SUT Joumal of Mathematic§....
(F()rmerly TRU Mathematics). Volume 27, Number 2(1991),151−167SOME APPLICATIONS OF THE MEAN VALUE T正IEOREM
IN DIFFERENTIAL CALCULUS BY
THE METHOD OF.RANKED SPACES
MASATO HIKIDA
(Received September 25,1991) Abstract. In differe皿ti…il calculus in lmear ra皿ked『 唐垂≠モ?刀@with亘o皿一sym皿etIlc P,e。。ighb・・h・・d・,・PPIyi・g・th・・m誕・al・・th…em・f N・g・k…[3】・w・gi・・ theorems o皿differe皿tiabdity of a limit map孤d o皿.paltial dexivatives・ 1991ルf¢t九ematics 5鯵D∫εcオClassification.46A99,58C20. κ・yw・rd・. Rank・d・p㏄・, N・n−・ymm・t・i・p・e・・ighb・止・・d・M・・n v寧・th・・一 工em, Stolz,S angular domain・ ’ Th, p岬・・e・f縮p・p・・i・t・9i・…m・apPli・ati…㎡th・m・an・al・・th…em 。f・Na9。[k…固i・・diffe・e嚇・al・Ul・・血五・・a・・ank・d・paces・i…,th・・e t・品・一 ,nti。bthty㎡・limit・m・麺d t・p・姻d・・ivati・…O・・st・ndp・i・t・f d・v・1・pi・g・ th。。,y i、 t・w・・k・・nstru・ti・・ly i・・i岨…㎡9・n・・ality,・・w・唖t・k・rP be− i。g i・th・・cat・g・・y㎡9ive・・p≡孤d t・ay・id・・mpli・ati…品m・・h・・p・・sibl・・ Th。 inv。・tig・ti・n md・i・[3]・・it・th・・tandpd・t・Th・・th・m・th・d tak・n i・thi・ P・Pe・i・diffe・ent丘・m th・・e㎡・th・・th・・亘es・f価・ential・al・ulus i・h・・a・spaces: Ap,en・ighb・・h・・d・・f・th・・亘gi・㎡・li…r・a・k・d・p㏄・iS・i・g・n…}P・ith…p・・ (i。th・t。P・1・gi・al・e眠)…sy㎜・t・i・,・・d heed・・t訪…回l pd・tr gf th・ ,p。,e坤e c・n…g・nce i・ah…r・ranked・p㏄・i・d・丘・・d by m・an・・f・血・d・m・pt.al ,eq。,nce・f p・en・ighb・・h・・d・, pl細y・p・aki・g,・・equ・nce・f p・i・t・i・・⑭・ed t・ 。。n…g・t・apd・t・al・・g・gi・・n・P・th;㎝d・・th・d・・ivati…f・m・p・t・p・i・t is n°t reqUi,ed,・t・hav・th・wh・le sp㏄・・s it・d・頑・・f d・丘niti・n・O咀e・顕whi・h yi・ld some known theorems whe/n the spaces.a正e nolmed, are apPlicable to nonrtopological sp㏄es・ . ‘ .Th,。ugh・ut・thi・p・Pe・,・‘fli・・a…ank・d・pac・”m・an・a・lin・aロ・n㎞d sぽ・f [3],and・・w・ c・nform…se1…t・th・. t・rmi・・1.99y・and・,・th・.・・t・ti・n・・f【2]a・d【3]・ Several of those are given in ApPendix・ 、 tt、一.... ..・・ .、151
152
AP肌ICATIONS OF MEAN V肌UE TH亘O臨M’く.
≡悩cii壷⊇㌫縞ξ扁。‘砺但斑譲逼誌亘16麺・益亘壷。蔽ニイ
qu・nce・in・Un・碇・江n滅Sp漣E・・㎡鋤e・S恨苫留‘}ぷ1;6f>汽(E)・・e丘・qu・ntly W士itt・n酬,…⑭r辱卵1≡輌.gn㌧.…,....・、:∵』.1二・..〇三 E・・(E)={v∈T・(E)・th・”.・填輌OiS.琴.』int・・i・r P・i・t・f Ek(v)}, A = {{λ」}: λ」>Oandλ」→0}; and when v∈万(E), we put 9(∋={{hi}・{hj}i・㎝れ一quasi b・und・d seque血ce・in・E}. 「‘ .・・ ’. ’ミこ..’ r:.’ぺ .ttt「.・:… ’・ ∫:二・‘::..,}.:.1. 1・二『 .『・「ヨ;: 1:..:....〈.一.:三ご:=M°「e°ve「,1’f°「.託隅興ρ・{4・}〔d国:9f§蹴・1・f・西1』鋼・遮』㎝・ly
d・n・t・th・・eq・・nce・・{λ進8た}bY二伍}士.{カk}t『・e命ectiV・ly;一・a・d;lthさh緬・・ {Ak}〈{Bk}means that f()r any k there is k’such that Ak’⊂B夫. Let us recall some fundamen城notio耶(9£121,、.[3])・・.L.et. ,E pnd.∬be耳皿e聖;anked spaces and assume that F is(π一T1)and satis五es the colldition(A.4)of[3]:(A.・ド1.i}微}〉ξ』筋and:i頑6・磁誠}(砺∈藤晦』y
intersection, then there is{k(i)}(ゐ(り↑oo)such that{エ友(輌)十W『κ‘)}is a fundament瓠 sequence and thatエ」十Wj・⊂霊夫(t)十Wk(‘)whenever j≧k(i十1).ご認£竃に慧蕊霊㌫蕊蕊1筆、1∫霊蕊?隠蒜:,.
the’・’e:iき:「U『層∈島‘の’・S’i ’/6h…t五・t..{ヂ(b、〈孤(、))hD)・一∫(・)}く・一・Of.・A9曲6 tha v∈.塩⑮枷dLぶ漁・ihtε・i・・p・i・t・fD・・Th・h∫.iぎ・did・t6・be R一か晒ε硫b’,・・喚…;.e垣r竺・…i輌1・面m・.酬・)’4・’F・li・・h蹴h・鋼・・.
