fourierdlem10 - Mathbox for Glauco Siliprandi

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Theorem fourierdlem10 46889

Description: Condition on the bounds of a nonempty subinterval. (Contributed by Glauco Siliprandi, 11-Dec-2019.)

**Hypotheses**
Ref	Expression
fourierdlem10.1	⊢ (𝜑 → 𝐴 ∈ ℝ)
fourierdlem10.2	⊢ (𝜑 → 𝐵 ∈ ℝ)
fourierdlem10.3	⊢ (𝜑 → 𝐶 ∈ ℝ)
fourierdlem10.4	⊢ (𝜑 → 𝐷 ∈ ℝ)
fourierdlem10.5	⊢ (𝜑 → 𝐶 < 𝐷)
fourierdlem10.6	⊢ (𝜑 → (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))

**Assertion**
Ref	Expression
fourierdlem10	⊢ (𝜑 → (𝐴 ≤ 𝐶 ∧ 𝐷 ≤ 𝐵))

**Proof of Theorem fourierdlem10**
Step	Hyp	Ref	Expression
1		fourierdlem10.1	. . 3 ⊢ (𝜑 → 𝐴 ∈ ℝ)
2		fourierdlem10.3	. . 3 ⊢ (𝜑 → 𝐶 ∈ ℝ)
3		fourierdlem10.6	. . . . 5 ⊢ (𝜑 → (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
4	3	adantr 486	. . . 4 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
5	2	rexrd 11274	. . . . . . 7 ⊢ (𝜑 → 𝐶 ∈ ℝ^*)
6	5	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐶 ∈ ℝ^*)
7		fourierdlem10.4	. . . . . . . 8 ⊢ (𝜑 → 𝐷 ∈ ℝ)
8	7	rexrd 11274	. . . . . . 7 ⊢ (𝜑 → 𝐷 ∈ ℝ^*)
9	8	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐷 ∈ ℝ^*)
10	2, 1	readdcld 11253	. . . . . . . . 9 ⊢ (𝜑 → (𝐶 + 𝐴) ∈ ℝ)
11	10	rehalfcld 12506	. . . . . . . 8 ⊢ (𝜑 → ((𝐶 + 𝐴) / 2) ∈ ℝ)
12	2, 7	readdcld 11253	. . . . . . . . 9 ⊢ (𝜑 → (𝐶 + 𝐷) ∈ ℝ)
13	12	rehalfcld 12506	. . . . . . . 8 ⊢ (𝜑 → ((𝐶 + 𝐷) / 2) ∈ ℝ)
14	11, 13	ifcld 4536	. . . . . . 7 ⊢ (𝜑 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
15	14	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
16		simplr 781	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → 𝐶 < 𝐴)
17	2	ad2antrr 739	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → 𝐶 ∈ ℝ)
18	1	ad2antrr 739	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → 𝐴 ∈ ℝ)
19		avglt1 12497	. . . . . . . . . 10 ⊢ ((𝐶 ∈ ℝ ∧ 𝐴 ∈ ℝ) → (𝐶 < 𝐴 ↔ 𝐶 < ((𝐶 + 𝐴) / 2)))
20	17, 18, 19	syl2anc 596	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → (𝐶 < 𝐴 ↔ 𝐶 < ((𝐶 + 𝐴) / 2)))
21	16, 20	mpbid 235	. . . . . . . 8 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → 𝐶 < ((𝐶 + 𝐴) / 2))
22		iftrue 4495	. . . . . . . . 9 ⊢ (𝐴 ≤ 𝐷 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐴) / 2))
23	22	adantl 487	. . . . . . . 8 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐴) / 2))
24	21, 23	breqtrrd 5141	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ 𝐴 ≤ 𝐷) → 𝐶 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
25		fourierdlem10.5	. . . . . . . . . . 11 ⊢ (𝜑 → 𝐶 < 𝐷)
26	25	adantr 486	. . . . . . . . . 10 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐶 < 𝐷)
27	2	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐶 ∈ ℝ)
28	7	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐷 ∈ ℝ)
29		avglt1 12497	. . . . . . . . . . 11 ⊢ ((𝐶 ∈ ℝ ∧ 𝐷 ∈ ℝ) → (𝐶 < 𝐷 ↔ 𝐶 < ((𝐶 + 𝐷) / 2)))
30	27, 28, 29	syl2anc 596	. . . . . . . . . 10 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → (𝐶 < 𝐷 ↔ 𝐶 < ((𝐶 + 𝐷) / 2)))
31	26, 30	mpbid 235	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐶 < ((𝐶 + 𝐷) / 2))
32		iffalse 4498	. . . . . . . . . . 11 ⊢ (¬ 𝐴 ≤ 𝐷 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐷) / 2))
33	32	eqcomd 2771	. . . . . . . . . 10 ⊢ (¬ 𝐴 ≤ 𝐷 → ((𝐶 + 𝐷) / 2) = if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
34	33	adantl 487	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → ((𝐶 + 𝐷) / 2) = if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
35	31, 34	breqtrd 5139	. . . . . . . 8 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐶 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
