TRV Matheπ匿tics 14−1 〔1978)
ON STAB工LIT工ES OF EXPAND工NG ENDOMORPH工SMS OF
COMPACT MAN工FOLDSMa8ato8hi OKA
(Rece ived May 19, 1978)1㎜lm㎝.1綱鞠e㎡㎝叩hisrns。n finite dirnensiona1 cormected
dO c㎝Plete C Rienannian taanifolds without boundary鳩re investigated by M. S㎞b 【7]. He proved that expand ing end㎝orphisms on compact comected C°°Rie− mannian manifolds without boumdary are structurally stable. On the other㎞d,R. Bowen stated加【1]t㎏t㎞㎝⑩叩hi珊s。f卿ct metric s照ces with
e閃pans iveness and pseudo orbit trac ing Property (stochastic stability, cf. 【5】 ) are topologically stable ill tlle strong sellse, In this mte, by us ing pseudo orbit tracing property for endomorphisrns, we prove that e即㎝ding end㎝orphisms on c(rmpact comectedσ゜°Riamian manifolds without boundary are topologically stable ill the strong sense and also structurally stable in the strong sense. 1. DEFINITIONS AND rOrOLOGICAL STABILITY. Let X be a metric space with metric function d. ・・F・N・T・㎝・… equ・nc・e・{xi}二。 is said・・be aδ一P・印㊤6・bi・f。・ a continuσus map f“ X >X if dげ(Xi)・Xi,1)≦δ f・r i−O・1・2・…・ A.point y e l X ε一tlraces ¢ ff . − 4r〆ω・ヅ≦・ f・・“t.ヱ.2.…. Where fO(x)一。f・r孤y。,X. DEFINITION 2. there exists ε0 > O eger n when x X y. Aconti皿10us map了ごX >X is positively expansive if su・h t』t 4σ㌔九戸ωノ≧・。 f・r・㎝・n・・−n・g・ti・・int一 εO is called an expans ive constant ofア・ DEFINITION 3. Acontinuous map了ごX >X is said to have the pseudo orbit tracing property if for any e > O there exists δ > O such that fbr any 2930 M−,.eKA δ一pseudb oゴbit of f{!, there ercists y∈x砲ichε三traces…三. ・。th。 fb1・砿㎎,・i。 a c卿。t・mdt。元鋼ce, and 10txノ.i。。。pace・f all continuous maps of X wig..the metriC 4。rf.・ノー弧{d・rfr・).・rx〃sx・・}. fs・・i・°・(・)・ DEFINITION 4. A cont迦ous皿ap.王.ごX 琴is said to be topologically stable in the stro㎎ sense if fbr any ε > 0, there exists δ > O with・the f…。砲騨・P・・ty・f・・aPy・9・E°(・)・wi・h d。rf,g」・δ,・he・e・exi・t・
逗゜α)鋤血口・9−f・方画%rW≦・,噸・・X i・th・id㎝・ity卿
of」rぽPROPOSITIOU・1(R. B・XUi[1D. if f・砲〃・函励殉卿・i・¢
磁《.ha8』P8euゐρrbit tvaOfng・.ρ㌘OP傑勾. thenアis topρZogieaZZy 8励Zθin 祐θ8加oησεθη8θ. This proposition is stated・essentially in [1]. We shall gi噸the・ proof. . . ke・・ア・L・t・0・Ob・an・XP・n・iv・・c・n・t・nt・fτ・F。・any・e>δ:we㌶㌫ltε‘8蕊。1°;::e>二1,㌻㌻蕊δ。;.1。芸;£r
N・・;・f・。rf,・)・・,・…n・f・r・・…x・X,{ gt (x,}島訂・δ一P⊇・rb・t 。f f・lh・・efb・e・f・㎝・ヱ<ε〆2・th・t・e・i・t・㎝麺・y‘X・Whi・hε1一ぬces{θt rxJ}二。,i↓・・ .
