Theorem disj3 4405

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		pm4.71 565	. . . 4 ⊢ ((𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)))
2		eldif 3912	. . . . 5 ⊢ (𝑥 ∈ (𝐴 ∖ 𝐵) ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵))
3	2	bibi2i 339	. . . 4 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)))
4	1, 3	bitr4i 280	. . 3 ⊢ ((𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
5	4	albii 1838	. 2 ⊢ (∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
6		disj1 4403	. 2 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ ∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
7		dfcleq 2754	. 2 ⊢ (𝐴 = (𝐴 ∖ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∖ 𝐵)))
8	5, 6, 7	3bitr4i 305	1 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ 𝐴 = (𝐴 ∖ 𝐵))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 208   ∧ wa 399  ∀wal 1557   = wceq 1559   ∈ wcel 2141   ∖ cdif 3899   ∩ cin 3901  ∅c0 4283

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-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-v 3455  df-dif 3905  df-in 3909  df-nul 4284

This theorem is referenced by:  disjel  4408  disj4  4410  uneqdifeq  4443  difprsn1  4757  diftpsn3  4759  ssunsn2  4782  orddif  6439  php  9169  hartogslem1  9484  infeq5i  9585  cantnfp1lem3  9629  dju1dif  10123  infdju1  10140  ssxr  11246  dprd2da  20075  dmdprdsplit2lem  20078  ablfac1eulem  20105  lbsextlem4  21219  opsrtoslem2  22097  alexsublem  24092  volun  25595  lhop1lem  26063  ex-dif  30582  difeq  32677  imadifxp  32761  disjdsct  32866  fzodif1  32955  carsgclctunlem1  34575  probun  34677  ballotlemfp1  34750  bj-disj2r  37474  topdifinfeq  37805  finixpnum  38065  lindsadd  38073  poimirlem11  38091  poimirlem12  38092  poimirlem13  38093  poimirlem14  38094  poimirlem16  38096  poimirlem18  38098  poimirlem21  38101  poimirlem22  38102  poimirlem27  38107  asindmre  38163  kelac2  43603  pwfi2f1o  43634  iccdifioo  46052  iccdifprioo  46053