dveq0 - Metamath Proof Explorer

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Theorem dveq0 24714

Description: If a continuous function has zero derivative at all points on the interior of a closed interval, then it must be a constant function. (Contributed by Mario Carneiro, 2-Sep-2014.) (Proof shortened by Mario Carneiro, 3-Mar-2015.)

**Hypotheses**
Ref	Expression
dveq0.a	⊢ (𝜑 → 𝐴 ∈ ℝ)
dveq0.b	⊢ (𝜑 → 𝐵 ∈ ℝ)
dveq0.c	⊢ (𝜑 → 𝐹 ∈ ((𝐴[,]𝐵)–cn→ℂ))
dveq0.d	⊢ (𝜑 → (ℝ D 𝐹) = ((𝐴(,)𝐵) × {0}))

**Assertion**
Ref	Expression
dveq0	⊢ (𝜑 → 𝐹 = ((𝐴[,]𝐵) × {(𝐹‘𝐴)}))

Proof of Theorem dveq0 Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		dveq0.c	. . . 4 ⊢ (𝜑 → 𝐹 ∈ ((𝐴[,]𝐵)–cn→ℂ))
2		cncff 23609	. . . 4 ⊢ (𝐹 ∈ ((𝐴[,]𝐵)–cn→ℂ) → 𝐹:(𝐴[,]𝐵)⟶ℂ)
3	1, 2	syl 17	. . 3 ⊢ (𝜑 → 𝐹:(𝐴[,]𝐵)⟶ℂ)
4	3	ffnd 6505	. 2 ⊢ (𝜑 → 𝐹 Fn (𝐴[,]𝐵))
5		fvex 6677	. . 3 ⊢ (𝐹‘𝐴) ∈ V
6		fnconstg 6558	. . 3 ⊢ ((𝐹‘𝐴) ∈ V → ((𝐴[,]𝐵) × {(𝐹‘𝐴)}) Fn (𝐴[,]𝐵))
7	5, 6	mp1i 13	. 2 ⊢ (𝜑 → ((𝐴[,]𝐵) × {(𝐹‘𝐴)}) Fn (𝐴[,]𝐵))
8	5	fvconst2 6964	. . . 4 ⊢ (𝑥 ∈ (𝐴[,]𝐵) → (((𝐴[,]𝐵) × {(𝐹‘𝐴)})‘𝑥) = (𝐹‘𝐴))
9	8	adantl 485	. . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (((𝐴[,]𝐵) × {(𝐹‘𝐴)})‘𝑥) = (𝐹‘𝐴))
10	3	adantr 484	. . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐹:(𝐴[,]𝐵)⟶ℂ)
11		dveq0.a	. . . . . . . 8 ⊢ (𝜑 → 𝐴 ∈ ℝ)
12	11	adantr 484	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ∈ ℝ)
13	12	rexrd 10743	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ∈ ℝ^*)
14		dveq0.b	. . . . . . . 8 ⊢ (𝜑 → 𝐵 ∈ ℝ)
15	14	adantr 484	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐵 ∈ ℝ)
16	15	rexrd 10743	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐵 ∈ ℝ^*)
17		elicc2 12858	. . . . . . . . . 10 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝑥 ∈ (𝐴[,]𝐵) ↔ (𝑥 ∈ ℝ ∧ 𝐴 ≤ 𝑥 ∧ 𝑥 ≤ 𝐵)))
18	11, 14, 17	syl2anc 587	. . . . . . . . 9 ⊢ (𝜑 → (𝑥 ∈ (𝐴[,]𝐵) ↔ (𝑥 ∈ ℝ ∧ 𝐴 ≤ 𝑥 ∧ 𝑥 ≤ 𝐵)))
19	18	biimpa 480	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝑥 ∈ ℝ ∧ 𝐴 ≤ 𝑥 ∧ 𝑥 ≤ 𝐵))
20	19	simp1d 1140	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝑥 ∈ ℝ)
21	19	simp2d 1141	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ≤ 𝑥)
22	19	simp3d 1142	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝑥 ≤ 𝐵)
