SUT Journa1 of Mathematics
(F()rmerly TRU Mathematics) Volume 27, Number 1(1991), 1−15ON HIGHER ORDER DERIVATIVES IN DIFFERENTIAL
CALCULUS BY THE METHOD OF RANKED SPACES
MAsATo IIIKIDA
(Re㏄ived Maエch 15,1991) Abstract. We define the notio皿of higheエorder derivatives and give Taylor,s formllla i皿differential calculus i皿Uneal ranked spaces with皿o皿一symmetric ple皿eighbolltoods. 1980Mαthematics 5%bゴect Classification.46A99,58C20. Keywords. Ra皿ked space, No皿一symmetlic pエe皿eighborhood, Taylor,s fbrmula. We make in this四)er a further study ofl Nagakura[5], i.e. we define the notion of higher order derivatives and give Taylor,s formUla in di丑ierential calculus i皿linear ranked spaces. Our standpoint of developing a theory is to work constructively in situations of generality, so we wa皿t to keep being in the category of given.spaces a皿d to avoid complications as much as possible. The investigation made in[5], which was do皿e by the method of ranked spa£es, sUits the standpoint. Thus the method taken in this paper is different from those of other theories of differe皿tial calculUs in linear spaces:Apreneighl)orhood of the origin of a linear ra皿ked space is neither open(in the toPdogical sense)nor syInmetric, and need not abSorb all points of the space;the convergence in a linear ranked space is de丘ned by means of a fundamental sequence of preneighborhoodS, Plainly speaking, a se(luence of points is required to converge to a point along a given path;a皿d so the、derivative is not reqUired to be defined on the whole space. Furthermore, we do not treat a“space”()f mUltthnear maps(between 9iven linear spaces), since in general the“space”of such maps is皿ot in the category of the given spaces. In view of the results of[5]and of this paper, it seems to us that the method pf ranked spaces is effective to revea1 the real nature of matters;f‘)r example, we see that. Taylor,s formula is closely related to the character of fundamental seque皿ces of pre皿eighl)orhoods(and so to that of convergences). 12
HIGHER DERIVATIVES IN LINEAR RANKED SPACES
Throughout this paper, a‘qinear ranked space,, means a linear ranked space of[5], .and we. con{blm CurSelves to the ter㎡nology and{he notatiol1S gf[5];yet, only{]or the “P麺r・頂・・gと・r・”、・nd thC、“P−i・ゆ・輌,”w・ .adgPt・中・㊤皿gwi・g m・di丘・、・tiOn・・ Let{Vk}be a O−furidaniental seqU6nce in a lineal ranked space. E. A sequehce {エ」}of points of 1ヲis said to l》e parα一{Vk}−converg.ent to x∈E, in symbds⑳」→¢ (P−{Vk}), i{there e垣sts a fundamental se(111ence{yi十隆ω}(k(り↑o◎)in E such that¢.∈∩(祐十Vk(り)and that, fbr・any i”there isプsuch・that gj∈yi十Vk(りfbr all j≧プ.Apoint x of a subset 1)of E is called a P−{Vk}−interior point(ゾ1)if, fbr a皿y f・ndam・nt・1・eqUen・e{Zi+Vk(i)}低)↑。。)ln E with x∈∩(・汁Vk(輌)), the・e i・i such that Zi十Vk(‘).⊂1λ . . 、 . ・− With these mOdi丘cations, the results of[5】remain valid. In ’the above,・if yi=¢ f・・all・i, th・n{・」}i・・said・t・b・B伍}一・・nv・・gent・t・・, in・ymb・1S¢」→x(R−一{Vk}), as was defined in【5];and if z‘=xfbr all i, then x is called ah R.{Vk}−interiol pointofD.
