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Mirrors > Home > MPE Home > Th. List > nmrtri | Structured version Visualization version GIF version |
Description: Reverse triangle inequality for the norm of a subtraction. Problem 3 of [Kreyszig] p. 64. (Contributed by NM, 4-Dec-2006.) (Revised by Mario Carneiro, 4-Oct-2015.) |
Ref | Expression |
---|---|
nmf.x | ⊢ 𝑋 = (Base‘𝐺) |
nmf.n | ⊢ 𝑁 = (norm‘𝐺) |
nmmtri.m | ⊢ − = (-g‘𝐺) |
Ref | Expression |
---|---|
nmrtri | ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (abs‘((𝑁‘𝐴) − (𝑁‘𝐵))) ≤ (𝑁‘(𝐴 − 𝐵))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ngpms 23209 | . . . 4 ⊢ (𝐺 ∈ NrmGrp → 𝐺 ∈ MetSp) | |
2 | 1 | 3ad2ant1 1129 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → 𝐺 ∈ MetSp) |
3 | simp2 1133 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → 𝐴 ∈ 𝑋) | |
4 | simp3 1134 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → 𝐵 ∈ 𝑋) | |
5 | ngpgrp 23208 | . . . . 5 ⊢ (𝐺 ∈ NrmGrp → 𝐺 ∈ Grp) | |
6 | 5 | 3ad2ant1 1129 | . . . 4 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → 𝐺 ∈ Grp) |
7 | nmf.x | . . . . 5 ⊢ 𝑋 = (Base‘𝐺) | |
8 | eqid 2821 | . . . . 5 ⊢ (0g‘𝐺) = (0g‘𝐺) | |
9 | 7, 8 | grpidcl 18131 | . . . 4 ⊢ (𝐺 ∈ Grp → (0g‘𝐺) ∈ 𝑋) |
10 | 6, 9 | syl 17 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (0g‘𝐺) ∈ 𝑋) |
11 | eqid 2821 | . . . 4 ⊢ (dist‘𝐺) = (dist‘𝐺) | |
12 | 7, 11 | msrtri 23082 | . . 3 ⊢ ((𝐺 ∈ MetSp ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋 ∧ (0g‘𝐺) ∈ 𝑋)) → (abs‘((𝐴(dist‘𝐺)(0g‘𝐺)) − (𝐵(dist‘𝐺)(0g‘𝐺)))) ≤ (𝐴(dist‘𝐺)𝐵)) |
13 | 2, 3, 4, 10, 12 | syl13anc 1368 | . 2 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (abs‘((𝐴(dist‘𝐺)(0g‘𝐺)) − (𝐵(dist‘𝐺)(0g‘𝐺)))) ≤ (𝐴(dist‘𝐺)𝐵)) |
14 | nmf.n | . . . . . 6 ⊢ 𝑁 = (norm‘𝐺) | |
15 | 14, 7, 8, 11 | nmval 23199 | . . . . 5 ⊢ (𝐴 ∈ 𝑋 → (𝑁‘𝐴) = (𝐴(dist‘𝐺)(0g‘𝐺))) |
16 | 15 | 3ad2ant2 1130 | . . . 4 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝑁‘𝐴) = (𝐴(dist‘𝐺)(0g‘𝐺))) |
17 | 14, 7, 8, 11 | nmval 23199 | . . . . 5 ⊢ (𝐵 ∈ 𝑋 → (𝑁‘𝐵) = (𝐵(dist‘𝐺)(0g‘𝐺))) |
18 | 17 | 3ad2ant3 1131 | . . . 4 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝑁‘𝐵) = (𝐵(dist‘𝐺)(0g‘𝐺))) |
19 | 16, 18 | oveq12d 7174 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → ((𝑁‘𝐴) − (𝑁‘𝐵)) = ((𝐴(dist‘𝐺)(0g‘𝐺)) − (𝐵(dist‘𝐺)(0g‘𝐺)))) |
20 | 19 | fveq2d 6674 | . 2 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (abs‘((𝑁‘𝐴) − (𝑁‘𝐵))) = (abs‘((𝐴(dist‘𝐺)(0g‘𝐺)) − (𝐵(dist‘𝐺)(0g‘𝐺))))) |
21 | nmmtri.m | . . . 4 ⊢ − = (-g‘𝐺) | |
22 | 14, 7, 21, 11 | ngpds 23213 | . . 3 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝐴(dist‘𝐺)𝐵) = (𝑁‘(𝐴 − 𝐵))) |
23 | 22 | eqcomd 2827 | . 2 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (𝑁‘(𝐴 − 𝐵)) = (𝐴(dist‘𝐺)𝐵)) |
