Theorem unisn0 45598

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 3958	. 2 ⊢ {∅} ⊆ {∅}
2		uni0b 4891	. 2 ⊢ (∪ {∅} = ∅ ↔ {∅} ⊆ {∅})
3	1, 2	mpbir 233	1 ⊢ ∪ {∅} = ∅

Syntax hints:   = wceq 1559   ⊆ wss 3904  ∅c0 4285  {csn 4581  ∪ cuni 4864

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1814  ax-4 1828  ax-5 1929  ax-6 1986  ax-7 2027  ax-8 2143  ax-9 2151  ax-11 2190  ax-ext 2733

This theorem depends on definitions:  df-bi 209  df-an 400  df-tru 1562  df-fal 1572  df-ex 1799  df-sb 2090  df-clab 2740  df-cleq 2753  df-clel 2836  df-ral 3076  df-rex 3086  df-v 3455  df-dif 3907  df-ss 3921  df-nul 4286  df-sn 4582  df-uni 4865

This theorem is referenced by:  founiiun0  45732  prsal  46856