23	12, 20, 15, 21, 22	letrd 10849	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ≤ 𝐵)
24		lbicc2 12910	. . . . . 6 ⊢ ((𝐴 ∈ ℝ^* ∧ 𝐵 ∈ ℝ^* ∧ 𝐴 ≤ 𝐵) → 𝐴 ∈ (𝐴[,]𝐵))
25	13, 16, 23, 24	syl3anc 1369	. . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ∈ (𝐴[,]𝐵))
26	10, 25	ffvelrnd 6850	. . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐹‘𝐴) ∈ ℂ)
27	3	ffvelrnda 6849	. . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐹‘𝑥) ∈ ℂ)
28	26, 27	subcld 11049	. . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → ((𝐹‘𝐴) − (𝐹‘𝑥)) ∈ ℂ)
29		simpr 488	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝑥 ∈ (𝐴[,]𝐵))
30	25, 29	jca 515	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐴 ∈ (𝐴[,]𝐵) ∧ 𝑥 ∈ (𝐴[,]𝐵)))
31		dveq0.d	. . . . . . . . . . 11 ⊢ (𝜑 → (ℝ D 𝐹) = ((𝐴(,)𝐵) × {0}))
32	31	dmeqd 5752	. . . . . . . . . 10 ⊢ (𝜑 → dom (ℝ D 𝐹) = dom ((𝐴(,)𝐵) × {0}))
33		c0ex 10687	. . . . . . . . . . . 12 ⊢ 0 ∈ V
34	33	snnz 4673	. . . . . . . . . . 11 ⊢ {0} ≠ ∅
35		dmxp 5776	. . . . . . . . . . 11 ⊢ ({0} ≠ ∅ → dom ((𝐴(,)𝐵) × {0}) = (𝐴(,)𝐵))
36	34, 35	ax-mp 5	. . . . . . . . . 10 ⊢ dom ((𝐴(,)𝐵) × {0}) = (𝐴(,)𝐵)
37	32, 36	eqtrdi 2810	. . . . . . . . 9 ⊢ (𝜑 → dom (ℝ D 𝐹) = (𝐴(,)𝐵))
38		0red 10696	. . . . . . . . 9 ⊢ (𝜑 → 0 ∈ ℝ)
39	31	fveq1d 6666	. . . . . . . . . . . 12 ⊢ (𝜑 → ((ℝ D 𝐹)‘𝑦) = (((𝐴(,)𝐵) × {0})‘𝑦))
40	33	fvconst2 6964	. . . . . . . . . . . 12 ⊢ (𝑦 ∈ (𝐴(,)𝐵) → (((𝐴(,)𝐵) × {0})‘𝑦) = 0)
41	39, 40	sylan9eq 2814	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝑦 ∈ (𝐴(,)𝐵)) → ((ℝ D 𝐹)‘𝑦) = 0)
42	41	abs00bd 14713	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝑦 ∈ (𝐴(,)𝐵)) → (abs‘((ℝ D 𝐹)‘𝑦)) = 0)
43		0le0 11789	. . . . . . . . . 10 ⊢ 0 ≤ 0
44	42, 43	eqbrtrdi 5076	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝑦 ∈ (𝐴(,)𝐵)) → (abs‘((ℝ D 𝐹)‘𝑦)) ≤ 0)
45	11, 14, 1, 37, 38, 44	dvlip 24707	. . . . . . . 8 ⊢ ((𝜑 ∧ (𝐴 ∈ (𝐴[,]𝐵) ∧ 𝑥 ∈ (𝐴[,]𝐵))) → (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ≤ (0 · (abs‘(𝐴 − 𝑥))))
46	30, 45	syldan 594	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ≤ (0 · (abs‘(𝐴 − 𝑥))))
47	12	recnd 10721	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝐴 ∈ ℂ)
48	20	recnd 10721	. . . . . . . . . . 11 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝑥 ∈ ℂ)
