On exact constants in inequalities for norms of derivatives on a finite segment

We prove that, in an additive inequality for norms of intermediate derivatives of functions defined on a finite segment and equal to zero at a given system of points, the least possible value of a constant coefficient of the norm of a function coincides with the exact constant in the corresponding M...

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Date:1999
Main Authors: Babenko, V. F., Uedraogo, Zh. B., Бабенко, В. Ф., Удраого, Ж. Б.
Format: Article
Language:Russian
English
Published: Institute of Mathematics, NAS of Ukraine 1999
Online Access:https://umj.imath.kiev.ua/index.php/umj/article/view/4588
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Journal Title:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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author Babenko, V. F.
Uedraogo, Zh. B.
Бабенко, В. Ф.
Удраого, Ж. Б.
Бабенко, В. Ф.
Удраого, Ж. Б.
author_facet Babenko, V. F.
Uedraogo, Zh. B.
Бабенко, В. Ф.
Удраого, Ж. Б.
Бабенко, В. Ф.
Удраого, Ж. Б.
author_sort Babenko, V. F.
baseUrl_str https://umj.imath.kiev.ua/index.php/umj/oai
collection OJS
datestamp_date 2020-03-18T21:09:14Z
description We prove that, in an additive inequality for norms of intermediate derivatives of functions defined on a finite segment and equal to zero at a given system of points, the least possible value of a constant coefficient of the norm of a function coincides with the exact constant in the corresponding Markov-Nikol'skii inequality for algebraic polynomials that are also equal to zero at this system of points.
first_indexed 2026-03-24T03:01:43Z
format Article
fulltext K O P O T K I H O B I ~ [ O M J I E H H ~ I Y~,K 517. 5 B. | ]~ateHKO, ~ . ]~. Y~tpaoro (J3[HenponeTp. yH-T) O TOqHIdX KOHCTAHTAX B HEPABEHCTBAX ~!JIH HOPM IIPOH3BO~I-H~IX HA KOHEHHOM OTPE3KE We prove that, in the additive inequality for norms of intermediate derivatives of functions which are defined on a finite interval and are equal to zero in a given system of points, the least possible value of a constant with the norm of function coincides with an exact constant in the corresponding Markov- Nikol'skii inequality for algebraic polynomials which are also equal to zero in this system of points. ~oBeRetlo, IaO B a~ilTgBHitt HcpiBHOCTi /~JDI HOpM npobliXHHX IIoxi~HrlX d~yHKlljfl, ~lKi BH:lnaqeHi Ha CKiHqeHHOMy Bi/Ipi3Ky i/~opiBHIOIOTb Hy.qlO y 3a~aHi~ CllCTeMi TOqOK, HaflMellule bro~K./IHBe 3HaqeHH~i KOHCTaHTH npH HopMi qbyHKtli[ cniBna/~ar 3 TOqHOIO KOHCTatrroIo y alByloBi/lHig HepiBHOCTi THny Map- KOna--HiKo~n,CbK01"O/UIJ~ a.qFe6paiqHHX no~iHOMiB, gKi Te~K ~topiBlllOrOT~ Hy~no y Rill CllCTeMi TOq0K. riyc~ Lp=Lp[O, 1], 1 <_p <_o o, ii.llp= I1"11~. 