0.Notations. We denote byフ㌔(E)the set of al1 O一血ndamental sequences in a lineaロa泊ked spate E:meinbers{Vk},{砥},・etc. of −o(E)are frequently written as v,u, etc. f‘)r l)revity;and we put foo(E) = {v∈戊㌔(E):一.the otigin O is an R−v−interior point of E★(の}, A=.{{λ♂}:λ」>0.and.)1元→0};and when v={Vk}∈}チb(E)and h∈E;we put
9(v) eing R部一quasi bounded means thatλ・h Pis a non−negative integer and Ep rank(…d space(the product linear ranked space of li皿ear ranked spaces is defi same manner as in{4])sp.ace, we frequently denote the sequences{Ak土Bk}by{ノlk}士{Bk}Iespectively
and the.notation{Ak}く{Bk}means thaほ)r any k there is .k 〈h>P where ’{㌧}b ([5]), −. REMARK. If{Vk}∈チb(E), then ・(le(り↑。。血ea皿s k(i)≦k( tllat Vk−Vk⊂E★(∋ {{㌧}:《九」}is an R−v−quasi bounded sequence in、房}, ρ臼mes伍x…・鳴・(∈万(五w)), 、
,tlme8 (一h,_,h)(∈助, 3」→0(R−∋長)revery{λ」}∈A =」D×….x E(ρtimes)is the product linear ned by the .Moreovet, fbr sequences{Ak}and{B鳶}of subsets of a linear ; ’such that A⊂B友. {Vk(‘)}∈万(E)五)I every{えω}withゐ(の↑OO i十1)→∞).If㊨={Vk}∈」弓oo(E), then・the元e is1‘such ;hence the origin is then a P−v−interioτpoint of E★(の, and so へM.HIKIDA・
3
B(のis P・v−・畑, that is, every p・int・f.Es’(v) is P−v−interi・r p・i皿t・f Ek(妙)、 F6r皿y・∈乃働W・bav・蜘り=町・)×一…・恥)(ρti聴r);・・(・・,・∵・rl・.)∈蜘り
implies(x・(1),…,Xr(ρ))∈E★(vP)&)I every mapアof{1,_,ρ}into itself. R㏄all that, as・was・defined・in【5], when・u={Uk}∈T。(Ep), E(u) = {x∈㌧EP:fbr. each k there is E★(u) = Span E(u). λk>Osuch th誠1¢∈A,k Uk}, Througllout the. fbllowing sect輌ons 1−3, E and F stand fbr lineaエranked spaces,’ and・D・stands・f・r・a・subSet()f E;and we assume that F always. 唐≠狽奄唐?奄?刀Ethe. @c・nditi・n (A.4)of[5](c£Remark(2)at the end of the section 2): (A.4) If{Wk}∈乃(F)and if a sequence{¢先十階}(xk∈F)has the non−empty i・t・・secti・n・th・n th・・e i・{k(i)}(k(i)↑。。)…hth・t{xMi)+Wk(・)}輌・a血・d・m・nt品 sequence and that⑳」+W」⊂xk(‘)+Wk(‘)whenever j≧k(i+1)・ 1.Higher order derivatives. Let v={Vk}∈fo(E). A map.∫:1)→.F iS said t6 be妙一con・tinuousα‘α∈1)if, f()r any fundarnental se(luence{xi十Vk(↓)}(k(り↑oo) i・Ewith.