36	35	adantlr 728	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐶 < 𝐴) ∧ ¬ 𝐴 ≤ 𝐷) → 𝐶 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
37	24, 36	pm2.61dan 825	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐶 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
38	22	adantl 487	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐴) / 2))
39	10	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → (𝐶 + 𝐴) ∈ ℝ)
40	12	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → (𝐶 + 𝐷) ∈ ℝ)
41		2rp 13037	. . . . . . . . . . . 12 ⊢ 2 ∈ ℝ⁺
42	41	a1i 11	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → 2 ∈ ℝ⁺)
43	1	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → 𝐴 ∈ ℝ)
44	7	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → 𝐷 ∈ ℝ)
45	2	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → 𝐶 ∈ ℝ)
46		simpr 490	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → 𝐴 ≤ 𝐷)
47	43, 44, 45, 46	leadd2dd 11844	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → (𝐶 + 𝐴) ≤ (𝐶 + 𝐷))
48	39, 40, 42, 47	lediv1dd 13134	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → ((𝐶 + 𝐴) / 2) ≤ ((𝐶 + 𝐷) / 2))
49	38, 48	eqbrtrd 5135	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐷) / 2))
50	32	adantl 487	. . . . . . . . . 10 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐷) / 2))
51	13	leidd 11795	. . . . . . . . . . 11 ⊢ (𝜑 → ((𝐶 + 𝐷) / 2) ≤ ((𝐶 + 𝐷) / 2))
52	51	adantr 486	. . . . . . . . . 10 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → ((𝐶 + 𝐷) / 2) ≤ ((𝐶 + 𝐷) / 2))
53	50, 52	eqbrtrd 5135	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐷) / 2))
54	49, 53	pm2.61dan 825	. . . . . . . 8 ⊢ (𝜑 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐷) / 2))
55		avglt2 12498	. . . . . . . . . 10 ⊢ ((𝐶 ∈ ℝ ∧ 𝐷 ∈ ℝ) → (𝐶 < 𝐷 ↔ ((𝐶 + 𝐷) / 2) < 𝐷))
56	2, 7, 55	syl2anc 596	. . . . . . . . 9 ⊢ (𝜑 → (𝐶 < 𝐷 ↔ ((𝐶 + 𝐷) / 2) < 𝐷))
57	25, 56	mpbid 235	. . . . . . . 8 ⊢ (𝜑 → ((𝐶 + 𝐷) / 2) < 𝐷)
58	14, 13, 7, 54, 57	lelttrd 11383	. . . . . . 7 ⊢ (𝜑 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
59	58	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
60	6, 9, 15, 37, 59	eliood 46272	. . . . 5 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐶(,)𝐷))
61	1	adantr 486	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐴 ∈ ℝ)
62	11	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ((𝐶 + 𝐴) / 2) ∈ ℝ)
63	14	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
64	63, 38	eqled 11328	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐴) / 2))
65	14	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
66	11	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → ((𝐶 + 𝐴) / 2) ∈ ℝ)
67		simpr 490	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → ¬ 𝐴 ≤ 𝐷)
68	1	adantr 486	. . . . . . . . . . . . . . . 16 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐴 ∈ ℝ)
69	28, 68	ltnled 11372	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → (𝐷 < 𝐴 ↔ ¬ 𝐴 ≤ 𝐷))
70	67, 69	mpbird 260	. . . . . . . . . . . . . 14 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → 𝐷 < 𝐴)
71	12	adantr 486	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → (𝐶 + 𝐷) ∈ ℝ)
72	10	adantr 486	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → (𝐶 + 𝐴) ∈ ℝ)
73	41	a1i 11	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → 2 ∈ ℝ⁺)
74	7	adantr 486	. . . . . . . . . . . . . . . 16 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → 𝐷 ∈ ℝ)
75	1	adantr 486	. . . . . . . . . . . . . . . 16 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → 𝐴 ∈ ℝ)
76	2	adantr 486	. . . . . . . . . . . . . . . 16 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → 𝐶 ∈ ℝ)