与6rd si・.’thごオε「i・ω.栖(LFT)・u・h t嵐号’1ア(λSh)一)』→−0(P二ψ)島・・e・e’・y:{㌧}.∈..2(の and「?磨E・y{λ」}d;紬・fe…・(九)=∫(・+九)L∫ω弓(ん)伍・(D−・・)酬り)・and・ 滅th6麺2泌Ch irniiiq・・ly dをゆ・・d:in世(・),’i・・allttd・the ’R−v−d・)ivatibe’ Df」 f”d・t’.白ahd’i§.den6ted’byア(d;’v)ot’ btiefly. by∫’てδ)∵And∫is、顧d.tO.be v・ eO’ ntinuou/5 ( J , tlr6sD:二.R・必渉r撚05£ε)・亮5⊂D・fi蹴6。㎡・i…唾・P..Mi娩…叔・)at e硬士プp這htめfS∵More(壷er,:∫is’Said t6 bC coηオ栖冠砿31(resP∴R三宙膨柁施:舌返6オε).『at!αi毛ビ籔鶉蕊鷲耀禮1二認;慧慧こ1:蒜㍑㌶三㌶蕊
’ , E , ’ (t6sl ! ・i ’ ’ R: diff辿iel㎡tia泣e) oni』S二(:’1),,泣6]丘sbd’si㎡1arly’tO}the・一’Sb()Ve. /.tご∴.・∴.㌻㌧∵・,1’・’ In a hnear ranked space, a O−fundamental sequence{Wk}is said to be c∂n’v・ex’(興:.⑳品溺e読繊一is‘と・碩剛魎緬耽tfi・);血d,翻hear・血k6d否pk・
i・謝:tも』・泌侮P:し㊨翻司’if:the㌔α血nd・血e’・tal・ Si・q・・n・e・i・the蹴e・ are・c・nvex(resp. symmetric)書 ..・1二^∵∫.・1;・1・.・...∵・.∵1・・…i・・.…’t 、「・
lごHIKIDA
^t153
・Nagakura[3】pτoved:the伺1〈)wing:. .『冠,. ’. . .・. , MEAN VA七uE THEoREM([3, Theorem 3』). LeεFbe a.(π:Ti)’linear ” ranked 鋼・…輌9(A・麺4(A’・2°)・;W:[・,用.(⊂盆・)=・ F・a・d・di・[・,用てぽ)→ R・・.』ψ<β・.S卿・・9,’ tb4t’ b ・hd蜘・’…‘」一・.・・[・・用鋼藺e R一 繊・㎝‘f・ロ・b・[α,β)\J,iVh・たJ・ぬt m・6‡伽・t・bl・;頷d・・PP・・e・th・‘φ」・ m、,h。‘。。。。。h二dee−ing..F・・th・㎞・鵬・・PP・面h・t,’f・i…me c㎝陀W∈’T6(∬), 9([α,β])⊂登(th)and.9’([α;β)\」)⊂E.(w)11fθjs a cOnvex言ubseガof F Su(血that B∩E’(ω)≠O・and.」fg’(Z)∈φ゜θ8血距∈[α,β)\J, th… 9(β)−9(α)∈(φ(β)一φ(α))孕(P一ω)・ Itt the abo寸e,. Ri.denotes the li皿ear ’ranked’ space(R,{Vn}), whele R is the rea1 丘・ld;・Vo三{[0,・)・ε>1}U{丑}.and W・=「{[0,・)三(n’+1)三1ぐξ≦n−1}fo・・n≧1; g:θ=0’(‡)(1)and.φ(t)=φ’(オ)(1)∫and(A.2°)is the folleWing’ton’dit輌6n which is a modificationドof(A.2’).of[3]:’』.’ t..∫ 一’ (A:2・)』「il xt/’4ti(P)in F血d if;劔.品垣eUr’漏倒,♂ξ醐拠dち・B(it) ’飴固1『th・’・uM・i・面y l飢9・」’・1麺・」・→・ll(P−・)・.. 一 ゼ ‘.. l i . − Th・C・n・・Xity− gf、ω…d・t・kin9,th・P一ひ・1・・U・・ρロ・・e e領・嚇.垣th≡an vぬ・ ・hg・・e皿(9f, .[5.,(1.32)〕坤・・p灸・e・ 9iy・n i・・h?P・。・f.㎡[与,(1,3・?)/・・e・eg・・d・d… li……k・d・p㏄・・,・・d th・・th・p・・㎡hdd・t・u・f・・th・・e hn9飢工・蝸興・・), 1・Limitr.・f.diffg・e輌b10 m鋼Th・Cμgh・・t.t恥secti・n,.1・t E and F b・ lineaロa皿ked spa£es and assume that F is(π一T1)and satis丘es(A.4). Asequence{九}of maps,九:D(⊂E)→F(η=1,2,_),is said to be unifdrmly・・励・rg・ぬ・α卿∫・D→F・n S.⊂D3・if th・r…Xi・t・・={Uk}∈冗(F)…h
that∼fbr any le,. there isη為、such thatη≧n斥,i耳1plies fn(x).7∫(x)∈阪一Uk fQr姐 ¢∈S. :.. ,.t、・・...:・..、 ・.、、. 三・:,,in. the皿owing Theolemsユー3,−let」),1)e.ian’Rrv−gpen s耳bset of.、臥{br some v∈ 尤。。(E)arld.t、aP・um・.th・t.F.i・・c・皿ve・’..and・atiS丘・s.th・1・・嘩qn・(A・2r)孤d・th・ 飼lowing(Aユ9): 、...’i:・・、.・ }..、: .・.二・t./. ・: ・.・・ ∵(A.1・)・F・t 5・y・ tii』e S。(F)th・・e.i;.・21∈X・・(F)ざ・・h th・t’Oli『k碗・THEoREM 1. Let F be cαnp輪L・t fn・1)→F(n=1,2,…)be』−
diffe,enti。bl・・n D,吐・肥v={Vk}. L・け・D→F・ana・・.⇔・S・PP・・e t五・t th・f・ll・唖g(・)一(・)h・)ld.:. //…・・:’、∵.・・.」‘.二.’x.s (・){fn}is・・vnifo・跡c・・velgent・t・・f:・n.・・meα+Vi⊂. Q.n(蜘)+・)・154
APPLICATIONS OF MEAN VALUE THEOREM
(b)Th・・e e廊㌦∈T・(F)・・ch‘h・t, f・・each・n, th・τei5々・ch肪・は((・+ Vkn)∩D)⊂y(u、).・ (・)・皿・・e」・・’…血‘h・‘巧⊂(D一の∩ESr(∋and‘h・ちf・・㎝y 6X・rdん∈Vl, t力・ m・p(R・⊃)[0,1] DθH f.(・+θ九)∈∬」・c・皿‘輌n・…㎝[0,1]f・・ea・h・n. (d) There丞u2∈チb(F)such tha‘{プ蓋(α)(Vk∩E★(V))}先くq2 r u21br eachη. (・)Th・・e加・={σ・,・}.∈漏ぴ)…h鋤ち伊’v・n{ゐゴ}頑hん」→0(R,V), {yi}∈Q(のa・d.先, S・me・n。紐d j。 can・be・f・und・in…力a way that fA(・+んゴ)(y」) 一 fa(・+九」)(め)∈σ、,、」u3,、 whenever・m≧n≧n。 and j≧jo.・ Then f is R−v−d朋bren‘∫ab∫e a‘αand∫’(α)ω=P−u3−1imプニ(α)ω(y∈E★(v)). PRooF・If z.