エ 6r子ω・gt・la〃≦・、・.. i’t…2・…・ Here we define h:X−一>X by hrx)=9・ We show hog=foh as follows;. Frαn the definition of h, fbr any xξX の d (ft (k (9 (・)))・ gt (9 ・a)) )≦・1・m…,・・…・.ω. Also, 4r〆+1r・ω九∼㌔ωノ)≦・ヱ.)o。ヱ.2,…. r・) for a皿y xεX. Fr(ぬ a), r2),we get .ψ晒川・舟願〃月≦・… i−・…2・∵・・
for any、x∈x. Since ε1 < ε0/2, we have hog=了oh.ENDCmORPHISmS OF OOMPACT MANIFOH〕S ・ 31 h is contil皿ous・ Because, if h is not continuous at¢0「∈X, th㎝there
exi・t・a・剛㎝ce{却二、血血㎜・erg・・t・x。・㎞・胸鵠品eS nC・
・・rv・・g・t。輪。L Since x i・c卿・t・鵬㎝ass㎜・th・t{h(・。)}三
c・mverges t・y・X which is differept frα・h (xO) ’貯㎝.P・sitive∈卿ive− ・ess・ばr飾九fn rh rx。〃,≧・。 f…㎝・n㎝一neg・tive血ヰ・g・・m・th・・efb・ethe「e斑sts a psitive i・t寧・0鋤d旭t
drfn(hrx.〃・摺侮。〃・)≧・〆2 」b・孤y・≧・。・ r3」 On the other hand, frt n the definition of h,4♂r殉〃・♂馬〃≦・、・
[[1ierefore we have 6♂伍侮。〃・ Sinee{・v}こ、・・w瓠gesV1≧vO・uch Vhat
診● ■ ■ ■ ・ ● ■ 診診 9●9一33
7ユ?占33
ゆ。浴B
r4)gn’la。昼・ヱ・ nt・ヱ・2・….・ r5)
t・xO・th・re e・i・t・ap・sitive int・g・r vl with 4fみ∼ノ・θ%。〃≦・呈・ fb・any・≧’・ヱ・ Hence we have d(fP’(hrx.〃・戸輪。〃昼・・、<ε〆・・ f・r v≧・、 This contradicts to (3,. Therefbre h is contimlous on X.F’・n th・d・f桓iti。・Qf・h・鳩㎞㎝40伍・1∂≦・2… q・E・D・
2.{㎜㎜1㎜.
In・the f・11cWing,〃is a c・IlrPact c・nnected・C°°Ri卿i飢㎜if・1d砿th−out b(輌・ An endomorphism of〃is a differentiable fU㏄tion丘㎝〃to〃,
紐とif it i・・f♂−class, r≧1,we・a11♂−end・m・rPhi・m.班FIMTI㎝.5.σ2一㎝d㎝・rphi珊了。f〃i・e・綱mg if th眠exi,t.
・。賦孤t・σ・鋤dλ・・su・hd遭tl夕飼−≧σλ”同fb・『孤y・・四孤4卿
Pe・itive intege!・π・}le・e l…1is the RiqmE迦i・n・met・ic・n〃副野is
the.differential of了. ・Z。。(・)・denote・th・・et・f・a・・〆・㏄・・di任・。・。rPhi… f・cu・M・・〃.・卿飢d・6ω砿・・d㎝・te a c…曲・・a・d・an。pen’.楓・nt・h・㎝…−d
radius r respectively with resp㏄t to the Rienannian metric. .恥asS皿・th・t・一{σヱ・σ2・・…ひ。}姐β一{γ1・V2・…・㌃}ar・⑯・。・er− ingS of〃and that there exist systems of coordinate neigh1)orhoods32
M.bKA
{N「Ui・fli)}:…{・7」・》}≠、瓢・倣tt、・.元〃号・』5弓訂・th・
c1°皿es°fσ∂!ゴ・esp・ct’v・1y・F・「the−一・・㎜・th・・ ・he・・ex’・t・a ㎜Pゴ・‘{1・2・…・・}〉{・・2・…・・}su・h蹴卿已㌧rz/fb・i’一・………F・r・声・iv・輌・rε〉・…t確r・・β・ゴ・アノb・the set・f…♂一㎜P
θごVe>fwith t1Xe fOllowing properties, (i〕 σ仰∈.γ醐 句・2・…・8・ (11〕1物…φ;ヱーピ、・f・φ;ヱ‖,<ε・剖.2,…,8,.噸・卜・1,i・the・一・・m・n・he・pace。f…㎞d・d♂一㎜P・、丘㎝φゼrσ∂
to the m−dimensional Euclidean Space 1∼n, m=d鋤, The set of a11 一 れ.β。ゴ。f」・9・n・r・tes th・♂−t・PO1・gy・fずω血・h i・the set・f・・1♂− maps fr㎝.〃 to〃. 1」Emm・1・ 1わrα哨ダf∈DZoθ「Mθ♪ カ72θヱ゜θ exist constants R > ρ3 V > 0αη〈ヱ・W励・加・飢げノwith r。日ρ。。τ・。σヱ.触Z。σY.SU。力微・鋤卿9,〃げノ
an4 x・M.(i)・r4ωノ蹄㎏ω九
〔ii) σi・W・・励・・π㌦傷ノ・ b・・ア↓桓tα一{”1・σ2・…・ひ。}and B−{Vl・γ2・…・γt}ar・・脚・。…− ings of〃・ We assume that.there exists a map Jξ.{1323..◆38} .〉{ヱ323...,t}鋤血tf「Uiノ∈γ調.fO「仁1・2・…・ぎ・恥・th・m・・∼・・㎜・血t there
ex・・t・y・t−f…輌・…ig吻・h・・d・{NCUi’φi)}ご,・{・弓・㌧ノ}ゴ三, su・h 血・聾q臨う・已弓・and ¢ir・8 are con・e・・set・in Rm・ T1・er・頭・t刀ヱ〉・0飢d O>O ・u・h th4t f・・fU・1id・飢m・t・i・dO ・nd the R’臼㎜i紐鵬t「ic d°n”・侃≧ば・≧「ヱ/のd°n BR、ω×BR、(x) f°「 ahy XE”・ 恥・・…㎜・鴫r・,β。ゴ。f)已・、。。(・)・f・・s・tff・…n・・隅・・ε〉・1・・卿・・屡…β・ゴ・f・…t 9、・・th・Jac…一・・iX・f・ゲψゴ,、晒一ヱ・魎・
駆・)−m血{・/・・21・、ω一11…互}.ENIX》痕)RPHISMS OF (X】MPA(πMANIFOLDS 33”
P「σ,−min{P、侑い2rθ九・…y.ω・ .