77		simpr 490	. . . . . . . . . . . . . . . 16 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → 𝐷 < 𝐴)
78	74, 75, 76, 77	ltadd2dd 11384	. . . . . . . . . . . . . . 15 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → (𝐶 + 𝐷) < (𝐶 + 𝐴))
79	71, 72, 73, 78	ltdiv1dd 13133	. . . . . . . . . . . . . 14 ⊢ ((𝜑 ∧ 𝐷 < 𝐴) → ((𝐶 + 𝐷) / 2) < ((𝐶 + 𝐴) / 2))
80	70, 79	syldan 603	. . . . . . . . . . . . 13 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → ((𝐶 + 𝐷) / 2) < ((𝐶 + 𝐴) / 2))
81	50, 80	eqbrtrd 5135	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < ((𝐶 + 𝐴) / 2))
82	65, 66, 81	ltled 11373	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ ¬ 𝐴 ≤ 𝐷) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐴) / 2))
83	64, 82	pm2.61dan 825	. . . . . . . . . 10 ⊢ (𝜑 → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐴) / 2))
84	83	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ≤ ((𝐶 + 𝐴) / 2))
85		simpr 490	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐶 < 𝐴)
86	2	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐶 ∈ ℝ)
87		avglt2 12498	. . . . . . . . . . 11 ⊢ ((𝐶 ∈ ℝ ∧ 𝐴 ∈ ℝ) → (𝐶 < 𝐴 ↔ ((𝐶 + 𝐴) / 2) < 𝐴))
88	86, 61, 87	syl2anc 596	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → (𝐶 < 𝐴 ↔ ((𝐶 + 𝐴) / 2) < 𝐴))
89	85, 88	mpbid 235	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ((𝐶 + 𝐴) / 2) < 𝐴)
90	15, 62, 61, 84, 89	lelttrd 11383	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐴)
91	15, 61, 90	ltnsymd 11374	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ¬ 𝐴 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)))
92	91	intn3an2d 1511	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ¬ (if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵))
93	1	rexrd 11274	. . . . . . . 8 ⊢ (𝜑 → 𝐴 ∈ ℝ^*)
94	93	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐴 ∈ ℝ^*)
95		fourierdlem10.2	. . . . . . . . 9 ⊢ (𝜑 → 𝐵 ∈ ℝ)
96	95	rexrd 11274	. . . . . . . 8 ⊢ (𝜑 → 𝐵 ∈ ℝ^*)
97	96	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → 𝐵 ∈ ℝ^*)
98		elioo2 13429	. . . . . . 7 ⊢ ((𝐴 ∈ ℝ^* ∧ 𝐵 ∈ ℝ^*) → (if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵) ↔ (if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵)))
99	94, 97, 98	syl2anc 596	. . . . . 6 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → (if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵) ↔ (if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵)))
100	92, 99	mtbird 328	. . . . 5 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ¬ if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵))
101		nelss 4004	. . . . 5 ⊢ ((if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐶(,)𝐷) ∧ ¬ if(𝐴 ≤ 𝐷, ((𝐶 + 𝐴) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵)) → ¬ (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
102	60, 100, 101	syl2anc 596	. . . 4 ⊢ ((𝜑 ∧ 𝐶 < 𝐴) → ¬ (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
103	4, 102	pm2.65da 829	. . 3 ⊢ (𝜑 → ¬ 𝐶 < 𝐴)
104	1, 2, 103	nltled 11375	. 2 ⊢ (𝜑 → 𝐴 ≤ 𝐶)
105	3	adantr 486	. . . 4 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
106	5	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐶 ∈ ℝ^*)
107	8	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐷 ∈ ℝ^*)
108	95, 7	readdcld 11253	. . . . . . . . 9 ⊢ (𝜑 → (𝐵 + 𝐷) ∈ ℝ)
109	108	rehalfcld 12506	. . . . . . . 8 ⊢ (𝜑 → ((𝐵 + 𝐷) / 2) ∈ ℝ)
110	109, 13	ifcld 4536	. . . . . . 7 ⊢ (𝜑 → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
111	110	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
112	2	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐶 ∈ ℝ)
113	13	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) ∈ ℝ)