06oaHa~IHM tlepe3 Lp, n ~ 1~1, MHO~KeCT~ ~a~anH~x Ha [0, 1 ] qbyHK~I~fl X, I~Memm~x a t c o m o T n o Herlpep~BHyrO rlpOH3BO/~HylO X (n- 1) (X(0) : =X) H TaKHX, qTO X (n) r L e. H3SeCTHO, wro g a a mot r~x p, q, r e [ 1, ** ] H /~ n e 7: +, 0 < k < n , c y m e c r ~ y - mT KOnCrarrna A H B TaKHe, ~rro n ~ a Kaz~ao~ qbym<mm x ~ IIx(~)llq _< A Ilxllp + Bllx~)ll. 0) Ecym RR c L~, TO nOS[O~KHM A ( ~ , k ; p , q ) : = i n f A , r~te i n f A 6epeTca rio BceM A raXaM, ~"ro c HeKoropo~t KOHCrarrro~t B Hepa~eHCr~O (1) rn~eeT Mec'ro Z~na :noto~a qbyHKtmn X e ~2. ~ICHo, q'ro r~e A(Ln, k ; p , q ) > M(~'n- l ,k;p;q) , M ( Q , k ; p , q ) : = sup p.-,, Q II Pn-I ~, (2) - - TOqHa.,q KOHCTaHTa S HepaBeHCTBe THna MapKoBa--HrlKO.rlbCKOFO/~.rlJ! a.nretpaH- qec~Hx nommoMon Pn- l, nprma~Jie~KamHx za,aaHHOSCy noz~rpoc'rparxcT~y Q rrpo- crpaHc 'ma ~'n-I BCOX IIOJIHHOMOB CTeHeHH He BHmr n - 1. B. I4.BypenKor~ [ l ] ~ o K a z a ~ , ' r r o r r p H Bcex p , q , r r [1 ,**] H k = n - 1 A( n , ~.. (3) B. O. ]3ateHKO, B .A . KoqbaHos H C. A . l ' IHqyros [2] ycraHosHJm paBeHCTBO (3) rlpH Bcex n, k e ~-+, O<k <n. I'IycTb 3a~aHt~ MHoa<ec~a T-- {tl . . . . . t t}c[0, 1], O<tl<t2<...<tt_l<tt<l, �9 B. q>. BABEHKO. ~K. B. Y3JJ.PAOFO, 1999 ISSN 0041-6053. Ygp. ~lam. ,ucyp~, 1999, m. Jl , N e I 117 I18 B. ~. BABEHKO, ~. B. Y"b/2PAOFO H m = {mi . . . . . mr] C N TaXOe, tiT0 Iml := El f lmi ~ n-1. O603HaqHbl qepea (7", m) ~ o ~ z e e m o ~ y a z ~ x e L7 Tar, Hx, ~ 0 (J) x ( t i ) = 0 , i = 1 , 2 . . . . . /, j = 0 , 1 , 2 . . . . . m i - 1 . (4) l'IycTl, ralOKe fin-I (T,m)--MHOaCeCTBOnOJnmOtnOS Pn-l e f in- l , y~osJ1eTBO- pmottmx ycJmeaJ~t (4). ~ICHO, wro npH ecex n, k, p, q, r A( I~ (T ,m) , k ;p ,q ) > M(f in_ l (T ,m) ,k ;p ,q) . (5) A. H. 3nsrHnttee [3] aoKaza.n, aTO npH k = n - 1, H T c { 0, 1 } e (5) maeeT rnecTo paBeHcrao. TeopeMa. }/n~ atO6btX T, m, n, k, p, q, r A (1~( T,m),k;p, q)= M ( f i n - I ( T, m),k;p, q). (6) ,~or 3aqbrmcrrpyeM npoaaBOJll, h ' I~ Ha6op qHCell m'={m[...., In[ } TaxoIt, wro ] m' ] = n H m~ > m i ]~Jm i = 1, 2 . . . . . I. Kax HSBeffI'HO (CM., Hanpar.tep, [4, c. 25-27, 113-1171/ , / I J~ Jno6o~ qbym<tmrl x e L n cymecTsyeT e/mHCTBerm~l~ nozmHoM Pn- I (x; t) e fin-1 (mrrcpnoJtm~ox~mafl noJmnoM ~pmrra ) razoR, wro P(nJ~(x;,ti) = x(J)(ti), i =1,2 ..... I, j =0, I ..... m~-l. Yqrrr~sa~, wro Jno6ylo qbyHzmno x e L n MO~Z_HO npe~cTaBa'r~ e Brtae 