∈E(v), then{z}∈2(v);a皿d so, by(e), the sequence{fS(α)(z)}is P− Oauc克y by u3([4, Definition 3]). As∬is complete,{f(α)(z)}is para弔3・・co皿vergent to a point of F by[4, Propositio皿5]. A point y∈・E★(のcan be written as ・y=Σ多=1 z1ゴー Σ1=1z2,k, where zl,」,22,k∈Eω・Since f(α)ω=Σ」∫f(α)(z1」一Σk fl(α)(z2,k), u3十u3〈u3 and F is(π一Tl), the sequence{f(α)ω}has a unique P−u3−limit:We put gω=P−u3−lim fA(α)ω. The linearity of g:Et(v)→」『is obvious. We shall prove the v−continuity of g. Let{防}∈9(切. Given k, clloose mo>ksuch that 2U3,m・⊂U3,k・.Th・n, by(・)th・re・a・e・N・nd」・u・h th・‘f;(・)(yi)一一 fA.(・)(yi)∈ U3,mo一こT3,m。 wheneverρ≧n≧」V and j≧」. F口dng n andゴand letting.ρ→∞inthe prece(ling, we have ”’
9(yi.j−fA(・)(yj)∈U3,m。−U3,冊。(P−u、)⊂2(σ、sm。−U、,m。).Thus
fA(α)ω一9(yj・)∈u3,k−u3,k provided n≧.Nand j≧」. From this and』id)it follows that g is v−continuous at the origin, a皿d so it is v−continuous on Eピ(v). By(・), th・・e・eXi・ts・、={〃1,、}∈島(F)・u・h th・t, f・・’・ny k, th・・e i・n、.su・h th・t n≧nk irriplies f・(¢)一∫(司∈σ4,為一U4,A伽誠1¢∈α十V,. Chooseω={Wk}∈痴(F) such that u1十錫2十u3十u4司くw. Let{九」}∈0(∋and{λ」}∈A. Given k, choose m so 1arge that 7n>max{k, i,1},4Wm⊂Wk and Wm⊂・ESr(ω). Then there are Nl and Jl such that λ」九ゴ∈Vin, 」㌦(x)一∫(¢)∈Wm−Wm (苫∈α十Vm), f;(・+θλ」んゴ)㈲一・ fA(・+θλ」んゴ)(九豆)∈Wm−Win,,M.HIKIDA・” whe皿evelρ≧n≧、N1,」≧」1 a皿dθ∈p,1】. Fix n≧1VI a血d 5≧Jl fbr a、 wkile. For eachρ.≧・η, the Inap ・ , 9,・(R、⊃)[0,1⇔θ・→痴(・+θλ」九」)一み(・+θλ」九ゴ)∈F i・c・ntinu・…n[P,・],・・d i・R−diffb・enti・bl・・n[・,1)紐d 頭θ)=f;(・+θλ」九元Hλ」九ゴ)−fA(・+θλ」んゴ)(λ1九ゴ) ∈λ」(wバ陶(⊂E★(ω))・ Since gp([0,1])⊂2(Wm−Vγm)⊂仔(ω), the mean value theorem can be appHed and we have−』
@ .
9『ρ(1)−9P(0)=」ら(α十λ」んゴ)−fn(α十λ」㌧)一(ん(α)一九(α))∈λ」 Wm−Wm(P一ω) whenever p≧n。 L6ttingρ→oo in tke abov6, we obtain ∫(α十λ」ゐゴ)一九(α十λ」九」)一(∫(α)一九(α))∈λ」 W,n一照亘(P一ω),・ . ・inceλ」W冊.一照P一ω)1・P一ω一Fl・・ed・Th…f・r n≧N・㎝d j≧」・, λ71[∫(α十λゴ九」)−fn(α十λ」九」)一(∫(α)−」㌦(α))1 ∈ Wm−Wth(P一ω) .こ . ” (: 2(Wnt−Wm). For each n=1,2,..., put㌦(h)=プ』(α十九)一九(α)−fA(α)(ん)(九∈(D一α)∩E★(の)・ Thenλ;1rn(λ」九」)→0(P)asゴー→oo;and, ifゴis large, we have rn(λ」ん」)∈E★(ω)by (b)a皿d(d).Henceλ;1rπ(λ」ん」)→0(P一ω)as j→∞, by(A.2°);so there is jπsuch thatゴ≧」πimplies λ717rπ(λ」九」)∈VVm−Wm・ On the other hand, there areハr2 and J2 such that, for・n≧1V2 and j≧ゐ, f(α)(九」)−9(九ゴ)∈Wm−Wm. Now, putア(h)=・∫(α十ん)一∫(α)−g(九)(ん∈(D一α)∩E★(∋)and choo6e n≧ max{Nl,N2}・Then, if j≧max{」1,ゐ,」九}, λ71r(λ」九ゴ) = λ;1[∫(α十λ」んゴ)−fn(α十λ」んゴ)一(∫(α)−fn(α))】 +λ;1・・(λ」九ゴ)十f(α)(九ゴ)−9㈲、∈“バ閣⊂晦7晩,
whi・h・h・w・λ;1ヂ(λ・h3−)→・(P一ω)・Thti・th・pi…fiS・。mp嵐 tt E『155
・156
APP口CATIONS OF MEAN、V肌U.E THEOREM
T臨oREM’・2. Let’.F. be cgmpk‘α∴・Le‘fnゴD→F・(n』=1,2,.∴.)be R・砂一 直醗τ㎝¢∫able㎝1), where・v=伍}. SUPP・⑤e伽ち劔s㎝e 6.・∈Dl¢力e・sequence 仏(b)}has・c p一五頑a頑孕at tht.rr i・、輌φ‘ha‘ロ.(ρ二;)∩P’(”) and th・ follow劫t9(f)一(h)hOla: ”h (f)Ther・」…∈乃(F)S・・th・・伽‘.み.(b+均⊂ぽω、fo・ρ紺yη・..・・:t.t−、㌶、芸牢;‘+V”(;二(d)・ p伽eO興(’〔n(c)一(d)卿
(h)TheT・」・u={Uk}∈,1 To(F)S・c励aち.9i.fen.{yi}.∈9(v)ahd k, S㎝・.鞠≡dljl c竺be:φu亘輌su(th.a1陥y廻..、.、.、....、・.、.tt , ,
fA(x)(防)−f(司(防)∈Uk−Uk .《・』 whtinevef m≧.ゐ≧nO,ナ≧jo a亘d¢∈b・十1佐.一∵ .t t... ・∵1』・.t .1踵…f・・e』∈b+Vi・‘hr・rq・ence{九(x)}孕as・甲」頑!如゜t・鋤∫(r∼;興d
{九}姪皿jfbrmly c㎝vergeh島o∫bh ’eaiih 6十’5,. Wherご5fポan R−Ziibouhded sSiblset of Vi・F血r姫e頂oξe,∫ ]’sl.R−U一直ぴbr印εオable・ at eveTy R−v−jn‡とri.Qr,Pdη‘・x of. b十5, and ∫’(露)(y)ニP−u三lim∫fA(¢)ω(y∈世(の)・ 一 ゴ.三. 」 、』 、.『 ..,. }一...;.i….ピ..’.・...tぞ..・.‘㌦’....ご∼ PRooF. We 6nly ’plove ’the fblmel partl the latter paft fbllowS丘oni the similarw可⑯the・pro㎡OfThe㎝em 1・.、’ ..・・., .:・.1..・・.