・∈∩(xi+Vk(り), th・・e i・u∈f・(F)・u・h th・t{∫((xi+Vk(、))∩D)一∫(・)}く u−u;and∫is said’to be v−continuous(on 1))江it is v−continuous at evely point of D. Thus if∫is v−colltinuous atαfbr each v∈乃(E), the皿it is continuous atα (in the sense of[5D;in particu1西r if vl一くv鮫)r any vl∈」にb(E)and 1ヲsat姪fies the fbllowing condition(A.4°), then the v−continuity of∫atαimplies the eonti皿uity of ∫atα: (A.4°) If{Wlk}∈fo(E)and if a seque皿ce{xk十VVk}(¢た∈E)has the hon.empty intersection, then there is{k(り}(k(i)↑∞)such that{xk(‘)十Wk(輌)}is a fundamental sequence・PRoPoslTloN 1. Le‘L:廿(v)(⊂En)→Fbe a mUltilinear map, whe肥v=
{Vk}∈漏(En).∬Li・v−・・nti・・・…t・th・㎝④〈0>・,‘th・n・th・・b i・u∈f。(F)…h ‘ha‘{L(Vk∩E★@))}rくu−u. ConverselM, if su6h u exis‘s a直d∫f㊨∈免oo(En),孟hen ‡here isω∈」%(F)such‘ha‘{L((Vk−V,)∩E★(v))}一くω一ω;1}om t五is jt fb皿ows ‘h・‘{L((xi−+Vk(‘))∩E★(v))}.くω一ω血皿y£皿d・m・n‘al・eq・ence{Xi+Vk(輌)} (k(り↑◎o)in En w“h〈0>n.∈∩(Xi十Vk(《)), so L●then v−con‘fnuous a¢〈0)n. PRooF. Assume{L(Vk∩E”(v))}・くu−ua皿d v∈foo(宮). Chooseω∈;o(F) such that. 2論tilrres − U十一・一←U rく ω. . ・4
HIGHER DERJVATrVES IN HNEAR RANKED SPACES
Then, since Vk−Vk⊂E★(v)for some k, we have{L((Vk−Vk)∩E★(v))}一くω一w.PRoPoSITIoN 2. Le‘L:酢(v)(⊂En)→Fbe mu1‘∬mear, where v∈fo(En).
5upPose』‘Lis u−c・ntinuous at the ori8i’n. (1) If n=1,‘hen L js v−co皿‘f皿uous oll E★(の. (2) If h≧2and if either v∈チbo(En)holdS or E satisfies(A.4°), then L js v−continuoロs on E★@). PRooF.(1)is obvious. We prove(2)only for the case n = 2;the other cases follow 丘om the same way. put v={Vl ,k×V2,k}た;we may assume vl={巧,k}∈fo(E)and v2={V2,k}∈チb(E)・Fix(α, b)∈E★(v)・Since L(x’,y’)−L(α,りニ・乙(x’一α,yi −b)十 L(xLα, b)十L(α, y’一のf()r(〆, y’)∈E★(のand since E」r(∋=E★@1)×E★(v2),it sufHcesto show that the maps B(vl)∋x→L(x,6)∈Fand E★(v2)∋y→L(α, y)∈Fare
vl−and v2−continuous at x=Oand at yニOrespectively. Furthermore, since L is
bilinear on E★(の, it is enough to assume b∈E(v2)andα∈E@1). Let{xi十Vl,k(り}㈱↑。o)be a血ndamental sequence in E with O∈∩(xi十Vl,k(り). Put yl=Vll ,k(D andγ;’=レ),k(の. Letλ‘>0(i=1,2,...)be such that b∈λ巨y;’. Choo6e a suもsequence{i(ゴ)}of{i}such thatλ輌(ゴ)Vl.(」+1)⊂γ{(」). Assume v∈ フ㌔o(E2). As L is v−continuous at(0,0), there is u∈fo(F)such that{L((V;× τノ;’)∩E★(∋)}一くu一ぴ Choose ul∈チb(F)such that u十u一くul. Then, since Vl×γ(’一γ1×yi’⊂E★(∋f()r some i, we have{L((xi(」+1)1十γ1(元+1))∩E★@1),b)}」く ul−ul。 