49	47, 48	subcld 11049	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐴 − 𝑥) ∈ ℂ)
50	49	abscld 14858	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘(𝐴 − 𝑥)) ∈ ℝ)
51	50	recnd 10721	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘(𝐴 − 𝑥)) ∈ ℂ)
52	51	mul02d 10890	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (0 · (abs‘(𝐴 − 𝑥))) = 0)
53	46, 52	breqtrd 5063	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ≤ 0)
54	28	absge0d 14866	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 0 ≤ (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))))
55	28	abscld 14858	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ∈ ℝ)
56		0re 10695	. . . . . . 7 ⊢ 0 ∈ ℝ
57		letri3 10778	. . . . . . 7 ⊢ (((abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ∈ ℝ ∧ 0 ∈ ℝ) → ((abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) = 0 ↔ ((abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ≤ 0 ∧ 0 ≤ (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))))))
58	55, 56, 57	sylancl 589	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → ((abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) = 0 ↔ ((abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) ≤ 0 ∧ 0 ≤ (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))))))
59	53, 54, 58	mpbir2and 712	. . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (abs‘((𝐹‘𝐴) − (𝐹‘𝑥))) = 0)
60	28, 59	abs00d 14868	. . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → ((𝐹‘𝐴) − (𝐹‘𝑥)) = 0)
61	26, 27, 60	subeq0d 11057	. . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐹‘𝐴) = (𝐹‘𝑥))
62	9, 61	eqtr2d 2795	. 2 ⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐹‘𝑥) = (((𝐴[,]𝐵) × {(𝐹‘𝐴)})‘𝑥))
63	4, 7, 62	eqfnfvd 6802	1 ⊢ (𝜑 → 𝐹 = ((𝐴[,]𝐵) × {(𝐹‘𝐴)}))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 209 ∧ wa 399 ∧ w3a 1085 = wceq 1539 ∈ wcel 2112 ≠ wne 2952 Vcvv 3410 ∅c0 4228 {csn 4526 class class class wbr 5037 × cxp 5527 dom cdm 5529 Fn wfn 6336 ⟶wf 6337 ‘cfv 6341 (class class class)co 7157 ℂcc 10587 ℝcr 10588 0cc0 10589 · cmul 10594 ℝ^*cxr 10726 ≤ cle 10728 − cmin 10922 (,)cioo 12793 [,]cicc 12796 abscabs 14655 –cn→ccncf 23592 D cdv 24577

