abv  3492  ab0orv  4383  bj-denoteslem  36872  bj-vjust  37056