Since、{み(6)}has・aP}hmit, tllere isω1∈チb(F)by Which{九(6)}is P−Caucby・ Choo6eω≒{Wk}∈尤oo(F)such that u1十u十ω1一くω. Given k, let m be such fhat 4W玩⊂,wk.、 Theh’thafe isηo・such!that噛痴(b)一プ三(b)∈照元一wm Vihenbv61 鍵)!≧力層≧no、. Let函∈b斗↓そ. Since x一ゐ、ξ…閲罵⊂E★(の,>we『see元by{h), that ther6 is 覗・一れ・(x・m)Su・hth・鴫(カ)(x−b)一蜘)(x−「b)E’・Wm’−Wm・wh・ne…ρ≧n≧n・ and y∈b十Vi. Put n2=max{ηo,η1}. Then, fbl any丘xed p and nl wit・h p≧’n≧ni, consideri皿g the map(Rl⊃){0,.1]∋θ}→.痴(b十θ(¢二b))一九(b十θ(x−b))∈Fand・PPIyi・9 th・・mr砿蜘帥…em・、w・h碑.、….、 ・ 。_ン、・,1.・’・
九(x)一み(¢)一(fp(b)−fn(b))・∈・W加二Wm(P一ω); 二SO…い ∴..、.. ‘.・T 1・.:.・. .㌦・、』・.…:∫’『..…胴一鍋.珊こ五θ・+二ご(詞…・:・..昌二1
三㌧∴∫. ゴ 1 ’ .・. T ⊂ 3(Wth tt’Wmう ⊂・Wk−Wk二ご.㌧!:∴. “・; .・.:, ば ・ 二 ‘ .’・.吊 ・ i T㎞・{fn(x)}i・p−Ca廟byω,・nd S6 it hぶ迦甲e p一ω一limit, d…t・d・by・f(x)・lf Si,。。 R.v.b。und。d、。b,et。f鵬血。h.㍉。e。6。6f穎碗蓋㍍。f’S・i、・R.’v.q。a、i・b。。。d。d. 籔qm thi・we c㎝Sρghr㊤・.η1鱒hρ.ab。v典・品s桓dePρnde耳t・f,X、.,q.・b,+β,ふ輪ML・HIKIDA
ni=’n、(m):=. n、(k);and then ∫(x)−fn(x)∈3Wm−Wlm(P一ω)∈Wk−Wk provided n≧n2. This shows.that・{ノ㌦}・is unifbrmly convergent to∫on b十5.、’ THEOREM 3.1}e‘∫:1)→Pandα∈1)1』stipposb‘ha‘∫js R一ψ一(iitlTerbh’tia61b・a‘ ・V・・y・∈D\{・}・wh・re・V=伍};and S・PPOS・ th鋤・舳W9てi)一(k)・h・ld・(i)Ther・紅c麺d・・∈み(F)・・φ顕∫((・+ゆD)⊂砕・)・
0)Ther・」S∼・u鋤h訓⊂(D−・)∩町(のa・d‘血・‘, f…opy.励九∈Vl,舌力・ map(R1⊃)[0,1】∋θ⇔∫(・+θ九)∈F:fs cOn‘Ou・u・㎝P,1].’(k)Ther・・.㎝』v−c㎝‘迦qUS五卿卿9・Etr(・)→雪㎝d・2ξ九(∬)鋤
‘haげ’(α十九」)(yi)−9ω→0(P−u2)f・r every{傷}Wit力㌧≠Oand九」→0(R−v) and every{防}∈Q(∋. Then∫is R−v−differen’tia’ ble atαand∫’(α)=・9. .P耳9・p・Lgt・μ・.∈・5(“}’).b・su・h鋤{9伍∩Ede(の)}、K u・一・・…ch…ρ wr{VVk}、∈チbo(F)such thaちμ1+u2+μ3<tμ..Let{㌧}∈2(∋and{λ」}∈.∧, Whereh」.≠0・q酔叫Ch・・‥>m脳{k,i,1}・p la・g・that 3顧⊂.照.・n岬凧但★⑩・
Th・輌㈹, th・・e i・,元・su・h th・t・λ」九1.叫㎝d∫’(叶ρλ轟)(ん」)「9(九」)∈Wmrwil Wh・n・・eり≧」。.叩d.θ.∈.[0,1】・恥・a・・y、fiX・d j≧ゴ0,、the m・p?;.(丑・⊃)/0,1]∋.θH f,(叶θλ∫九」)∈Fi・9・nti皿…、・n【0,1],㎝d iS R峰・?亘ti・H・・n(0,ユ)and 《 φ’(θ)=∫’(d十θλ元九」)()Lj・hゴ)∈λ」(Win−’Wm)+9(㍉ん」)(⊂’Ek(り).’ AS¢)([0,1])⊂Et(ω), We’Obtain . ・ .、. ...、 一 ・、’\.,.. ・・ .q(1).「∼ρ(0)=. f(q十)与㌧)一∫(α)∈λゴWm−W■(P一ω)十9(λ」㌧),thct、 ils.,・.∴・∵・一.、,....・.・ .−tt、・..。 ,.t,.._
λ;1[∫(a’1+λ」㌧)二∫(の.−9(λ」ん」)1∈・Wm−Wth(P一ω)⊂W、;Wkン ・” 1・. 「 ・ 二 ’・.’ ・ 1, ・ /. 」昌 ・ ・ . .1… Vi− . 』 .三 This ends the proo£ , . ..!i. ・.. 、 .,.’. :一.r qEMARK}1.(1}Ih The㏄el垣一3, ifふy㎜etτic,then(c)・is・superflu。us・・ttd the Conti加itY’(rf tlie map in(」)is require(1も血1y at’θi・0(c£[2]). In Theor6mS 1−2, it is easay seeh that’狽?ニconVetgences二fA(a)(ダ)L→・∫’(a)(y)(P」{£3)ahd fS(‘i’)(y)『→’∫’(¢)(シ) {P−u)’are tini{6r旨重㎡伍と士espect tσ310n・e反h R謝’bounded.s血bset of』E★(む)‘(a血d also :With teSpeCf tδthe孔ぴi誕e亘or l)oi血t x・・of b十5,桓. thi’lat’tとr C掴e).‘@… ... .ニニ ?Q)・()亘f.這ssumihg a I桓eaξranked連pace:to sat溺シ.てA.4)is’血eedless鍾the 6pace i8 sy垣血etriごand u LF・,a Lく剥br諏y O三fuhdamehtal seque血ce u. in the spaLce:ih t’his 157.158
APPLICATIONS,OF. MEAN VALUE THEOREM
