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Theorem bj-sngltag 34309
Description: The singletonization and the tagging of a set contain the same singletons. (Contributed by BJ, 6-Oct-2018.)
Assertion
Ref Expression
bj-sngltag (𝐴𝑉 → ({𝐴} ∈ sngl 𝐵 ↔ {𝐴} ∈ tag 𝐵))

Proof of Theorem bj-sngltag
StepHypRef Expression
1 bj-sngltagi 34308 . 2 ({𝐴} ∈ sngl 𝐵 → {𝐴} ∈ tag 𝐵)
2 df-bj-tag 34301 . . . 4 tag 𝐵 = (sngl 𝐵 ∪ {∅})
32eleq2i 2902 . . 3 ({𝐴} ∈ tag 𝐵 ↔ {𝐴} ∈ (sngl 𝐵 ∪ {∅}))
4 elun 4101 . . . 4 ({𝐴} ∈ (sngl 𝐵 ∪ {∅}) ↔ ({𝐴} ∈ sngl 𝐵 ∨ {𝐴} ∈ {∅}))
5 idd 24 . . . . 5 (𝐴𝑉 → ({𝐴} ∈ sngl 𝐵 → {𝐴} ∈ sngl 𝐵))
6 elsni 4558 . . . . . 6 ({𝐴} ∈ {∅} → {𝐴} = ∅)
7 snprc 4627 . . . . . . 7 𝐴 ∈ V ↔ {𝐴} = ∅)
8 elex 3491 . . . . . . . 8 (𝐴𝑉𝐴 ∈ V)
98pm2.24d 154 . . . . . . 7 (𝐴𝑉 → (¬ 𝐴 ∈ V → {𝐴} ∈ sngl 𝐵))
107, 9syl5bir 245 . . . . . 6 (𝐴𝑉 → ({𝐴} = ∅ → {𝐴} ∈ sngl 𝐵))
116, 10syl5 34 . . . . 5 (𝐴𝑉 → ({𝐴} ∈ {∅} → {𝐴} ∈ sngl 𝐵))
125, 11jaod 855 . . . 4 (𝐴𝑉 → (({𝐴} ∈ sngl 𝐵 ∨ {𝐴} ∈ {∅}) → {𝐴} ∈ sngl 𝐵))
134, 12syl5bi 244 . . 3 (𝐴𝑉 → ({𝐴} ∈ (sngl 𝐵 ∪ {∅}) → {𝐴} ∈ sngl 𝐵))
143, 13syl5bi 244 . 2 (𝐴𝑉 → ({𝐴} ∈ tag 𝐵 → {𝐴} ∈ sngl 𝐵))
151, 14impbid2 228 1 (𝐴𝑉 → ({𝐴} ∈ sngl 𝐵 ↔ {𝐴} ∈ tag 𝐵))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 208  wo 843   = wceq 1537  wcel 2114  Vcvv 3473  cun 3910  c0 4267  {csn 4541  sngl bj-csngl 34291  tag bj-ctag 34300
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 1911  ax-6 1970  ax-7 2015  ax-8 2116  ax-9 2124  ax-10 2145  ax-11 2161  ax-12 2177  ax-ext 2792
This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-tru 1540  df-ex 1781  df-nf 1785  df-sb 2070  df-clab 2799  df-cleq 2813  df-clel 2891  df-nfc 2959  df-v 3475  df-dif 3915  df-un 3917  df-in 3919  df-ss 3928  df-nul 4268  df-sn 4542  df-bj-tag 34301
This theorem is referenced by:  bj-tagcg  34311  bj-taginv  34312
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