Theorem uneqin 4237

Description: Equality of union and intersection implies equality of their arguments. (Contributed by NM, 16-Apr-2006.) (Proof shortened by Andrew Salmon, 26-Jun-2011.)

Assertion

Ref	Expression
uneqin	⊢ ((𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵) ↔ 𝐴 = 𝐵)

Proof of Theorem uneqin

Step	Hyp	Ref	Expression
1		eqimss 3991	. . . 4 ⊢ ((𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵) → (𝐴 ∪ 𝐵) ⊆ (𝐴 ∩ 𝐵))
2		unss 4138	. . . . 5 ⊢ ((𝐴 ⊆ (𝐴 ∩ 𝐵) ∧ 𝐵 ⊆ (𝐴 ∩ 𝐵)) ↔ (𝐴 ∪ 𝐵) ⊆ (𝐴 ∩ 𝐵))
3		ssin 4187	. . . . . . 7 ⊢ ((𝐴 ⊆ 𝐴 ∧ 𝐴 ⊆ 𝐵) ↔ 𝐴 ⊆ (𝐴 ∩ 𝐵))
4		sstr 3941	. . . . . . 7 ⊢ ((𝐴 ⊆ 𝐴 ∧ 𝐴 ⊆ 𝐵) → 𝐴 ⊆ 𝐵)
5	3, 4	sylbir 235	. . . . . 6 ⊢ (𝐴 ⊆ (𝐴 ∩ 𝐵) → 𝐴 ⊆ 𝐵)
6		ssin 4187	. . . . . . 7 ⊢ ((𝐵 ⊆ 𝐴 ∧ 𝐵 ⊆ 𝐵) ↔ 𝐵 ⊆ (𝐴 ∩ 𝐵))
7		simpl 482	. . . . . . 7 ⊢ ((𝐵 ⊆ 𝐴 ∧ 𝐵 ⊆ 𝐵) → 𝐵 ⊆ 𝐴)
8	6, 7	sylbir 235	. . . . . 6 ⊢ (𝐵 ⊆ (𝐴 ∩ 𝐵) → 𝐵 ⊆ 𝐴)
9	5, 8	anim12i 613	. . . . 5 ⊢ ((𝐴 ⊆ (𝐴 ∩ 𝐵) ∧ 𝐵 ⊆ (𝐴 ∩ 𝐵)) → (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴))
10	2, 9	sylbir 235	. . . 4 ⊢ ((𝐴 ∪ 𝐵) ⊆ (𝐴 ∩ 𝐵) → (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴))
11	1, 10	syl 17	. . 3 ⊢ ((𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵) → (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴))
12		eqss 3948	. . 3 ⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴))
13	11, 12	sylibr 234	. 2 ⊢ ((𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵) → 𝐴 = 𝐵)
14		unidm 4105	. . . 4 ⊢ (𝐴 ∪ 𝐴) = 𝐴
15		inidm 4175	. . . 4 ⊢ (𝐴 ∩ 𝐴) = 𝐴
16	14, 15	eqtr4i 2756	. . 3 ⊢ (𝐴 ∪ 𝐴) = (𝐴 ∩ 𝐴)
17		uneq2 4110	. . 3 ⊢ (𝐴 = 𝐵 → (𝐴 ∪ 𝐴) = (𝐴 ∪ 𝐵))
18		ineq2 4162	. . 3 ⊢ (𝐴 = 𝐵 → (𝐴 ∩ 𝐴) = (𝐴 ∩ 𝐵))
19	16, 17, 18	3eqtr3a 2789	. 2 ⊢ (𝐴 = 𝐵 → (𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵))
20	13, 19	impbii 209	1 ⊢ ((𝐴 ∪ 𝐵) = (𝐴 ∩ 𝐵) ↔ 𝐴 = 𝐵)

Syntax hints:   ↔ wb 206   ∧ wa 395   = wceq 1541   ∪ cun 3898   ∩ cin 3899   ⊆ wss 3900

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2112  ax-9 2120  ax-ext 2702

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-tru 1544  df-ex 1781  df-sb 2067  df-clab 2709  df-cleq 2722  df-clel 2804  df-rab 3394  df-v 3436  df-un 3905  df-in 3907  df-ss 3917

This theorem is referenced by:  uniintsn  4933