Theorem unisn0 44203

Description: The union of the singleton of the empty set is the empty set. (Contributed by Glauco Siliprandi, 17-Aug-2020.)

Assertion

Ref	Expression
unisn0	⊢ ∪ {∅} = ∅

Proof of Theorem unisn0

Step	Hyp	Ref	Expression
1		ssid 4004	. 2 ⊢ {∅} ⊆ {∅}
2		uni0b 4937	. 2 ⊢ (∪ {∅} = ∅ ↔ {∅} ⊆ {∅})
3	1, 2	mpbir 230	1 ⊢ ∪ {∅} = ∅

Syntax hints:   = wceq 1540   ⊆ wss 3948  ∅c0 4322  {csn 4628  ∪ cuni 4908

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1912  ax-6 1970  ax-7 2010  ax-8 2107  ax-9 2115  ax-11 2153  ax-ext 2702

This theorem depends on definitions:  df-bi 206  df-an 396  df-tru 1543  df-fal 1553  df-ex 1781  df-sb 2067  df-clab 2709  df-cleq 2723  df-clel 2809  df-ral 3061  df-rex 3070  df-v 3475  df-dif 3951  df-in 3955  df-ss 3965  df-nul 4323  df-sn 4629  df-uni 4909

This theorem is referenced by:  founiiun0  44348  prsal  45493