case, R−u−a頃d P−u−convergences are coi皿cident. Thus if F is sym皿e垣c, tben the assumption that F satisfies(A.4)is皿eedless f《)r Theorems 1−3 a皿d for Theorems 4−5 give皿below. ExAMPLE(Dil旋rentiation a10ng Stob》s angular domains)・Let C be the complex plame. When O<ε≦∞,0<δ<π/2 and O≦α.<2π, we put B(ε)={z∈c:121〈ε}, V(ε,δ)={z∈0・z≠O, lzl<ε and 1arg・1<δ}∪{0}, γ(ε,δ;α)={e’az:z∈γ.(ε,δ)},where arg z is taken to be』−iπ≦arg z ’qπ. For e’=窒?@n=0,1,2,_, let
B。={B(ε):[1!ε】=n’}, ぬ={V(ε,δ;α)・【1/ε]=n,0〈δ<π/2,0≦α<2π}, whereη。o=.0. Then(0,{β。 U}タ})and(0,{Bn})become linear ranked spaces; we denote the fblmeτby CI and the latter by C. Cleaエly C, which is the’con}Plex plane with the usual topology, is symmetric, convex,(π一T1)and complete and satis丘㏄ (A.1°,2°,4)as a Hneaτra血ked sp㏄e. Yet, Ci is neither metriiable rior’topological:the non.symmet亘c hnear ra血ked space Cl is convex,(π・T1)and com回ete and.satiSfies (A.1°,2°,4).Note that究oo(C1)≠To(C1);fbr example, there isω∈To(C1)such∫that E★(ω)={0}.Let∫:D(⊂. Cl)→C, and letα∈.Dbe an R−v−inter輌OΣpoint of D for some v(…Too(C1)(for such v, E★(の=Cl necessarily). Then∫is】iしv−differentiable at a if and only if there eXists a linear map e:C1→C such that ∫(α+九」)ゴ(α)一2ω 一一一> 0 ((】R−b),i.e., in the usual sense) .h,・ f()rany seqllence{九」}inσ1 with九」≠Oand占」→0(1し∋, wheτe 6={β(1/先)}先∈ T。(C)(1/0=。。by definiti・n):One must remark that the linearity・f e means the real linearit}rl i.e., e(αzl+fiz2)=αe(zl)+βe(22)fbr any realsα,βand for a泊y 2、,z2∈C、. Of c・皿rse, e=∫’(α;v)in・the・ab・ve case. Now, let the power seτiesρ(z)=Σ;’=o Cnzn(bn, z∈0)have the.‘1adius of conveτgence,, r,0<r〈.−oo, where the. c.envergence is in C(to be precise, R−b− convergence).・Assume that, fbr so㎜zo・with.レol=r, the seriesΣi−o(n十1)cn+1堵 converges(in C);then the series £9e.o cn’z;also converges(in C). Put S={z:.同.< r}and 1)=SU{ze}. We regard D as a.’, subset ofσ1, and define∫:D→/Cto be ∫ω=P(z)on S and∫(2b)=Σ)こ二〇CnZ8.正et v={.γ(1/kiδo;(Σo)}烏・∈.S・(C1:), wLere O<δ。<π/2㎝dα。=arg・zO+π:The.set.z・+(γ(1/克,δ・;α・)\{0})is・cust・m副y
M,HIKIDA、
159
ca皿ed a Sto lz ’s angular domain(ω誠verteq zo and angle 2δ0).. Th飢・】塾ω=C1 (so v∈」陪oo(C1))a皿d D is R−−v−open・lt is obvious thatグ姪巳u,〈五危re皿tiable at every z∈Sand∫’(2)(九)=(.Σ二〇(η十1)cq+1zn)ん(九∈C1).、 Furthermore, by AbePs th…em, we see th・t(j)一(k)『 Ef・Th・0・b・ri・3 h old wi・h E:Ci,∬−C,。一。。皿d 9(h)=(Σ二〇(n+1)c砧1z;)ん;and 61early(i).hdds. Therefbre, by Theolem 3,∫ is R.v−differentiαble at zo and f’(zo)=g. The’tesult also f6110ws from Theorem 1 ・・21・becau・e it・ah b・・h・w・th・品・・r亘esΣ二・r・zn・・dΣ二・(・+1)・・+.・z” ar・ unif・・鴫・・皿・C・g・nl on zo+γ(1/i,δ・;…), wh・・e i>1/(2・c・・δ・)・it i・d・ar thgt the setγ(1/i,δo;αo)is R−v−bounded and R−v−gpen. Th・ab・v・a・g・m・4t i・ ・IS・apPli・d t・th・Di・i・H・し、se・i㏄Σ二・c・exp(一λ・勾 (0 ≦ λo < λ1 < … < λn < … → oo)having the “abscissa of convergence,,ノ1, −oo〈ノ1<oo:We omit details. REMARK 2.(1)We temPorarily ca皿a’ linear space(over R)aguαsi linear ranked space if it satisfies(E.1),(E.3),(E.4’)and(E.5’)(c£ Appen(五x). Theorems 1−3 remain valid if we let E be a quasilinear ranked space. Thus, in the above Example, we may take the quasi lineaロanked space(0,{.V})f〈)I thとspace C1, Where W=VoU{0}a皿dV =Vnfbr n≧1.