Assume next that E satisfies(A.4°). Then, since 0∈λ・(」)(Xi(」.・)+γ1(」.、))⊂λi(」)%.・)+γ;(」), we can find{ゴ(の}so that{λ‘(」(2))叫」(り+1)十γ1(ゴ(の)}t is a fundamental sequence. By the v−continuity of L at(0,0), there existsω∈」にb(F)such that {L(((λi(、・(t))知(t)+・)+v(・(」(η))×畷」(2)))∩E“(の)}2くω一ω・ From this it fbllows that{L((Xi(ゴ(勾+・)十VI・(」(2)+1))∩匪(vl),6)}t一くω一ω・Thus, in either case, we see that the map x→L(x,b)is vl−continuous atωニ0. Similally the map・9→L(α, y)is v2−c・ntinu・us at y=0. Let D be R−v−open for some v∈戊㌔o(E), that is, every point of D is an R−v−interior point of 1)工eげ:1)→Fbe a map, where F is(π一T1). We define f to be…llw∼xys O times R.v.differentiαb「eαt every point of、0, and put∫(o)=∫. For t}le integerη≧1, we de丘ne, by recurrence on n, theηtimes R−v−differentiability of f as fbllows:fis n 舌脅ηes R−v−d−ifferentiαbleαtα∈1)if it is n−1times R−v−(田』entiable at every point of D and if there eXists a v”−continuous multilinear map f(n)(α):蹄九)(⊂En)→FM.HIKIDA』1・
such that the map.rπ,. give皿by ・。㈹(・)=∫(π一1)(・+九)(・)一∫(毘一1)(・)(x)一∫(烏)(・)(九,x) ((・,x)・((D−・)・軸・E*(・・一・)), satisfies the f()llowing: 』. (†) There is u∈万(F)such that ’λ;1・・(λ」ん」)(・・)丁゜(P−∋ f・・ev・・y{hj}∈9(の,・ve・y{・」}∈.9(v炉1)aPd・v・・y{㌧}∈A・ And f is said to be n tirnes R..v−difierentiαble(on D)if it isηtimes R−v−differentiable at every point of D. R・m・・kin止・ab・v・that th・m・p∫(n)(・)i・uniqu・ly d・termin・d・in・Ek(の・it is calIed the R−v−der肋α舌iηe〔)f ordεr n of f at a. We sometimes say that a sequence {¢」}of points of a set X is eventually in a set 5⊂X・if there is J” such that xj∈5! f‘)rallゴ≧プ. Remark that if v∈戊㌔o(E), then.evely{九」}∈9(のis eventua皿y in E★(∋. The fbllowing conditio皿(A.1°)will be丘equently assumed below: (A.1°) For any ul∈チb(F)there is u2∈克oo(F)such that ul K u2. LEMMA 1. S叩Pose that∫:1)→Fisηtimes R−v−diffe肥ntiable a‘α∈1), wheren>1、Then
(1)There exist u’∈フも(F)and u”∈チ6(F)such that,9ive皿{hj}∈Q@),
