Theorem disjin 29962

Description: If a collection is disjoint, so is the collection of the intersections with a given set. (Contributed by Thierry Arnoux, 14-Feb-2017.)

Assertion

Ref	Expression
disjin	⊢ (Disj 𝑥 ∈ 𝐵 𝐶 → Disj 𝑥 ∈ 𝐵 (𝐶 ∩ 𝐴))

Proof of Theorem disjin

Dummy variable 𝑦 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		elinel1 4021	. . . . . 6 ⊢ (𝑦 ∈ (𝐶 ∩ 𝐴) → 𝑦 ∈ 𝐶)
2	1	anim2i 610	. . . . 5 ⊢ ((𝑥 ∈ 𝐵 ∧ 𝑦 ∈ (𝐶 ∩ 𝐴)) → (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐶))
3	2	ax-gen 1839	. . . 4 ⊢ ∀𝑥((𝑥 ∈ 𝐵 ∧ 𝑦 ∈ (𝐶 ∩ 𝐴)) → (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐶))
4	3	rmoimi2 3622	. . 3 ⊢ (∃*𝑥 ∈ 𝐵 𝑦 ∈ 𝐶 → ∃*𝑥 ∈ 𝐵 𝑦 ∈ (𝐶 ∩ 𝐴))
5	4	alimi 1855	. 2 ⊢ (∀𝑦∃*𝑥 ∈ 𝐵 𝑦 ∈ 𝐶 → ∀𝑦∃*𝑥 ∈ 𝐵 𝑦 ∈ (𝐶 ∩ 𝐴))
6		df-disj 4855	. 2 ⊢ (Disj 𝑥 ∈ 𝐵 𝐶 ↔ ∀𝑦∃*𝑥 ∈ 𝐵 𝑦 ∈ 𝐶)
7		df-disj 4855	. 2 ⊢ (Disj 𝑥 ∈ 𝐵 (𝐶 ∩ 𝐴) ↔ ∀𝑦∃*𝑥 ∈ 𝐵 𝑦 ∈ (𝐶 ∩ 𝐴))
8	5, 6, 7	3imtr4i 284	1 ⊢ (Disj 𝑥 ∈ 𝐵 𝐶 → Disj 𝑥 ∈ 𝐵 (𝐶 ∩ 𝐴))

Syntax hints:   → wi 4   ∧ wa 386  ∀wal 1599   ∈ wcel 2106  ∃*wrmo 3092   ∩ cin 3790  Disj wdisj 4854

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1839  ax-4 1853  ax-5 1953  ax-6 2021  ax-7 2054  ax-9 2115  ax-10 2134  ax-11 2149  ax-12 2162  ax-ext 2753

This theorem depends on definitions:  df-bi 199  df-an 387  df-or 837  df-tru 1605  df-ex 1824  df-nf 1828  df-sb 2012  df-mo 2550  df-clab 2763  df-cleq 2769  df-clel 2773  df-nfc 2920  df-rmo 3097  df-v 3399  df-in 3798  df-disj 4855

This theorem is referenced by:  measinblem  30881  carsgclctunlem2  30979