(2)The fbllowing condition(A.1)on a linear ranked space E was giv6n in国: (A.1)B)reach v={Vk}∈万(E)there is ko such tllat Vk。⊂E(の. It can be shown that 1 iA.1)is equivale皿t to saying that, fbl each v∈冗(E), if{場}∈Q(v), then thele is n such that the set{hj:」≧n}is R−v−bounded..The ”space−Cl in the above Example does not satis{y(A.1);so we see that there exist U∈1巧)(C1)and {んゴ}∈9(u)such that, fbr every n, the set{hj:ゴ≧n}is not R;u−b6unded, since 2(U)≠0・bvi・usly. 2.Partia1 derivatives. As bゆre, assume throughout this section that F is a (π一T1)1ineaエranked space satisfying(A.4). Let E a皿d G be Unear ranked spaces. Letσ:5×世(ω)(⊂E×G)→F, where w∈T・・(G)and・E×Gden・tes the pr・du・t hneaロanked.space()f E and G. Let b∈5be an R−u−interior pOint of S for some u∈万(E). Then g is sa輌d to be R−u一 んyp・c・ntinu・tes at・b, if there existsω・∈T・(F)such −that’ 9(b+九ゴ,蛎)−9(b, yj)→ 0(P:ω1)fbr every{九」}with hi→0(RFu)and evely{防}∈9(ω)(cf.(e),(h)and (k)of Theorems 1−3). Nom here to’ the end of this sectio叫1et E1 ×. E2 be the product・五nea’ranked space of linear ranked spaces Ei and El2 ’and ’assume that: :㌃.ジ.D⊂El×E2;
160
APPLICATIONS・ OF MEAN VALUE THEOREM
二了:・D−→F;』’.〆 』 ’ 「穀」:但浪.ざvΣ希}ξ端・(Ei’x Ei)i『 一 ..、’ v、≒{v,,A}』∈み(E、),.v、〒{v2,k}∈E.(E2); .’ 豆一(卯・)、∈.D・鋤C陣巳ρ一inゆ・p・i・t・fD・ . .D・={X・∈E・;・.〈・・…)∈ρ}, D・={9・∈E2・(….・・)∈D}・−If・the血・p D・∋玲∫(x・,C・)鯉i・R−Of・繊・ehti・bl・鋤・〒α1坤r・w・
d・n…‘・h曲rd・舳・ive」b・∂・∫(α;の,Cr brie6y’by∂i∫(q);・nd’・訓1麺・“(挺醐晒・IR一輌1・・興〃垣(碗九卿ect・t・’九ゆ5舌』晒・ble)・The魎l
R二ρ一dとW・励・∂、∫(d;’りi・d・血,・d・滅輌』If∫誌且・−d品・皿ti・b16 at・, th・n ∂、∫(・)=‘O、f(d;0)』(‘1,2)”exiS’t・hd:㌦− 、 一∫’(・)(露1J、X2)=∂・∫(・)(・・)+∂・∫(司(X・).』..、・.、 wh。,e(X、,鋤∈Pt(の=Ek(V、)・恥、).1C・nv・・』ely ’i・h酌ゼ..‘…』ゴ・T…R醐4・be‘Db・R−VT・PC・・.飢d lrげb…一.孤d・・敏(A4°)紐d
(A2°). S・pP・・e‘h・餓∫(・)=O・f(x;∋(‘=1,2)・Xi・‘・t・卿・eρ皿dεh・励・ fbμo町ng(a)一(b)力ρ14:、,.t・. .. ・・ . 、. tt.・ ’f・).Th・・鋼・た・opd u・∈f・(F)鋤伍・げ((・+防,・・×. V・,k・)∩D)⊂E★(μ1)・ (!).Thαe」・1;.r・・励・砺,・×巧,・⊂(D−・)∩E★@)㎝d伽‘・f・・a・y五x・d (h,,h2)∈V・,1、、xV2,・舌五・卿(丑・⊃)[0・1D‥∫(・・+θhi,・a2+九・)∈Fi・ con¢」ηqous on .[0,1]・、 1f∂・∫,刷h・皿・p∂・∫・D×.醗ω∋(・,y)戸∂・∫(・)ω∈F,」・畑吻P㏄・頭皿u・・S at¢=α,‘hen∫js R−v−differe皿tiable a‘α. . . . PROgF・P・t・(y,・)=∫(0・+y…+・)一∫(・・,・2)一{∂・∫θω、†∂・∫(・)(・)], wh・・e (y,2)∈(D’一・)∩y(・);・hd w・it・・(s):・)’=「・、ω,・).+・、(・)減ρ・6 ・・(y,・)=∫(・i+y,・・+・).一∫(・・,a・+・)一∂・∫(・)(9),.f ”.s2(z)』」∫(αゴ,α2+z)一∫(α・,α2)−aア(α)(z)・』 Let u2, u3∈フ㌔(∬)be su匂h that{∂1∫(α)(γ輌,夫∩E★(v1))}.Kμ2−u2 and∂1∫(α十hj)(防)一 ∂、∫(・)ω→0.(P叫㊤・e卿{九」}with九ゴ「・0々)・孤d・V・ry{yi}∈Qω;・and besides let u4∈戊㌃(∬)be such thatλ;1s2(λ」ろ)→0(P−u4)f‘)1・eVely.{ろ}∈9(ρ2) an4・eyery{λ」}∈A−, Chooseψ.∈戊るo(F)sllch:that ul十u2十μ3十u4.rく.・ω・Then, given{(yi,ろ)}∈9ωand・{λ」}∈∧,・ applying ,the. mean.,yぬe.th《ゆre叫・we see λ;1・・(λ」坊,λ」ろ)→0(P−w);・nd th・・ef・・eλ;1・(λ」坊,λゴ・」)→0(P一ω)・(We・mit details.)M.HIKIDA・
We sh品1 denote by.v輌×巧・the血1ndamental sequence{Vi,先×巧,先}斥∈Too(Ei×Ej), wh・・e‘,」=1,2(n・t・ny(・‘X.汚.)=・蜘輌)X世ω)・ Second−order parti品de㎡v延ives can be ldefined as follows. Let D be R一勿一〇pen and assume that∂1∫(エ)=Oi f(x;’v)’eXists at every¢∈1). Then∂2∂1∫(α;の, the 5ec・nd−order.ρ・伽’R−・−derivat劫e㎡∫吻, i・a〃・Xv・・c・孕tinu・田・bilinear map o茸Eキ@2)×E★(v1)into・F such that the{bllow輌ng holds:theτe is u∈フ㌔(F)Such thatλ;13(λゴ九」)(防)→0(P−u)fbr every{㌧}∈Q(v2), every、{防}∈,Q(v1)and ev− ・・y{λ元}.