1 1 n-I ~Ct) = en-l (t)+ i,,_1)J~Ct-u)+ ~c"~(u)au, r~c Pn-! ~ nO.nHHOM Te/4.rtopa dpyHKt~H X, pazHOCTb x(t)-Pn_l(X; t) npeI~cTaB- ./L~M B BI4~e x(t)_Pn_l (x;t) = 1 [lG(t,u)x(n)(u)du" (7) ( n - l ) ! J 0 r~e G(t,u) = (t-u)~. - l - Pn_l(('-u)+-l,t). ]~a.nee mdee~ �9 n-~ (nil)iJoff-t ~G(t'u)x(n~(u)du" (8) Ha (7) H (8) J~erxo cJ~eRye'r, wro GylI~e, CTBylOT KoHCTaHTM C H C k Tazrle, wro I I x - P . - l ( ~ , .)11~ <- r (9) tI llxCt) p.ck). - .-i tx; .)llq < Ckllx(n)ll,. (10) O'rMe ' r~ ' ra r , x e , wro,a.aa x e [~(T,m) 6y~eT P,,_l(x;, . ) ~ f i , - I (T, m) . ./]ettcTnya no npea,.~oxetmott B. $ . Ba6enxo, B.A. Koc~aaoeb~'~ H C. A, I 'h,~yro- ISSN O041-605& Yr, p. ~m. ~ytm.,1999 , m. $1. N ~ I O TOClHHX KOHCTAHTAX B HEPABEHCTBAX ~Ml$l HOPM FIPOH3BO~-IHX... 119 SS~ CXCMe [2], ~J~q J~m6Og cl)yHZm~H X r ~(T, m ) m~ces~ (~s~ coKpameHHS aam~- cel~rmace M = M (ff'n=l ( T , m ) , k ; p , q ) ) llx(k)llq < II "n-ll)(k)(X, ")llq + llx ct)- Pn<t~- (x, ")llq < <- e l l en - t (x , ' ) l l p + IlxC~)-P(,~_~(x,')ll~ < -< M(ll,~llp + II~- ~_~(x,-)llp) + II ' : t ) - "n-~)'(~) ( x, ")llq = = g II ~llp + g IIx-e#-~ (x,.)ll~ + II~ <t)-,#_~,'ck) (x, ")ll~ OTc~ona, y , - ia 'n~a.a (9) H (10), no.)D,'-IaeM llx<k)llq < g II x II~+( CM+ C~ )II x(#)llr. TeopcMa ~oKaaaHa. Ilyc'~ Tenepb ~:~ Jno6oro I = I, 2 ..... 1 3a~aHo npoH3eOSmHoe nO~MHO)KecrsO l i C { O, 1 . . . . . m i - 1 }. tIepea Er ~ (7", l ) O603tla~lHM MHO~ZeCTBO (]3yI-IKUHI~ X ~ L n TaKHX, tITO x(J)(ti) = 0, i = 1,2 ..... I, jel i. (11) H3 npHBC]ZeHHoro ]~oKa3aTcJibcrsa c~e~yev, ~rro ZoHcrarrra A(L~ (T, 1), k ; p, q) coBna~aeT ( npH Bcex n, k, p, q, r) c TOqHO~ zoacvarrroa ~ Hcpase~c'rse T~na Map- KOBa -- H~KOJ~czoro nJ~a noJ~m~o~oB Pn-I e ~rn..l, y]~O~eT~Ops~or~HX yCJ~OSH- m~ (11). 1. Eypen•o6 B. H. 0 TOqtlHX nOCTO~lmt~x B ItcpaBeHCTBaX ~1~1 HOpM npoMexyTOqtlt~X npoH3BO~- ntax aa KOVeqHOM mrrepna~e//Tp. MHAH CCCP. - 1980. - 156. - C. 22-29. 2. Ea6eH~o B. a)., KoqbaHo~ B. A., llu~yzo6 C. A. 0 nepascttcTtmx Tana KostMoroposa ~:t#t dpyHK- tm~ 3a~mHm~x im zoxeqnost OTpC3Ke//Yzp. ~taT. )zyptl. --1995. --47, I~ I. -C. I05-I07. 3. 3oaeuntieo A. M. HepaBeHCTna C TOqilblMH [IO~FO2tiHbiMH .ffJl~l HopM HpOMe2KyTOMHblX IlpOH3BO~= max//Mew,,~yHap. KOa~. ,r npoc'rpaHc'r~ TeopHa npa6~Mw, eHuR, tle.JltlHe~HHa aHaJltl3", noceau~emtaa 90-.~e~m a~a~. C. M. Huxo~bcKoro: Tea. ~OK.~. (MocKBa, 27 anpe- ~a - 3 ~ 1995 r. ). - M . , 1995.- C. 131-132. 4. Typeulcu~ A.X. Teopus mrrepnoampoBamaa e 3a~aqax. -M~HcK: Bumettm. tuK., 1997. - T. 2. - C. 25-27; 113-117. Ho.qy~lCHO 21.08.96 ISSN 0041-6053. YKp. ~wan. ~.'~pn., 1999, m. 51,1~ 1
