Theorem difininv 32545

Description: Condition for the intersections of two sets with a given set to be equal. (Contributed by Thierry Arnoux, 28-Dec-2021.)

Assertion

Ref	Expression
difininv	⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐴 ∩ 𝐵) = (𝐶 ∩ 𝐵))

Proof of Theorem difininv

Step	Hyp	Ref	Expression
1		indif1 4288	. . . . . 6 ⊢ ((𝐴 ∖ 𝐶) ∩ 𝐵) = ((𝐴 ∩ 𝐵) ∖ 𝐶)
2	1	eqeq1i 2740	. . . . 5 ⊢ (((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ↔ ((𝐴 ∩ 𝐵) ∖ 𝐶) = ∅)
3		ssdif0 4372	. . . . 5 ⊢ ((𝐴 ∩ 𝐵) ⊆ 𝐶 ↔ ((𝐴 ∩ 𝐵) ∖ 𝐶) = ∅)
4	2, 3	sylbb2 238	. . . 4 ⊢ (((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ → (𝐴 ∩ 𝐵) ⊆ 𝐶)
5	4	adantr 480	. . 3 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐴 ∩ 𝐵) ⊆ 𝐶)
6		inss2 4246	. . . 4 ⊢ (𝐴 ∩ 𝐵) ⊆ 𝐵
7	6	a1i 11	. . 3 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐴 ∩ 𝐵) ⊆ 𝐵)
8	5, 7	ssind 4249	. 2 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐴 ∩ 𝐵) ⊆ (𝐶 ∩ 𝐵))
9		indif1 4288	. . . . . 6 ⊢ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ((𝐶 ∩ 𝐵) ∖ 𝐴)
10	9	eqeq1i 2740	. . . . 5 ⊢ (((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅ ↔ ((𝐶 ∩ 𝐵) ∖ 𝐴) = ∅)
11		ssdif0 4372	. . . . 5 ⊢ ((𝐶 ∩ 𝐵) ⊆ 𝐴 ↔ ((𝐶 ∩ 𝐵) ∖ 𝐴) = ∅)
12	10, 11	sylbb2 238	. . . 4 ⊢ (((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅ → (𝐶 ∩ 𝐵) ⊆ 𝐴)
13	12	adantl 481	. . 3 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐶 ∩ 𝐵) ⊆ 𝐴)
14		inss2 4246	. . . 4 ⊢ (𝐶 ∩ 𝐵) ⊆ 𝐵
15	14	a1i 11	. . 3 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐶 ∩ 𝐵) ⊆ 𝐵)
16	13, 15	ssind 4249	. 2 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐶 ∩ 𝐵) ⊆ (𝐴 ∩ 𝐵))
17	8, 16	eqssd 4013	1 ⊢ ((((𝐴 ∖ 𝐶) ∩ 𝐵) = ∅ ∧ ((𝐶 ∖ 𝐴) ∩ 𝐵) = ∅) → (𝐴 ∩ 𝐵) = (𝐶 ∩ 𝐵))

Syntax hints:   → wi 4   ∧ wa 395   = wceq 1537   ∖ cdif 3960   ∩ cin 3962   ⊆ wss 3963  ∅c0 4339

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-8 2108  ax-9 2116  ax-ext 2706

This theorem depends on definitions:  df-bi 207  df-an 396  df-tru 1540  df-fal 1550  df-ex 1777  df-sb 2063  df-clab 2713  df-cleq 2727  df-clel 2814  df-rab 3434  df-v 3480  df-dif 3966  df-in 3970  df-ss 3980  df-nul 4340

This theorem is referenced by:  chtvalz  34623