{¢」}∈2(vn−1)and{㌧}∈A, ・ ∫(n)(α)(λ」㌧,ち)−7>0 (P−ut), フ ∫(外一1)(α十λ」ち)(¢」)一∫(π一1)(α)(苫」)−7>0 (P−u”). 」 (2) If F satisfies(A.1°), the皿‘止ere isω’∈.チb(F)sロc血‘ha‘, give皿{九」}∈2(v), {・」}∈ρ(vn−1)紐d{㌧}∈A,‘h…q・e・ce{∫(n−1)(・+λ轟)(・」)}」」・event・ally fn E★(ω’);丘om this it‘hen」b」Uows‘ha‘‘here eXis’tsω”∈チb(F).such‘力a‘,91’ve皿 {んρ,」}」∈2(v),{ち,」}」∈2(njρ)and{λ,,」}」∈A(ρ=0,_,n−1);someゴ1 can bef(川nd in such a way that . ..・ ’
.i{’)(α+λρ,」んρ,」)(rp,,」)∈E−r(ω”). . . f‘)rall j≧」1 and a皿ρ=0,...,n−1.5
6
HIGHER DERIVATIVES. hN LINEAR RANKED SPACES
PR・・P. P・t v={Vk}(∈X。。(E)),・nd 1・t理回二Vk・・…IVk.(p times). (1): By the relption ∫(n−1)(・+.h)(・)一∫(カー1)(・)(司=rn(九)(x)+∫(n)(・)伽) a皿dby(†), it su伍cies to show the eXistence of u’∈fo(.F)with the asserted property. A・∫(・)(・)i・v・一・・nti皿・u・at th…igi・, th・⊇・’∈f。(F)・U・h・th・t{∫(・)(・)(咋π】∩ E★(vn))}、く・’一・’.1・・・…=1, it i・・bVi・u・th・t∫(1)(・)(λ」㌧)→b(P一の.Assume n≧2. Let{μ」}be a sequence of positive皿mbers such that朽↑oo a皿d
μ劫→0圃(the eXistence of such{pj・}follows from[4, Lemma 1.41, since the
le㎜a rem垣ns司id in E). Then we see ∫(n)(・)(λ海・」)=f(”)(・)(μ」λ海μ;11( 1)・」)ニー0.(P−ut). (2):We prove the f()rmer part. Assume n≧2. As f(n−1)(α)is vn−1−continuous ・t・th…igi・,.th・・e i・ω∈f。(F)・u・h th・t{f(・一・)(・)(咋 11∩E’f(・・一・))}k K・v一ω. Let u”∈端(F)be as in(1). By(A.1°), choose w’∈尻oo(∬)such that u”十ω一一くwt.Then from
∫( 1)(・+λ」㌧)(・」)=∫(n−1)(・+λ」・ん」)㈲一∫( 1)(・)(・」)+λ;(n−1)∫(n−1)(・)(λ」Xゴ) it囹1㎝s that∫(n−1)(α十λ」九」)(¢」)∈E★(ω’)for.all the suficie皿tly largeゴ,s.1皿case n=1,chogse◎∈先(F)spch that∫(α)∈E★(◎). Then the plece(五ng argument is valid withω=◎. CoRoLLARY 1. Leげ:1)→・F be n‘fmes R−v−(五fferentiable atα∈D, where n≧1a疎f v={Vk}. The皿,91’ven x∈E★(vn−1), t五ere js uエ∈チb(F)such that {∫(n−1)((・+Vk)∩Dつω一∫( 1)(・)ω}、く・r・・ where 1)*=D∩(α十E★(の). Tlle fbno理ing are e{rs. ily velified:PRoPosITIoN 3. Let 1)be R−v−(∼pe皿fbr some v∈foo(E). Let∫:D→F,
9:[α,β)(⊂Rl)→Fand lρ:[α,β)(⊂丑1)→1∼1, whe肥Fjs(π一T1)and丑1
f・th・・pace融n in{5, Ex・・iipl・1]. L・t b∈D, and・1・‘ん∈E be…虫‘h・‘
θ九∈(・D−b)∩E★(のfbr a∬θ∈{0,1].(1)1f bo‘h f and a map∫A;1)→Fare・n舌fmes脇一(晒肥皿‘jable a‘b,‘力en
s・」s‘he励p 8∫+坊血・my re㎡加mb・ぽ・姐dちa・d・then(3∫+㈲(n)(b)=
・∫(・)(b)+tfln)(b).M.HIKIDA
7
