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Theorem itgss 25320

Description: Expand the set of an integral by adding zeroes outside the domain. (Contributed by Mario Carneiro, 11-Aug-2014.) (Revised by Mario Carneiro, 23-Aug-2014.)

**Hypotheses**
Ref	Expression
itgss.1	⊢ (𝜑 → 𝐴 ⊆ 𝐵)
itgss.2	⊢ ((𝜑 ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → 𝐶 = 0)

**Assertion**
Ref	Expression
itgss	⊢ (𝜑 → ∫𝐴𝐶 d𝑥 = ∫𝐵𝐶 d𝑥)

Distinct variable group: 𝜑,𝑥 Allowed substitution hints: 𝐴(𝑥) 𝐵(𝑥) 𝐶(𝑥)

Proof of Theorem itgss Dummy variable 𝑘 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		elfzelz 13497	. . . 4 ⊢ (𝑘 ∈ (0...3) → 𝑘 ∈ ℤ)
2		iffalse 4536	. . . . . . . . . . . . . 14 ⊢ (¬ 𝑥 ∈ 𝐴 → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = 0)
3	2	ad2antll 727	. . . . . . . . . . . . 13 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐴)) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = 0)
4		eldif 3957	. . . . . . . . . . . . . 14 ⊢ (𝑥 ∈ (𝐵 ∖ 𝐴) ↔ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐴))
5		itgss.2	. . . . . . . . . . . . . . . . . . . . 21 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → 𝐶 = 0)
6	5	adantlr 713	. . . . . . . . . . . . . . . . . . . 20 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → 𝐶 = 0)
7	6	oveq1d 7420	. . . . . . . . . . . . . . . . . . 19 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → (𝐶 / (i↑𝑘)) = (0 / (i↑𝑘)))
8		ax-icn 11165	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ i ∈ ℂ
9		ine0 11645	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ i ≠ 0
10		expclz 14046	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ ((i ∈ ℂ ∧ i ≠ 0 ∧ 𝑘 ∈ ℤ) → (i↑𝑘) ∈ ℂ)
11	8, 9, 10	mp3an12 1451	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑘 ∈ ℤ → (i↑𝑘) ∈ ℂ)
12		expne0i 14056	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ ((i ∈ ℂ ∧ i ≠ 0 ∧ 𝑘 ∈ ℤ) → (i↑𝑘) ≠ 0)
13	8, 9, 12	mp3an12 1451	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑘 ∈ ℤ → (i↑𝑘) ≠ 0)
14	11, 13	div0d 11985	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑘 ∈ ℤ → (0 / (i↑𝑘)) = 0)
15	14	ad2antlr 725	. . . . . . . . . . . . . . . . . . 19 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → (0 / (i↑𝑘)) = 0)
16	7, 15	eqtrd 2772	. . . . . . . . . . . . . . . . . 18 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → (𝐶 / (i↑𝑘)) = 0)
17	16	fveq2d 6892	. . . . . . . . . . . . . . . . 17 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → (ℜ‘(𝐶 / (i↑𝑘))) = (ℜ‘0))
18		re0 15095	. . . . . . . . . . . . . . . . 17 ⊢ (ℜ‘0) = 0
19	17, 18	eqtrdi 2788	. . . . . . . . . . . . . . . 16 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → (ℜ‘(𝐶 / (i↑𝑘))) = 0)
20	19	ifeq1d 4546	. . . . . . . . . . . . . . 15 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), 0, 0))
21		ifid 4567	. . . . . . . . . . . . . . 15 ⊢ if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), 0, 0) = 0
22	20, 21	eqtrdi 2788	. . . . . . . . . . . . . 14 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ (𝐵 ∖ 𝐴)) → if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = 0)
23	4, 22	sylan2br 595	. . . . . . . . . . . . 13 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐴)) → if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = 0)
24	3, 23	eqtr4d 2775	. . . . . . . . . . . 12 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ (𝑥 ∈ 𝐵 ∧ ¬ 𝑥 ∈ 𝐴)) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
25	24	expr 457	. . . . . . . . . . 11 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ 𝐵) → (¬ 𝑥 ∈ 𝐴 → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))
26		iftrue 4533	. . . . . . . . . . 11 ⊢ (𝑥 ∈ 𝐴 → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
27	25, 26	pm2.61d2 181	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
28		iftrue 4533	. . . . . . . . . . 11 ⊢ (𝑥 ∈ 𝐵 → if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
29	28	adantl 482	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
30	27, 29	eqtr4d 2775	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0))
31		itgss.1	. . . . . . . . . . . . . 14 ⊢ (𝜑 → 𝐴 ⊆ 𝐵)
32	31	adantr 481	. . . . . . . . . . . . 13 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → 𝐴 ⊆ 𝐵)
33	32	sseld 3980	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → (𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵))
34	33	con3dimp 409	. . . . . . . . . . 11 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ ¬ 𝑥 ∈ 𝐵) → ¬ 𝑥 ∈ 𝐴)
35	34, 2	syl 17	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ ¬ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = 0)
36		iffalse 4536	. . . . . . . . . . 11 ⊢ (¬ 𝑥 ∈ 𝐵 → if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = 0)
37	36	adantl 482	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ ¬ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = 0)
38	35, 37	eqtr4d 2775	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝑘 ∈ ℤ) ∧ ¬ 𝑥 ∈ 𝐵) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0))
39	30, 38	pm2.61dan 811	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0) = if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0))
40		ifan 4580	. . . . . . . 8 ⊢ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = if(𝑥 ∈ 𝐴, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0)
41		ifan 4580	. . . . . . . 8 ⊢ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = if(𝑥 ∈ 𝐵, if(0 ≤ (ℜ‘(𝐶 / (i↑𝑘))), (ℜ‘(𝐶 / (i↑𝑘))), 0), 0)
42	39, 40, 41	3eqtr4g 2797	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0) = if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0))
43	42	mpteq2dv 5249	. . . . . 6 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → (𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)) = (𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))
44	43	fveq2d 6892	. . . . 5 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0))) = (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0))))
45	44	oveq2d 7421	. . . 4 ⊢ ((𝜑 ∧ 𝑘 ∈ ℤ) → ((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))) = ((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))))
46	1, 45	sylan2 593	. . 3 ⊢ ((𝜑 ∧ 𝑘 ∈ (0...3)) → ((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))) = ((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))))
47	46	sumeq2dv 15645	. 2 ⊢ (𝜑 → Σ𝑘 ∈ (0...3)((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))) = Σ𝑘 ∈ (0...3)((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0)))))
48		eqid 2732	. . 3 ⊢ (ℜ‘(𝐶 / (i↑𝑘))) = (ℜ‘(𝐶 / (i↑𝑘)))
49	48	dfitg 25278	. 2 ⊢ ∫𝐴𝐶 d𝑥 = Σ𝑘 ∈ (0...3)((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐴 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0))))
50	48	dfitg 25278	. 2 ⊢ ∫𝐵𝐶 d𝑥 = Σ𝑘 ∈ (0...3)((i↑𝑘) · (∫₂‘(𝑥 ∈ ℝ ↦ if((𝑥 ∈ 𝐵 ∧ 0 ≤ (ℜ‘(𝐶 / (i↑𝑘)))), (ℜ‘(𝐶 / (i↑𝑘))), 0))))
51	47, 49, 50	3eqtr4g 2797	1 ⊢ (𝜑 → ∫𝐴𝐶 d𝑥 = ∫𝐵𝐶 d𝑥)

