Theorem disj3 4455

Description: Two ways of saying that two classes are disjoint. (Contributed by NM, 19-May-1998.)

Assertion

Ref	Expression
disj3	⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ 𝐴 = (𝐴 ∖ 𝐵))

Proof of Theorem disj3

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		pm4.71 556	. . . 4 ⊢ ((𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)))
2		eldif 3954	. . . . 5 ⊢ (𝑥 ∈ (𝐴 ∖ 𝐵) ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵))
3	2	bibi2i 336	. . . 4 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)))
4	1, 3	bitr4i 277	. . 3 ⊢ ((𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
5	4	albii 1813	. 2 ⊢ (∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
6		disj1 4452	. 2 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ ∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
7		dfcleq 2718	. 2 ⊢ (𝐴 = (𝐴 ∖ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
8	5, 6, 7	3bitr4i 302	1 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ 𝐴 = (𝐴 ∖ 𝐵))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 205   ∧ wa 394  ∀wal 1531   = wceq 1533   ∈ wcel 2098   ∖ cdif 3941   ∩ cin 3943  ∅c0 4322

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-ext 2696

This theorem depends on definitions:  df-bi 206  df-an 395  df-tru 1536  df-fal 1546  df-ex 1774  df-sb 2060  df-clab 2703  df-cleq 2717  df-clel 2802  df-ral 3051  df-v 3463  df-dif 3947  df-in 3951  df-nul 4323

This theorem is referenced by:  disjel  4458  disj4  4460  uneqdifeq  4494  difprsn1  4805  diftpsn3  4807  ssunsn2  4832  orddif  6467  php  9235  phpOLD  9247  hartogslem1  9567  infeq5i  9661  cantnfp1lem3  9705  dju1dif  10197  infdju1  10214  ssxr  11315  dprd2da  20011  dmdprdsplit2lem  20014  ablfac1eulem  20041  lbsextlem4  21061  opsrtoslem2  22022  alexsublem  23992  volun  25518  lhop1lem  25990  ex-dif  30305  difeq  32394  imadifxp  32470  disjdsct  32564  fzodif1  32643  carsgclctunlem1  34065  probun  34167  ballotlemfp1  34239  bj-disj2r  36635  topdifinfeq  36957  finixpnum  37206  lindsadd  37214  poimirlem11  37232  poimirlem12  37233  poimirlem13  37234  poimirlem14  37235  poimirlem16  37237  poimirlem18  37239  poimirlem21  37242  poimirlem22  37243  poimirlem27  37248  asindmre  37304  kelac2  42628  pwfi2f1o  42659  iccdifioo  45035  iccdifprioo  45036