Theorem disj 4411

Description: Two ways of saying that two classes are disjoint (have no members in common). (Contributed by NM, 17-Feb-2004.) Avoid ax-10 2176, ax-11 2192, ax-12 2213. (Revised by GG, 28-Jun-2024.)

Assertion

Ref	Expression
disj	⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ ∀𝑥 ∈ 𝐴 ¬ 𝑥 ∈ 𝐵)

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Proof of Theorem disj

Dummy variable 𝑦 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		df-in 3913	. . . 4 ⊢ (𝐴 ∩ 𝐵) = {𝑦 ∣ (𝑦 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)}
2	1	eqeq1i 2768	. . 3 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ {𝑦 ∣ (𝑦 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)} = ∅)
3		eleq1w 2846	. . . . 5 ⊢ (𝑦 = 𝑥 → (𝑦 ∈ 𝐴 ↔ 𝑥 ∈ 𝐴))
4		eleq1w 2846	. . . . 5 ⊢ (𝑦 = 𝑥 → (𝑦 ∈ 𝐵 ↔ 𝑥 ∈ 𝐵))
5	3, 4	anbi12d 643	. . . 4 ⊢ (𝑦 = 𝑥 → ((𝑦 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵)))
6	5	eqabcbw 2837	. . 3 ⊢ ({𝑦 ∣ (𝑦 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)} = ∅ ↔ ∀𝑥((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ 𝑥 ∈ ∅))
7		imnan 404	. . . . 5 ⊢ ((𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵) ↔ ¬ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵))
8		noel 4292	. . . . . 6 ⊢ ¬ 𝑥 ∈ ∅
9	8	nbn 375	. . . . 5 ⊢ (¬ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ ((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ 𝑥 ∈ ∅))
10	7, 9	bitr2i 279	. . . 4 ⊢ (((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ 𝑥 ∈ ∅) ↔ (𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
11	10	albii 1849	. . 3 ⊢ (∀𝑥((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ 𝑥 ∈ ∅) ↔ ∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
12	2, 6, 11	3bitri 300	. 2 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ ∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
13		df-ral 3080	. 2 ⊢ (∀𝑥 ∈ 𝐴 ¬ 𝑥 ∈ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → ¬ 𝑥 ∈ 𝐵))
14	12, 13	bitr4i 281	1 ⊢ ((𝐴 ∩ 𝐵) = ∅ ↔ ∀𝑥 ∈ 𝐴 ¬ 𝑥 ∈ 𝐵)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 209   ∧ wa 400  ∀wal 1568   = wceq 1570   ∈ wcel 2143  {cab 2741  ∀wral 3079   ∩ cin 3905  ∅c0 4287

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1825  ax-4 1839  ax-5 1940  ax-6 1997  ax-7 2038  ax-8 2145  ax-9 2153  ax-ext 2735

This theorem depends on definitions:  df-bi 210  df-an 401  df-tru 1573  df-fal 1583  df-ex 1810  df-sb 2097  df-clab 2742  df-cleq 2755  df-clel 2838  df-ral 3080  df-dif 3909  df-in 3913  df-nul 4288

This theorem is referenced by:  disjr  4412  disj1  4413  disjne  4416  disjord  5099  disjiund  5101  otiunsndisj  5505  dfpo2  6299  onxpdisj  6490  f0rn0  6765  onint  7790  zfreg  9559  kmlem4  10138  fin23lem30  10327  fin23lem31  10328  isf32lem3  10340  fpwwe2  10629  renfdisj  11270  fvinim0ffz  13820  s3iunsndisj  15007  metdsge  24988  sltsdisj  27974  dfpth2  30056  2wspmdisj  30666  subfacp1lem1  35649  disjabso  45664  dvmptfprodlem  46638  stoweidlem26  46720  stoweidlem59  46753  iundjiunlem  47153  otiunsndisjX  47993  upgrimpths  48651