Theorem unisn0 45509

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 3944	. 2 ⊢ {∅} ⊆ {∅}
2		uni0b 4871	. 2 ⊢ (∪ {∅} = ∅ ↔ {∅} ⊆ {∅})
3	1, 2	mpbir 232	1 ⊢ ∪ {∅} = ∅

Syntax hints:   = wceq 1547   ⊆ wss 3890  ∅c0 4268  {csn 4562  ∪ cuni 4845

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1802  ax-4 1816  ax-5 1917  ax-6 1974  ax-7 2015  ax-8 2121  ax-9 2129  ax-11 2168  ax-ext 2712

This theorem depends on definitions:  df-bi 208  df-an 397  df-tru 1550  df-fal 1560  df-ex 1787  df-sb 2074  df-clab 2719  df-cleq 2732  df-clel 2815  df-ral 3055  df-rex 3065  df-v 3434  df-dif 3893  df-ss 3907  df-nul 4269  df-sn 4563  df-uni 4846

This theorem is referenced by:  founiiun0  45644  prsal  46768