Theorem bj-adjfrombun 38052

Description: Adjunction from singleton and binary union. (Contributed by BJ, 19-Jan-2025.) (Proof modification is discouraged.)

Assertion

Ref	Expression
bj-adjfrombun	⊢ (𝑥 ∪ {𝑦}) ∈ V

Proof of Theorem bj-adjfrombun

Step	Hyp	Ref	Expression
1		vex 3454	. 2 ⊢ 𝑥 ∈ V
2		bj-snexg 38040	. . 3 ⊢ (𝑦 ∈ V → {𝑦} ∈ V)
3	2	elv 3455	. 2 ⊢ {𝑦} ∈ V
4		bj-unexg 38044	. 2 ⊢ ((𝑥 ∈ V ∧ {𝑦} ∈ V) → (𝑥 ∪ {𝑦}) ∈ V)
5	1, 3, 4	mp2an 705	1 ⊢ (𝑥 ∪ {𝑦}) ∈ V

This proof depends on syntax axioms:   ∈ wcel 2144  Vcvv 3450   ∪ cun 4149  {csn 4584

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-8 2146  ax-9 2154  ax-12 2212  ax-ext 2732  ax-bj-sn 38039  ax-bj-bun 38043

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-tru 1572  df-ex 1812  df-sb 2099  df-clab 2739  df-cleq 2752  df-clel 2835  df-v 3452  df-un 4151  df-sn 4585

This theorem is used by: (None)