(2)iff’is n‘∫mes R−v−(lifferen‘iable・at xO十b.(¢o∈(D一乃)∩世@)), the丑so is ‘h・卿ゐ・(D−b)∩E・ω∋x,→∫(x+6)∈F・t・・x。a・d f,n)(x。)= −f(h)(x。+b); (3) 1f bo‡h g and.9 are R−《h’fferen‘iabJe(」丑毒五e sense of同)a‡‡o∈[α,β),‘hen so js‘he map 91:(盈1:))【α,β)∋‘→9(t)9(老)∈・F andσ1“(¢o)=9’(τo)σ(to)+ 9(to)9’(to). ., (4) 1r∫∫sη‘∫mes】缶u−(lifferen‘∫aぴe a‘6十θ〇九(n≧1,θo∈[0,1)),伍e皿,血 ・ny・fix・d y∈E★(vn−1),¢h・・卿9、・(盈、⊃)[0,1]∋θ→∫(n−1)(6+θ九)ω∈Ff・ R一繊・㎝‘」・田・a‘θ。鋤dg、’ iθ。)=∫ω(b+θ。ん)(九,y).1 PRoPoslTloN 4. Le‘v∈尻oo(E), and Iet m..≧1be an integer. Suppose‘ha‘ L:B(vm)(⊂Em)→F蜘冊一con‘」皿uous and皿㎡碗皿ear, where F is(π一丁1). Then, f()rany i皿teger n≧0, we have . . ・ ・:“ (i) L∫sη‘imes R−um−djfferen‘jable a‘eve」ry a.∈E★(vm);and L(冊)(α)js a con− s‘a・t.高≠堰E,・・Lω(α)=O・if n>m. (2) The mapτ:(E⊃)E”(v)∋九→L〈九>m∈Fjs n tjmes R−v−(fifferentiable a‘ eve1ア九∈E★(句:and‘hen, if m−n=ρ≧0, 〆π)(h)(『1,・∴,Xn) ・1 陸 8P = Σ Z) L(・。(、),_,》,_,x。(」),X,・。(」.、),_,》,...,x。(。)). 1≦‘1<…<輌▲〈…◇ρ≦mσ w五eTe(¢1,...,xn)∈E★(vn).andσfs a permu tation of.{1,_、n};and so e{F)(ん).=0’ifη>m,
2..Taylor,sゆula. In the.fg皿owing Theorems 1−3,,.Lemma 2 and Coro皿ary 2,16t Db・R−v−・p・nf・・s・rP・.v .E・T・・(E)・ndl・t Fb…卿・¢(・−T・)皿d・ati・fy 伍econdition(A.2’)of[5], where F being co皿vex means that the prenelghborhoQds of .the origin of F are convex:When∫:D→F js n times R−v−differentiable at a∈D,we ppt
ax(・)一∫(・+・)一主±∫ω(・)〈・〉・(・・(D−・卿)・
The following is Taylor,s formUla correspondmg t。 the definition of(1 times) R−differential)畢ity:、 THEoR.EM 1. Le‘∫:1)→Fbe n times R−v−(fifferentjable a‘α∈1), whele n≧1 a皿dv={Vk}. SuppOse that F satfs6es(A.1°)and‘ha‘, jn‘五e case n≧2,‘力efolloWing力dds:
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HIGHER DERIVATrVES IN LINEAR RANKED SPACES
(‖) For eachρ=0,...,n−2,‘here丞fOp suc力that Vkρ.⊂(1)一α)∩E★(のand ‘ha‘,」for any fixed九∈Vkp,舌he lnap (Rl⊃)[0,1Dθ一一∫(・)(・+θ九)〈九〉・∈F fs c・ntinu・us・n[0,1]. 令.. 丁五e皿 、 (1) There em’stsω∈チb(F)such that. λ7( 1)se・一・(λ・九・)丁・(P−・)
f()revery{んゴ}∈9(v)and evely{λ」}∈A. . (2) There eXistsω*∈巧〕(F)such that if‘he restric tio40f∫(抱)(α)to E★({)n)is symmetric ft)r∂∈Fo(E)Wl’εh∂一〈V,‘hen λ;・・”・een(λ」んゴ)丁゜(P二∋ f・・’ Ev・・y{h元}∈9(・)吐f・h・i・・eve・t・ally in E’(∂)and・町{λ」}∈A. Thus jf we ch・・se・di∈fo(F)such that・w+ω*一くdi,‘hjs励麗b・εh pr・perties()fω a皿(1ω゜. PRooF。 When n=1, the theorem is obvious. Assume n≧2below. (1):Let u∈fo(F), u’∈乃(F)andω”∈fo(F)be as in(†), as in Lemma 1(1) and as in Lemma 1(2)respectively. Chooseω∈foo(F)sllch that u十u’十ω”〈w. Putωニ{Wk}, a皿d let松be such that Wt⊂E★(ω).Let{ん」}∈9(のand{λ元}∈Abe given. Fix k≧max{ko,_,kn_2,松}, and