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1912 ax-6 1971 ax-7 2016 ax-8 2114 ax-9 2122 ax-10 2143 ax-11 2159 ax-12 2176 ax-ext 2730 ax-rep 5161 ax-sep 5174 ax-nul 5181 ax-pow 5239 ax-pr 5303 ax-un 7466 ax-cnex 10645 ax-resscn 10646 ax-1cn 10647 ax-icn 10648 ax-addcl 10649 ax-addrcl 10650 ax-mulcl 10651 ax-mulrcl 10652 ax-mulcom 10653 ax-addass 10654 ax-mulass 10655 ax-distr 10656 ax-i2m1 10657 ax-1ne0 10658 ax-1rid 10659 ax-rnegex 10660 ax-rrecex 10661 ax-cnre 10662 ax-pre-lttri 10663 ax-pre-lttrn 10664 ax-pre-ltadd 10665 ax-pre-mulgt0 10666 ax-pre-sup 10667 ax-addf 10668 ax-mulf 10669

This theorem depends on definitions: df-bi 210 df-an 400 df-or 845 df-3or 1086 df-3an 1087 df-tru 1542 df-fal 1552 df-ex 1783 df-nf 1787 df-sb 2071 df-mo 2558 df-eu 2589 df-clab 2737 df-cleq 2751 df-clel 2831 df-nfc 2902 df-ne 2953 df-nel 3057 df-ral 3076 df-rex 3077 df-reu 3078 df-rmo 3079 df-rab 3080 df-v 3412 df-sbc 3700 df-csb 3809 df-dif 3864 df-un 3866 df-in 3868 df-ss 3878 df-pss 3880 df-nul 4229 df-if 4425 df-pw 4500 df-sn 4527 df-pr 4529 df-tp 4531 df-op 4533 df-uni 4803 df-int 4843 df-iun 4889 df-iin 4890 df-br 5038 df-opab 5100 df-mpt 5118 df-tr 5144 df-id 5435 df-eprel 5440 df-po 5448 df-so 5449 df-fr 5488 df-se 5489 df-we 5490 df-xp 5535 df-rel 5536 df-cnv 5537 df-co 5538 df-dm 5539 df-rn 5540 df-res 5541 df-ima 5542 df-pred 6132 df-ord 6178 df-on 6179 df-lim 6180 df-suc 6181 df-iota 6300 df-fun 6343 df-fn 6344 df-f 6345 df-f1 6346 df-fo 6347 df-f1o 6348 df-fv 6349 df-isom 6350 df-riota 7115 df-ov 7160 df-oprab 7161 df-mpo 7162 df-of 7412 df-om 7587 df-1st 7700 df-2nd 7701 df-supp 7843 df-wrecs 7964 df-recs 8025 df-rdg 8063 df-1o 8119 df-2o 8120 df-er 8306 df-map 8425 df-pm 8426 df-ixp 8494 df-en 8542 df-dom 8543 df-sdom 8544 df-fin 8545 df-fsupp 8881 df-fi 8922 df-sup 8953 df-inf 8954 df-oi 9021 df-card 9415 df-pnf 10729 df-mnf 10730 df-xr 10731 df-ltxr 10732 df-le 10733 df-sub 10924 df-neg 10925 df-div 11350 df-nn 11689 df-2 11751 df-3 11752 df-4 11753 df-5 11754 df-6 11755 df-7 11756 df-8 11757 df-9 11758 df-n0 11949 df-z 12035 df-dec 12152 df-uz 12297 df-q 12403 df-rp 12445 df-xneg 12562 df-xadd 12563 df-xmul 12564 df-ioo 12797 df-ico 12799 df-icc 12800 df-fz 12954 df-fzo 13097 df-seq 13433 df-exp 13494 df-hash 13755 df-cj 14520 df-re 14521 df-im 14522 df-sqrt 14656 df-abs 14657 df-struct 16558 df-ndx 16559 df-slot 16560 df-base 16562 df-sets 16563 df-ress 16564 df-plusg 16651 df-mulr 16652 df-starv 16653 df-sca 16654 df-vsca 16655 df-ip 16656 df-tset 16657 df-ple 16658 df-ds 16660 df-unif 16661 df-hom 16662 df-cco 16663 df-rest 16769 df-topn 16770 df-0g 16788 df-gsum 16789 df-topgen 16790 df-pt 16791 df-prds 16794 df-xrs 16848 df-qtop 16853 df-imas 16854 df-xps 16856 df-mre 16930 df-mrc 16931 df-acs 16933 df-mgm 17933 df-sgrp 17982 df-mnd 17993 df-submnd 18038 df-mulg 18307 df-cntz 18529 df-cmn 18990 df-psmet 20173 df-xmet 20174 df-met 20175 df-bl 20176 df-mopn 20177 df-fbas 20178 df-fg 20179 df-cnfld 20182 df-top 21609 df-topon 21626 df-topsp 21648 df-bases 21661 df-cld 21734 df-ntr 21735 df-cls 21736 df-nei 21813 df-lp 21851 df-perf 21852 df-cn 21942 df-cnp 21943 df-haus 22030 df-cmp 22102 df-tx 22277 df-hmeo 22470 df-fil 22561 df-fm 22653 df-flim 22654 df-flf 22655 df-xms 23037 df-ms 23038 df-tms 23039 df-cncf 23594 df-limc 24580 df-dv 24581

This theorem is referenced by: ftc2 24758 ftc2nc 35455

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