114	110	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ)
115	2, 7, 29	syl2anc 596	. . . . . . . . . . 11 ⊢ (𝜑 → (𝐶 < 𝐷 ↔ 𝐶 < ((𝐶 + 𝐷) / 2)))
116	25, 115	mpbid 235	. . . . . . . . . 10 ⊢ (𝜑 → 𝐶 < ((𝐶 + 𝐷) / 2))
117	116	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐶 < ((𝐶 + 𝐷) / 2))
118	12	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → (𝐶 + 𝐷) ∈ ℝ)
119	108	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → (𝐵 + 𝐷) ∈ ℝ)
120	41	a1i 11	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 2 ∈ ℝ⁺)
121	95	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐵 ∈ ℝ)
122	7	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐷 ∈ ℝ)
123		simpr 490	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐶 ≤ 𝐵)
124	112, 121, 122, 123	leadd1dd 11843	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → (𝐶 + 𝐷) ≤ (𝐵 + 𝐷))
125	118, 119, 120, 124	lediv1dd 13134	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) ≤ ((𝐵 + 𝐷) / 2))
126		iftrue 4495	. . . . . . . . . . 11 ⊢ (𝐶 ≤ 𝐵 → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐵 + 𝐷) / 2))
127	126	adantl 487	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐵 + 𝐷) / 2))
128	125, 127	breqtrrd 5141	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) ≤ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
129	112, 113, 114, 117, 128	ltletrd 11385	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝐶 ≤ 𝐵) → 𝐶 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
130	116	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐶 < ((𝐶 + 𝐷) / 2))
131		iffalse 4498	. . . . . . . . . . 11 ⊢ (¬ 𝐶 ≤ 𝐵 → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐷) / 2))
132	131	eqcomd 2771	. . . . . . . . . 10 ⊢ (¬ 𝐶 ≤ 𝐵 → ((𝐶 + 𝐷) / 2) = if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
133	132	adantl 487	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) = if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
134	130, 133	breqtrd 5139	. . . . . . . 8 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐶 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
135	129, 134	pm2.61dan 825	. . . . . . 7 ⊢ (𝜑 → 𝐶 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
136	135	adantr 486	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐶 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
137	126	adantl 487	. . . . . . . 8 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐵 + 𝐷) / 2))
138		simpr 490	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 < 𝐷)
139	95	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 ∈ ℝ)
140	7	adantr 486	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐷 ∈ ℝ)
141		avglt2 12498	. . . . . . . . . . 11 ⊢ ((𝐵 ∈ ℝ ∧ 𝐷 ∈ ℝ) → (𝐵 < 𝐷 ↔ ((𝐵 + 𝐷) / 2) < 𝐷))
142	139, 140, 141	syl2anc 596	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → (𝐵 < 𝐷 ↔ ((𝐵 + 𝐷) / 2) < 𝐷))
143	138, 142	mpbid 235	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ((𝐵 + 𝐷) / 2) < 𝐷)
144	143	adantr 486	. . . . . . . 8 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ 𝐶 ≤ 𝐵) → ((𝐵 + 𝐷) / 2) < 𝐷)
145	137, 144	eqbrtrd 5135	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
146	131	adantl 487	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) = ((𝐶 + 𝐷) / 2))
147	57	adantr 486	. . . . . . . . 9 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) < 𝐷)
148	146, 147	eqbrtrd 5135	. . . . . . . 8 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
149	148	adantlr 728	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ ¬ 𝐶 ≤ 𝐵) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
150	145, 149	pm2.61dan 825	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐷)