∈.A坤・・e3(九)ω=∂・∫(・・,・・+ん)ω一∂・∫(・・,a2)ω一∂・∂・∫(・;v・)(九,9) ((h,y)∈i((D2一α2)∩Ek{v2))xE★(㊨1ルThe other second一ρヂder partial R〔vr.derivatives a,ajf(α;∋(‘,」=1,2)are defined smilarly. The nOtion of R−v−differentiabihty of ∂1∫atα, oT’(∂1∫)’(α;・∋the R一妙一derivative/o∫∂1∫α2α, is㎡sg obtained by 1epla,c− ing, i皿・the definition. of∂2∂1∫(α;句, the・sylhbols“∂2∂1∫(α;v),,,‘‘v2,,,‘‘s(九)(y),;and ‘‘c2一α2,, with tlle symbols“(∂1∫)’(α;の,”‘‘v,,,.‘‘3°(九Xの”an(11D一α,, respectively, where 3*(h)(y)=∂1∫(α十九)(y)一∂1∫(α)(y)一(∂1∫)’(α;∋(九, g). The R−v−derivative (あ∫)’(α;v)is de五ned similarly」 THEoREM 5. Le‘Dbe R−v−qpen, and le‘Fbe cbh”vex and sa‘js」ヶ(A.1°)and (A・27)・.Ar・輌晦‘O・f(x)=a・f(・;の(i 1・2)・ガ・オ・』・胆四紐d(・)三(b) of Theorem 4 hold. (1)S・PP・se‘力a励・・e」s∼、 s・(カ‘ha‘Vi,己1×V2,1、⊂(D一α)∩廿(㊨)紐ぷ鱈、血 a刀[y五xed(hl, h2)∈Vl,ll×レら,’1,‘力e mal)(盈1⊃)【0,1]∋θ⇔∫(α1十ん1,α2,十砺,)∈R 」sc・n‘」皿u・us・n[0,1】・1f∂・f and a2f are R−v−(k’fferentia’・ble・a‘α,伍㎝鯵∬・ト ∂‘aゴ∫(α;∋(i,」=1,2)eXist. . ・ ,②S・卿幽3舌舌』・・e痴・P・岬dω・栖(F)(‘1,2)・uCh th・瞬・⊂E(・・)
・・d・ f・r each i・a∫(司(V,1,・∩}i}k(・・))⊂E,r(ω油・・y x∈(・+V・,・巧,・埠D・.S叩} ‘h・‘∂、∂、∫(・)=∂」∂、∫(・;∋斑・‘・at・ev・・y・x∈D;a・d・叩P・姪ε砧a莇・・e返Z、 s・・h ‘ha‘γi,12×V2,82⊂(1)一α)∩E★(∋and‘ha‘,」br any五xed(ん1,九2)∈Vl,12×ルら,12,奮力e口3丙P (Rl⊃)【0,1DθH∂・∫(・・+九・,α2+θゐ2)(九・)∈Fisc・n‘」加…㎝[0,1].∬∂、∂、∫, as‘血e ma¢)∂2∂1∫:D×Ek(ti2×vl)∋‘(エ,z)ト〉∂2∂1(¢)(z)’∈F, js R一ひ垣pocOn‡」ηuous a‘虚=.α,・仕en∂、∂2∫(α)=∂、あ∫(α;∋exis‘S. .’ ・.. Moreove]ら」孕(1) alld(2)7 va∋have ∂・仇f(α)(x1,x2)=あ∂、∫(α)(露2画)・・一 .・ ・ f‘)r(¢1,X2)∈Ek(Vi)×餅(v2). i ’ PR・・F・(1)・By・th・f・・t・t・t・d b・㊤・e The・r・叫⑭∫(・)・傾・r・by 鍋∫(αXy・,Y2)=(∂・∫)’(・)((Y・,0), y・),161
162
APPLICATIONS OF、MEAN V肌UE THEOREM
∂2&f(α)(z、,z2)=(∂2∫)’(α)((0,z、),z2),・』’ :’ ∂、∂2∫(αX¢、,x2)=(∂2∫)’(α)((Xi,0),¢2),『 ∂、∂、∫(の(・、,・、)=(∂、ノ)’(・)((0,・、);・、), where・(∂輌∫)’(α)=(∂げ)’(α;の(i=1,2),(Y1,Y2)∈Et(vi)2,(zl,z2)・∈世(v2)2、 a皿d (¢ユゴ.x2)∈Es「(v1)xE★(v2). The proof of∂1あ∫(α){¢i,¢2)=∂2∂1∫(α)(x2,¢i)is a皿alo. 9・us‘t・that・f[2,・Lemma 2], and・iS・theref・re・mitted・ (2):Let.ω3∈チb(F)be such thatあ∂1∫(α十¢」)(ろ)一∂2∂1∫(α)(ろ)→O(P−・ ω3)for every{ち}with¢」→0(R−∋and every{zj}∈2(穀2×vl). Chooseω・= {Wk}∈∫bo(・P)such that ul十ω1十ω2十ω3舗くωゴwhere ul is as in(a)・ Let {ん」}∈2(v、),{yi}∈2(v、)皿d{λ」}’∈A. Giv・nk,・』・・ems・1・・g・th・tm≧ max{k,ko,1,12,ρ, q},3Wm⊂Wk and Wm’⊂Et(ω), where溌o a皿d l are as in(a)and in(b)respectively. Then there is 」”such that・ λ」九」∈Vi,m, λ」坊∈v2,… . 、 . 砺∂1∫(α1+θλ」九」,α2+ξλ豆yゴ)(yゴ,九」)一∂2∂1∫(α1,α2)(坊,九ゴ)∈VVm−Wm, wheneverゴ≧ゴ’,θ∈【0,1]dndξ∈[0,1】. Fbご」≧ゴ’. Then, si皿ce yi∈E(vi), {Y,n}n∈2(v2), where Yin=防for all n. Choose{μπ}∈Asuch that O<μn≦λj for all n. ThLe皿 あ∫(α、+,λ」九力α2)(yゴ)一∂2∫(α・,α2)ω =μ;’[∂、∫(α、+λ」九ゴ,・、)(μ。防)一あ∫(・・,・・)(μ。防)】’ 一μ;1[∫(・・+λ如・+醐)イ(α、+λ」九」,α2)三∫(・・!・・+卿+∫(・・i・・)] +μ;1(・、バ32,。) where・ ・・,。=∫(・・,α2+μ。Y」)一∫(・・,α・)raf(・・,・2)(醐), 32,。=∫(α、+λ」んゴ,α2+i・。Y」)一∫(α、+λ」ん」,q2)一&∫(α・+λ」九」,α2)(μ。y豆)・ Put sn=sl,n−s2.n. Since sn∈E★(ω)andμ;15n=II;lsl,n−iiFls2,n→0(P), μ;18n→0(P一ω)by(A.2°). Choose n such that t.. λ;1μ;15。∈Wm−Wm, and fix it. Define 1ユ:[O,1】(−⊂Ri)→,F’by ∼ρ(θ)=∫(ai十θλ)ノ弓;α2十μ鴨シ」)一・f(ai十θλ」九元,α2).M. 」・H】KIDA Then lρis co皿timlous on・[0,1】, and is R−d三ffe肥皿tiable on[0,1)and 9’(θ)=∂、∫(・i+θλjゐ刃・、+醐)(λ」九ゴ)一∂、∫(・、+θλ」九ゴ,・、)(λゴ九」). Fb【θ∈[0,1), a浪d defineψ:【0,1】(⊂丑1)→Fby ψ(ξ)=∂1∫(α1+θλ」九」,α2→一ξμπ防)(λ」九ゴ). Thenψis continuous ol1[0,1], and is R−differentiable on[0,1)a皿d. ψ’(ξ) = ∂2∂1∫(α1+θλノ,ゴ,α2+ξμπ坊)(Bnyi,λゴhj) ∈μπλ」(VVm−Wlm)十μ九λゴ∂2∂1∫(α1,α2)(3ら・,九ゴ)ピ
Hence