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spelling umjimathkievua-article-45882020-03-18T21:09:14Z On exact constants in inequalities for norms of derivatives on a finite segment О точных константах в неравенствах для норм производных на конечном отрезке Babenko, V. F. Uedraogo, Zh. B. Бабенко, В. Ф. Удраого, Ж. Б. Бабенко, В. Ф. Удраого, Ж. Б. We prove that, in an additive inequality for norms of intermediate derivatives of functions defined on a finite segment and equal to zero at a given system of points, the least possible value of a constant coefficient of the norm of a function coincides with the exact constant in the corresponding Markov-Nikol&#039;skii inequality for algebraic polynomials that are also equal to zero at this system of points. Доведено, що в адитивній нерівності для норм проміжних похідних функцій, які визначені на скінченному відрізку і дорівнюють нулю у заданій системі точок, найменше можливе значення константи при нормі функції співпадає з точною константою у відповідній нерівності типу Маркова - Нікольського для алгебраїчних поліномів, які теж дорівнюють нулю у цій системі точок. Institute of Mathematics, NAS of Ukraine 1999-01-25 Article Article application/pdf https://umj.imath.kiev.ua/index.php/umj/article/view/4588 Ukrains’kyi Matematychnyi Zhurnal; Vol. 51 No. 1 (1999); 117–119 Український математичний журнал; Том 51 № 1 (1999); 117–119 1027-3190 rus en https://umj.imath.kiev.ua/index.php/umj/article/view/4588/5880 https://umj.imath.kiev.ua/index.php/umj/article/view/4588/5881 Copyright (c) 1999 Babenko V. F.; Uedraogo Zh. B.
spellingShingle Babenko, V. F.
Uedraogo, Zh. B.
Бабенко, В. Ф.
Удраого, Ж. Б.
Бабенко, В. Ф.
Удраого, Ж. Б.
On exact constants in inequalities for norms of derivatives on a finite segment
title On exact constants in inequalities for norms of derivatives on a finite segment
title_alt О точных константах в неравенствах для норм производных на конечном отрезке
title_full On exact constants in inequalities for norms of derivatives on a finite segment
title_fullStr On exact constants in inequalities for norms of derivatives on a finite segment
title_full_unstemmed On exact constants in inequalities for norms of derivatives on a finite segment
title_short On exact constants in inequalities for norms of derivatives on a finite segment
title_sort on exact constants in inequalities for norms of derivatives on a finite segment
url https://umj.imath.kiev.ua/index.php/umj/article/view/4588
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