Theorem wunsn 10669

Description: A weak universe is closed under singletons. (Contributed by Mario Carneiro, 2-Jan-2017.)

Hypotheses

Ref	Expression
wununi.1	⊢ (𝜑 → 𝑈 ∈ WUni)
wununi.2	⊢ (𝜑 → 𝐴 ∈ 𝑈)

Assertion

Ref	Expression
wunsn	⊢ (𝜑 → {𝐴} ∈ 𝑈)

Proof of Theorem wunsn

Step	Hyp	Ref	Expression
1		dfsn2 4602	. 2 ⊢ {𝐴} = {𝐴, 𝐴}
2		wununi.1	. . 3 ⊢ (𝜑 → 𝑈 ∈ WUni)
3		wununi.2	. . 3 ⊢ (𝜑 → 𝐴 ∈ 𝑈)
4	2, 3, 3	wunpr 10662	. 2 ⊢ (𝜑 → {𝐴, 𝐴} ∈ 𝑈)
5	1, 4	eqeltrid 2832	1 ⊢ (𝜑 → {𝐴} ∈ 𝑈)

Syntax hints:   → wi 4   ∈ wcel 2109  {csn 4589  {cpr 4591  WUnicwun 10653

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-ext 2701

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1543  df-ex 1780  df-sb 2066  df-clab 2708  df-cleq 2721  df-clel 2803  df-ne 2926  df-ral 3045  df-rex 3054  df-v 3449  df-un 3919  df-ss 3931  df-sn 4590  df-pr 4592  df-uni 4872  df-tr 5215  df-wun 10655

This theorem is referenced by:  wunsuc  10670  wunfi  10674  wunop  10675  wuntpos  10687  wunsets  17147  1strwunbndx  17195  catcoppccl  18079