151	106, 107, 111, 136, 150	eliood 46272	. . . . 5 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐶(,)𝐷))
152	109	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ((𝐵 + 𝐷) / 2) ∈ ℝ)
153		avglt1 12497	. . . . . . . . . . . . . 14 ⊢ ((𝐵 ∈ ℝ ∧ 𝐷 ∈ ℝ) → (𝐵 < 𝐷 ↔ 𝐵 < ((𝐵 + 𝐷) / 2)))
154	139, 140, 153	syl2anc 596	. . . . . . . . . . . . 13 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → (𝐵 < 𝐷 ↔ 𝐵 < ((𝐵 + 𝐷) / 2)))
155	138, 154	mpbid 235	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 < ((𝐵 + 𝐷) / 2))
156	139, 152, 155	ltled 11373	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 ≤ ((𝐵 + 𝐷) / 2))
157	156	adantr 486	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ 𝐶 ≤ 𝐵) → 𝐵 ≤ ((𝐵 + 𝐷) / 2))
158	157, 137	breqtrrd 5141	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ 𝐶 ≤ 𝐵) → 𝐵 ≤ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
159	95	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 ∈ ℝ)
160	13	adantr 486	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → ((𝐶 + 𝐷) / 2) ∈ ℝ)
161	2	adantr 486	. . . . . . . . . . . . 13 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐶 ∈ ℝ)
162		simpr 490	. . . . . . . . . . . . . 14 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → ¬ 𝐶 ≤ 𝐵)
163	159, 161	ltnled 11372	. . . . . . . . . . . . . 14 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → (𝐵 < 𝐶 ↔ ¬ 𝐶 ≤ 𝐵))
164	162, 163	mpbird 260	. . . . . . . . . . . . 13 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 < 𝐶)
165	159, 161, 160, 164, 130	lttrd 11386	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 < ((𝐶 + 𝐷) / 2))
166	159, 160, 165	ltled 11373	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 ≤ ((𝐶 + 𝐷) / 2))
167	166, 133	breqtrd 5139	. . . . . . . . . 10 ⊢ ((𝜑 ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 ≤ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
168	167	adantlr 728	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝐵 < 𝐷) ∧ ¬ 𝐶 ≤ 𝐵) → 𝐵 ≤ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
169	158, 168	pm2.61dan 825	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 ≤ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)))
170	139, 111, 169	lensymd 11376	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ¬ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵)
171	170	intn3an3d 1512	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ¬ (if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵))
172	93	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐴 ∈ ℝ^*)
173	96	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → 𝐵 ∈ ℝ^*)
174		elioo2 13429	. . . . . . 7 ⊢ ((𝐴 ∈ ℝ^* ∧ 𝐵 ∈ ℝ^*) → (if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵) ↔ (if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵)))
175	172, 173, 174	syl2anc 596	. . . . . 6 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → (if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵) ↔ (if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ ℝ ∧ 𝐴 < if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∧ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) < 𝐵)))
176	171, 175	mtbird 328	. . . . 5 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ¬ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵))
177		nelss 4004	. . . . 5 ⊢ ((if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐶(,)𝐷) ∧ ¬ if(𝐶 ≤ 𝐵, ((𝐵 + 𝐷) / 2), ((𝐶 + 𝐷) / 2)) ∈ (𝐴(,)𝐵)) → ¬ (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
178	151, 176, 177	syl2anc 596	. . . 4 ⊢ ((𝜑 ∧ 𝐵 < 𝐷) → ¬ (𝐶(,)𝐷) ⊆ (𝐴(,)𝐵))
179	105, 178	pm2.65da 829	. . 3 ⊢ (𝜑 → ¬ 𝐵 < 𝐷)
180	7, 95, 179	nltled 11375	. 2 ⊢ (𝜑 → 𝐷 ≤ 𝐵)
181	104, 180	jca 521	1 ⊢ (𝜑 → (𝐴 ≤ 𝐶 ∧ 𝐷 ≤ 𝐵))