9’(θ)=ψ(1)一ψ(0)∈μπλゴVVm−Wm(P,ω)+μπλ」∂2∂1∫(α1,α2)(防・,九ゴ), sinceψ([0,.1】)⊂E★(ω)andψ’([0, i))⊂E★(W), Therefqre q(1)−9(0)∈μπλjWm一ワVm(P一ω)十μπλ」偽∂1∫(α1,α2)(防・,hi), since y)([0,1])⊂E★(ω)and g’([0,1))⊂E★(ω). Conse(luently we haVe λ;1[∂・∫(・・+λ」ゐ」,・・)(y」)−af(・・,・・)(防)] =λ;1μ;1(q(1)−9(0))+λ;’μ。1 lsn.. ’ ∈ Wm−Wm(P一ω)十Q∼∂1∫(α1,α2)(yj,九」)十VVm−Wm ⊂Wk−VVk+∂2∂・∫(α・,α2)(防・,九∫), that is, λ;1【∂・∫(α・+λ」九」,α2)(yi)一∂・∫(・・,・・)(坊)−02∂・∫(・・,・・)(防,:λ」んゴ)]∈VVk−Wk P頑d・dj≧プ・Thti・∂・Ojf(・)・Xi・t・a・d∂・&f(・)(九, y)=∂・∂・∫(・)(y,ん)((九,y)∈ E★@1)×E★(v2)). REMARK 3.(1)The hypotheses of Theolem 5(1)imply the R−v−differentiabili−ty of∫atα. This fbllows from Theorem 4, since the R−v−dif』entiability of∂1∫atα impli題the R一ぬypoconti血皿ty of∂1∫atα(c£・ [2, Le輌1D. (2)In the particular case where. .Ei=E2=RI in Theorem 5, all∂;aif{α)are ・ymm・t・i・and∂、あ∫(・)=02∂、∫(・).1・Th…em 5②, th・as・umpti・n・“V、,。⊂E(v。) for.someρ”is need}ess i・f v2十句く・v2.1皿Theorems 4−5, if・ v is symmetric, then (b)and the assumptions of continuities of the mapsθ←⇒・∫(α1十、九1,α2十θ九2). and163
164L
APPLICATIONS OF MEAN.V肌UE THEOREM
θH∂1∫(α十九1,d2十θ九2)(九i)a【e・supe㎡luous.(c£』【21). The thθorぬs・also remaih’v棚
チ昂㎝d跳rΨ〔’hneaHC岬lipg£es,.(cf・.Rem〔k 2ω)・
3.Note8. In t垣s sectio皿we show that some known theorems fo皿ow f【om our reSUlts. L・txb・a・eal 1°c凪y C・pv・?[・p反・w㎏・e tCpglf..gy iF i・duced』−t・bl・ sepaエating famiy of semi一皿orms.1卜‖π(n=1,2,._)stitis{ying ll¢1』≦11xlln÷1(x∈x): we tempolar丑y call such q space X・a《lc碗η施b「y 3eη2i−nσrmed spαcε..:Let/V(X>・= {γ(・,・)・・=1・2,・∵・・>0}・輌・γ(・・r)一、{x∈.X・1国』〈r}・.N(X)i・a.bas・ f()rthe neighboエhoo(1’ systein 6f O 6f X. AS in[4;. Rk血泣k l], put.}㌔={γ(η,ε):ε> 1}U{X}a皿dVh={γ(れ,ε):[1/ε]=n}五)r・n…=1,2∴.∴.Then(X,{Vn})becomes a linear ranked space;we de皿()te it by Xr. Obviously X.輌s symmetric, convex,(g−T1) a皿dsatisfies(A.2°,4);and as E(の=X.{br any v∈fo(Xア), foo(Xr)=fo(.Xlr)and X.satisfies(A.1)(cf『Rema【k 2(2))..&血the士more,ち→¢in}X迂and only if¢」→x (R)i・Xr・and X is c・卿1・ピi!皿日.・nly if.苓ir・・頑・tρ1... 、.. Let・X・and Y be c・u批棚y Se血一h・・ined’・P・k b・j and∫・.D:(⊂X)→Y, Viti6i・Di・・p・n・Tak・3Ψ∈石(X・)1・The・,ノ. is.興rε雌麺典・t・四(f・‘五・・ense
of[5])jf and o且iy if f:1戊(⊂X.)→};js R−v−(fifferentiable.aεα;and‘hen‘五e Fr(尭heオ and the R−v−der’is庖‡fves.(if’f.atα.arb.c(jiロcident. The.‘{(加1y if,, paxt、vas Show血in tlle proof of[4, Coldlaly 1]. Tb plove中e‘「坪,.paエt,putア(h)=∫(α十九)一∫(α)一∫’(α)(九), wh・・e∫’(・)is・h・R−v−d・ri・a・一∫…輌h is㎡・6c6n・iW面・・a・・…th・m・p∫’(α):X→γ.Assume f iS皿dt・騰het品とenti沁le atα.・Then』e e垣st a
・equ・nce{λ」}6f・e品血血b・・s withλ」≠o㎝4λ元→0皿d a託qu・hce{㌧}・f p・int・ of some bounded subset of X suφthat厚1 r(λゾリ).hOip y:we.may assume Aj>0, since the me血bels ofノゾ(X)a皿d/V(γ)ale bala皿ced. Since we liee{ん」}∈9(∋, it foll・w・丘・m th・R−v−di{fe・e・ti・bility・・f・f at・th・tλ;1・(λ」1与)→0(R)in・Y, ’ iC£;識興1(・2));1麺d・?λ;1・(剃?°叫・.cg加ψigtign∵・・../..・
Fro血the above observ欲ion and Remark 1(1), Theorem 2 yields COROLLぷy. i.缶e‘. X㌧aO∂γ:b6.・6睡鋤s・㎡こn・ith6∂』Spaftt・,・吐e踵Y垣 complete. Let プ』:1).(⊂ X) → γ (n = 1,2,...) be F)6che‘differとntiableと)n 1); where D.」sφ言㎝.…SUPP・se・鋤ち1 for・ ・some.α.e1),.伽β吋:ti・nεe仏(α)}・・nvetge・; and sφウδse:‘止a‘吋力ere.語γ∈.XV’ iX)・・suChi that.γ三⊂.D.一αa頃d..th6 fbllowing’一(*) h()ldS:(・)8輌ve皿σ∈4r(y)・・皿d a・b・・血(led. sqbOet Bl’.・f X3.£力ere fs句.S諏力・』ε fk−(X)(九)一ミプ1(¢)(九)∈・σ一. ttheneltier.7η..≧n.二≧.noj・¢’∈α・十.V..and h疋…βそThen,・fOr each毎.∈口十Vプ雄eseqロence・{fn(る)}・has/a’.五miち.de取0‘日d.byプ(¢);・{fn}{jS U皿輌fと}rmly 。・riVetgent・ to f・ ori『eぬb6ロロ{ied’subSbt,S(㎡・α:+V;・and f.isFt(khet−(紐】n掘able 話e岨γ輌血¢e加、画丑口・(ぜ.8,..鑓d∫{(X)㈲=.hm』」旨(司(九)(九eX)(,this eenfergence、...