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 → wi 4 ∧ wa 396 = wceq 1541 ∈ wcel 2106 ≠ wne 2940 ∖ cdif 3944 ⊆ wss 3947 ifcif 4527 class class class wbr 5147 ↦ cmpt 5230 ‘cfv 6540 (class class class)co 7405 ℂcc 11104 ℝcr 11105 0cc0 11106 ici 11108 · cmul 11111 ≤ cle 11245 / cdiv 11867 3c3 12264 ℤcz 12554 ...cfz 13480 ↑cexp 14023 ℜcre 15040 Σcsu 15628 ∫₂citg2 25124 ∫citg 25126

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2703 ax-sep 5298 ax-nul 5305 ax-pow 5362 ax-pr 5426 ax-un 7721 ax-cnex 11162 ax-resscn 11163 ax-1cn 11164 ax-icn 11165 ax-addcl 11166 ax-addrcl 11167 ax-mulcl 11168 ax-mulrcl 11169 ax-mulcom 11170 ax-addass 11171 ax-mulass 11172 ax-distr 11173 ax-i2m1 11174 ax-1ne0 11175 ax-1rid 11176 ax-rnegex 11177 ax-rrecex 11178 ax-cnre 11179 ax-pre-lttri 11180 ax-pre-lttrn 11181 ax-pre-ltadd 11182 ax-pre-mulgt0 11183

This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2534 df-eu 2563 df-clab 2710 df-cleq 2724 df-clel 2810 df-nfc 2885 df-ne 2941 df-nel 3047 df-ral 3062 df-rex 3071 df-rmo 3376 df-reu 3377 df-rab 3433 df-v 3476 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3966 df-nul 4322 df-if 4528 df-pw 4603 df-sn 4628 df-pr 4630 df-op 4634 df-uni 4908 df-iun 4998 df-br 5148 df-opab 5210 df-mpt 5231 df-tr 5265 df-id 5573 df-eprel 5579 df-po 5587 df-so 5588 df-fr 5630 df-we 5632 df-xp 5681 df-rel 5682 df-cnv 5683 df-co 5684 df-dm 5685 df-rn 5686 df-res 5687 df-ima 5688 df-pred 6297 df-ord 6364 df-on 6365 df-lim 6366 df-suc 6367 df-iota 6492 df-fun 6542 df-fn 6543 df-f 6544 df-f1 6545 df-fo 6546 df-f1o 6547 df-fv 6548 df-riota 7361 df-ov 7408 df-oprab 7409 df-mpo 7410 df-om 7852 df-1st 7971 df-2nd 7972 df-frecs 8262 df-wrecs 8293 df-recs 8367 df-rdg 8406 df-er 8699 df-en 8936 df-dom 8937 df-sdom 8938 df-pnf 11246 df-mnf 11247 df-xr 11248 df-ltxr 11249 df-le 11250 df-sub 11442 df-neg 11443 df-div 11868 df-nn 12209 df-2 12271 df-n0 12469 df-z 12555 df-uz 12819 df-fz 13481 df-seq 13963 df-exp 14024 df-cj 15042 df-re 15043 df-im 15044 df-sum 15629 df-itg 25131

This theorem is referenced by: itgss2 25321 areacirc 36569

W3C validator