choose m>kso large that 4Wm⊂Wk. Then, by the choice Ofω, we can丘ndアin
such a way that λフ<1, λ」んフ∈レ;iZ, ∫(ρ)(α十θλJhj)〈ん」〉ρ∈E★(ω) (pニ0,...,n−1), ∫(・)(・)(θλ」ん元,〈ん」〉・」1)∈Wm−Wm, λ;1・。(θλ」ん」)〈ん」>n’1∈wバWm, w}leneverゴ≧ゴ’andθ∈[0,1]. Fixゴ≧ア, and define g:[0,1](⊂R1)→FI)y 9(θ) 一§ご(・一・)・λヲ∫…(・+・λ…)〈・・〉・+(。…、),(・一・)・一・λ7−・∫・・一・・(・)〈・・〉・一・・.M. HIKIDA
Then g is continuous on[0,1]by(#), and, by Proposition 3, g is R−di丑erentiable ateveryθ∈[0,1)and
・’(・)一(嵩2λ7−・[f・n−1・(・+・λ・㌧)〈・・〉パー∫・−1・(・)〈・・>r −(嵩2λ7−・[・・(脳・)〈・・〉・−1+∫…(・)(・λ・ん・・〈・・〉・−1)]・ Obv輌ously g([0, ID⊂E*(w)and g舎([0, i))⊂Et(ω);and for allθ∈[0,1)・’(・)・(高2λ7−・(W・・−W・f−Wm一陶・・7−・2(Wm一嚇
Hence, by[5, Theorem 3.1]we obtain9(1)−9(0)∈λ7−12Wm−Wm(P一ω)⊂λ7−14(Wバ閲⊂λ7−1鰍一Wk),
th・t i・,λ;( 1)Sen.、(λ」ん」)∈Wk−W、.・Thi・end・th・p…f・f(1)。 Remark thaもif∫(n)(α)ニOon]ぽ(ur)f〈)r vl∈フ㌔(E)with vl 一くv, then in the above proof, assumingんゴ∈B(vl)fbr allゴ≧プ, we have ・“(・)一(蒜2瓢・・…)〈・・>n−1∈・7(Wlm−Wm)・ and so it fbllows from the same reason as in the al)ove proof thatλ;π挽炉1(λ」ん」)∈ Wk−W[k. Consequently we see that if the restriction of∫(π)(α)to E★(vf)輌s identically O,thenλ;n貌π_1(λ」九」)→0(P一ω)f()正every{㌧}∈9(∋which is eventually in E★“1) and every{λゴ}∈A。 (2): By Propositions 3 and 4,貌n is n ti▲皿es R−v−differentiab}e at O∈(D一α)∩ E★(の;and obviously, for each g=0,_,n−2a皿d f()r any丘xed h∈Vk,, the map (Rl⊃)[0,1]∋θ→貌隻『)(θ九)〈九>q∈Fis continuous on[0,1], where kq is.as in(‖). Theref()re, by the remark give皿at the end of the proof of(1), there eXists w*∈JFIo(F) such that if電π)(o)=oon E★(吋)f〈)r v1∈チb(E)with vlくv, then・7[een(・…)一嘉蹄・(・)〈・・hl>9]丁・嗣
f()revery{hj}∈Q(∋which is eventual}y in E★(vl)and every{λj}∈A. Now, using Propositions 3 and 4(2), we have 酬@・,……)一∫(・’(・)(……,・・)一;Σ∫(・’(・)(・・・……・・・…) f()rq=0,1,_,n, where(xl,_,xq)∈登㊤q)andσis a permutaもion of{1,_,q}. Trivially SeS())(0)=0;and靭)(0)=Oon E★(v);and, f()r g=2,...,n, SeSg)(0)〈x>q=09
‘10