Theorem unisn0 45815

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 3962	. 2 ⊢ {∅} ⊆ {∅}
2		uni0b 4904	. 2 ⊢ (∪ {∅} = ∅ ↔ {∅} ⊆ {∅})
3	1, 2	mpbir 234	1 ⊢ ∪ {∅} = ∅

This proof depends on syntax axioms:   = wceq 1570   ⊆ wss 3908  ∅c0 4289  {csn 4594  ∪ cuni 4877

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2148  ax-9 2156  ax-11 2195  ax-ext 2738

This proof depends on definitions:  df-bi 210  df-an 402  df-tru 1573  df-fal 1583  df-ex 1813  df-sb 2100  df-clab 2745  df-cleq 2758  df-clel 2841  df-ral 3083  df-rex 3093  df-v 3460  df-dif 3911  df-ss 3925  df-nul 4290  df-sn 4595  df-uni 4878

This theorem is used by:  founiiun0  45949  prsal  47073