Colors of variables: wff setvar class

This proof depends on syntax axioms: ¬ wn 3 → wi 4 ↔ wb 209 ∧ wa 401 ∧ w3a 1103 = wceq 1570 ∈ wcel 2146 ⊆ wss 3906 ifcif 4489 class class class wbr 5111 (class class class)co 7419 ℝcr 11114 + caddc 11118 ℝ^*cxr 11257 < clt 11258 ≤ cle 11259 / cdiv 11886 2c2 12310 ℝ⁺crp 13032 (,)cioo 13388

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1828 ax-4 1842 ax-5 1943 ax-6 2000 ax-7 2041 ax-8 2148 ax-9 2156 ax-10 2179 ax-11 2195 ax-12 2216 ax-ext 2737 ax-sep 5259 ax-nul 5271 ax-pow 5338 ax-pr 5406 ax-un 7742 ax-cnex 11171 ax-resscn 11172 ax-1cn 11173 ax-icn 11174 ax-addcl 11175 ax-addrcl 11176 ax-mulcl 11177 ax-mulrcl 11178 ax-mulcom 11179 ax-addass 11180 ax-mulass 11181 ax-distr 11182 ax-i2m1 11183 ax-1ne0 11184 ax-1rid 11185 ax-rnegex 11186 ax-rrecex 11187 ax-cnre 11188 ax-pre-lttri 11189 ax-pre-lttrn 11190 ax-pre-ltadd 11191 ax-pre-mulgt0 11192

This proof depends on definitions: df-bi 210 df-an 402 df-or 862 df-3or 1104 df-3an 1105 df-tru 1573 df-fal 1583 df-ex 1813 df-nf 1817 df-sb 2100 df-mo 2569 df-eu 2599 df-clab 2744 df-cleq 2757 df-clel 2840 df-nfc 2914 df-ne 2961 df-nel 3067 df-ral 3082 df-rex 3092 df-rmo 3371 df-reu 3372 df-rab 3419 df-v 3459 df-sbc 3747 df-csb 3855 df-dif 3909 df-un 3911 df-in 3913 df-ss 3923 df-pss 3926 df-nul 4287 df-if 4490 df-pw 4566 df-sn 4592 df-pr 4594 df-op 4598 df-uni 4875 df-iun 4960 df-br 5112 df-opab 5176 df-mpt 5195 df-tr 5221 df-id 5558 df-eprel 5563 df-po 5571 df-so 5572 df-fr 5616 df-we 5618 df-xp 5669 df-rel 5670 df-cnv 5671 df-co 5672 df-dm 5673 df-rn 5674 df-res 5675 df-ima 5676 df-pred 6306 df-ord 6367 df-on 6368 df-lim 6369 df-suc 6370 df-iota 6496 df-fun 6542 df-fn 6543 df-f 6544 df-f1 6545 df-fo 6546 df-f1o 6547 df-fv 6548 df-riota 7376 df-ov 7422 df-oprab 7423 df-mpo 7424 df-om 7869 df-1st 7992 df-2nd 7993 df-frecs 8284 df-wrecs 8315 df-recs 8364 df-rdg 8403 df-er 8700 df-en 8950 df-dom 8951 df-sdom 8952 df-pnf 11260 df-mnf 11261 df-xr 11262 df-ltxr 11263 df-le 11264 df-sub 11458 df-neg 11459 df-div 11887 df-nn 12249 df-2 12318 df-rp 13033 df-ioo 13392

This theorem is used by: fourierdlem32 46911 fourierdlem33 46912 fourierdlem46 46924 fourierdlem50 46928 fourierdlem72 46950 fourierdlem76 46954 fourierdlem89 46967 fourierdlem91 46969 fourierdlem103 46981 fourierdlem104 46982

W3C validator