Theorem iscnrm3rlem1 49667

Description: Lemma for iscnrm3rlem2 49668. The hypothesis could be generalized to (𝜑 → (𝑆 ∖ 𝑇) ⊆ 𝑋). (Contributed by Zhi Wang, 5-Sep-2024.)

Hypothesis

Ref	Expression
iscnrm3rlem1.1	⊢ (𝜑 → 𝑆 ⊆ 𝑋)

Assertion

Ref	Expression
iscnrm3rlem1	⊢ (𝜑 → (𝑆 ∖ 𝑇) = (𝑆 ∩ (𝑋 ∖ (𝑆 ∩ 𝑇))))

Proof of Theorem iscnrm3rlem1

Step	Hyp	Ref	Expression
1		difindi 4253	. . . 4 ⊢ (𝑋 ∖ (𝑆 ∩ 𝑇)) = ((𝑋 ∖ 𝑆) ∪ (𝑋 ∖ 𝑇))
2	1	ineq2i 4178	. . 3 ⊢ (𝑆 ∩ (𝑋 ∖ (𝑆 ∩ 𝑇))) = (𝑆 ∩ ((𝑋 ∖ 𝑆) ∪ (𝑋 ∖ 𝑇)))
3		indi 4245	. . 3 ⊢ (𝑆 ∩ ((𝑋 ∖ 𝑆) ∪ (𝑋 ∖ 𝑇))) = ((𝑆 ∩ (𝑋 ∖ 𝑆)) ∪ (𝑆 ∩ (𝑋 ∖ 𝑇)))
4		disjdif 4438	. . . . 5 ⊢ (𝑆 ∩ (𝑋 ∖ 𝑆)) = ∅
5	4	uneq1i 4126	. . . 4 ⊢ ((𝑆 ∩ (𝑋 ∖ 𝑆)) ∪ (𝑆 ∩ (𝑋 ∖ 𝑇))) = (∅ ∪ (𝑆 ∩ (𝑋 ∖ 𝑇)))
6		0un 4360	. . . 4 ⊢ (∅ ∪ (𝑆 ∩ (𝑋 ∖ 𝑇))) = (𝑆 ∩ (𝑋 ∖ 𝑇))
7		indif2 4242	. . . 4 ⊢ (𝑆 ∩ (𝑋 ∖ 𝑇)) = ((𝑆 ∩ 𝑋) ∖ 𝑇)
8	5, 6, 7	3eqtri 2797	. . 3 ⊢ ((𝑆 ∩ (𝑋 ∖ 𝑆)) ∪ (𝑆 ∩ (𝑋 ∖ 𝑇))) = ((𝑆 ∩ 𝑋) ∖ 𝑇)
9	2, 3, 8	3eqtri 2797	. 2 ⊢ (𝑆 ∩ (𝑋 ∖ (𝑆 ∩ 𝑇))) = ((𝑆 ∩ 𝑋) ∖ 𝑇)
10		iscnrm3rlem1.1	. . . 4 ⊢ (𝜑 → 𝑆 ⊆ 𝑋)
11		dfss2 3931	. . . 4 ⊢ (𝑆 ⊆ 𝑋 ↔ (𝑆 ∩ 𝑋) = 𝑆)
12	10, 11	sylib 221	. . 3 ⊢ (𝜑 → (𝑆 ∩ 𝑋) = 𝑆)
13	12	difeq1d 4088	. 2 ⊢ (𝜑 → ((𝑆 ∩ 𝑋) ∖ 𝑇) = (𝑆 ∖ 𝑇))
14	9, 13	eqtr2id 2818	1 ⊢ (𝜑 → (𝑆 ∖ 𝑇) = (𝑆 ∩ (𝑋 ∖ (𝑆 ∩ 𝑇))))

Syntax hints:   → wi 4   = wceq 1568   ∖ cdif 3910   ∪ cun 3911   ∩ cin 3912   ⊆ wss 3913  ∅c0 4294

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1823  ax-4 1837  ax-5 1938  ax-6 1995  ax-7 2036  ax-8 2152  ax-9 2160  ax-ext 2742

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3an 1103  df-tru 1571  df-fal 1581  df-ex 1808  df-sb 2099  df-clab 2749  df-cleq 2762  df-clel 2845  df-rab 3424  df-v 3464  df-dif 3916  df-un 3918  df-in 3920  df-ss 3930  df-nul 4295

This theorem is referenced by:  iscnrm3rlem2  49668