24 | 13, 20, 23 | 3brtr4d 5098 | 1 ⊢ ((𝐺 ∈ NrmGrp ∧ 𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋) → (abs‘((𝑁‘𝐴) − (𝑁‘𝐵))) ≤ (𝑁‘(𝐴 − 𝐵))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ w3a 1083 = wceq 1537 ∈ wcel 2114 class class class wbr 5066 ‘cfv 6355 (class class class)co 7156 ≤ cle 10676 − cmin 10870 abscabs 14593 Basecbs 16483 distcds 16574 0gc0g 16713 Grpcgrp 18103 -gcsg 18105 MetSpcms 22928 normcnm 23186 NrmGrpcngp 23187 |
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 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-sep 5203 ax-nul 5210 ax-pow 5266 ax-pr 5330 ax-un 7461 ax-cnex 10593 ax-resscn 10594 ax-1cn 10595 ax-icn 10596 ax-addcl 10597 ax-addrcl 10598 ax-mulcl 10599 ax-mulrcl 10600 ax-mulcom 10601 ax-addass 10602 ax-mulass 10603 ax-distr 10604 ax-i2m1 10605 ax-1ne0 10606 ax-1rid 10607 ax-rnegex 10608 ax-rrecex 10609 ax-cnre 10610 ax-pre-lttri 10611 ax-pre-lttrn 10612 ax-pre-ltadd 10613 ax-pre-mulgt0 10614 ax-pre-sup 10615 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3496 df-sbc 3773 df-csb 3884 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-pss 3954 df-nul 4292 df-if 4468 df-pw 4541 df-sn 4568 df-pr 4570 df-tp 4572 df-op 4574 df-uni 4839 df-int 4877 df-iun 4921 df-br 5067 df-opab 5129 df-mpt 5147 df-tr 5173 df-id 5460 df-eprel 5465 df-po 5474 df-so 5475 df-fr 5514 df-we 5516 df-xp 5561 df-rel 5562 df-cnv 5563 df-co 5564 df-dm 5565 df-rn 5566 df-res 5567 df-ima 5568 df-pred 6148 df-ord 6194 df-on 6195 df-lim 6196 df-suc 6197 df-iota 6314 df-fun 6357 df-fn 6358 df-f 6359 df-f1 6360 df-fo 6361 df-f1o 6362 df-fv 6363 df-riota 7114 df-ov 7159 df-oprab 7160 df-mpo 7161 df-om 7581 df-1st 7689 df-2nd 7690 df-wrecs 7947 df-recs 8008 df-rdg 8046 df-1o 8102 df-oadd 8106 df-er 8289 df-map 8408 df-en 8510 df-dom 8511 df-sdom 8512 df-fin 8513 df-sup 8906 df-inf 8907 df-pnf 10677 df-mnf 10678 df-xr 10679 df-ltxr 10680 df-le 10681 df-sub 10872 df-neg 10873 df-div 11298 df-nn 11639 df-2 11701 df-3 11702 df-4 11703 df-5 11704 df-6 11705 df-7 11706 df-8 11707 df-9 11708 df-n0 11899 df-z 11983 df-dec 12100 df-uz 12245 df-q 12350 df-rp 12391 df-xneg 12508 df-xadd 12509 df-xmul 12510 df-fz 12894 df-seq 13371 df-exp 13431 df-cj 14458 df-re 14459 df-im 14460 df-sqrt 14594 df-abs 14595 df-struct 16485 df-ndx 16486 df-slot 16487 df-base 16489 df-plusg 16578 df-mulr 16579 df-tset 16584 df-ple 16585 df-ds 16587 df-0g 16715 df-topgen 16717 df-xrs 16775 df-mgm 17852 df-sgrp 17901 df-mnd 17912 df-grp 18106 df-minusg 18107 df-sbg 18108 df-psmet 20537 df-xmet 20538 df-met 20539 df-bl 20540 df-mopn 20541 df-top 21502 df-topon 21519 df-topsp 21541 df-bases 21554 df-xms 22930 df-ms 22931 df-nm 23192 df-ngp 23193 |
This theorem is referenced by: nm2dif 23234 |
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