S血ce買i・c・n・血・。…n鴫r・。・β.ゴ。了‥㎝・・㎜・t油t th・㏄瓠i・tS−lt:膿、1,:tぱ。1㍑1。ご、顯麟’.R, suCh,ha,i,
dr・・yノ・R,…y・Ui…h㎝1毛ω一W1・2♂・,凪2....。・. Tl・ere
tsε2>°
ム二;蒜三1・: ㌫Slll:鮒’・
if・d「x・yノ<盈2・x・y・Ui・ lhe「e㎝i・t・R>O with R・R2 ・u・th・that・f・・any…〃there朕i・t・a neighb・rh・・d Ui・ with Ui PBRr・九‘W・・hav・ ・;1・φ紳⑭一φ・ …) 」 E BS、ω・・≦・≦・・ fb「x・y・BR「・い㏄鋤・eφ〆〃¢ノi・ac・nvex・et・陥f』・EM and defin・f・・…嘘、r・・醐・一・φ・脇・・
θi rv3 9・tJ=Gi 「v+tu)−Gi rvノーtgi rXO)iら 0≦tE_1・Then
l圭θzω.9.胡=1 9i rφ;・i (v+tzo〃ω一σ汐o川 L ≦1・irφ;ヱ(v鋤〃一・、rx。」t酬・2・2ψ1. ・ince’ lw+1・、・x。戸・μ。・・1≦1・〆。戸l l・〆。加1.鴨・・t ・・2中1≦1・i侮。)・1.Therefo・e l熱ぴ.・川・1・、rx。畑1/・。 and・f・rm th・一輌
theoren we have lei 「v・θ・刀一‘6i rv・σ・0川く19i rXO加1/3・ Hence we get 1 Girv+t・ノーσzω一9i lao加1<.l g〆%加1/3. Therefbre,34・ M.PKA
I・迦ノー馬ω1・21・ir・。川/・≧殉小ω
恥㎞wthat g is珂㏄tive on BR(XOノ・ ’
恥w・if ・d (x・eloノ=・R・then・f「c・iマ1ノ・ 、 侃rσω・grx。〃≧d。仰醐侑伝〃・物rg傷。〃, ≧・・2・d。rφi(・」.φμ。〃 ≧4鋼属虚oノ= 4CpR・恥順殉ω。・(x。〃≧・1・R・Sinc・gi・adi任・。・・rPh・−Bli (x。ノ,鳩9・t
・卓b〃蹄r・rx。〃・ Q・・…
We introduce adaptiedk ineltriCs“.、fbr expanding endomorphisms as fbllows: LE岨2(J.ぬth。。【6】). L。t・f・be。σ1.e、pmding。nd・m・xphi・m・f M. Th・n th・r・ ecists.a・Rieme励伽m・tri・1・1唖α・・n8tmt・P・ヱsuch that l励1≧pn回f・・ any・v・盟叫P・・iti・e i・t・g・… Proof. Letσ>0, λ>2 be the const’ants of the definition of了. Ta](eμ>2with|」< λ. Then there exists a pOsitive integeT瓦 such t1鳳t ・rx/・)k≧ヱ.脆d・fi・・ 1。1・。芒1,−mTfPl.1・,・卿 η2=0 砲ere沸.。.脆ca1、凪。te a。 fb11㎝。,. ‖判・.芒1,一酵・。1・’.,・】i 1,−MT”vl・ . m=ヱ η1=0 ・・2{1・12−1・12坤一ぴ・12} ≧・2{1・12叫vl2・r・rv・ノkl・1/2}≧μ21・12. .q・E・D・
L・t伽・01−eXP・nding・・d㎝。叩hi・m・f〃a・・d・w・・take・an・血pt・d m・t・i・ 。fτ. Then fo・.・uffi・i・泣・y馴砿・ε〉・,・・…㎝㎝…f鴫r・.β,ゴ.糎・㎜)㎜SMS OF(㎜cr MANIrOIDS
・ヱーe・p・nd・n9 e・dtmotp・・s・・s・・nd・f・r…r…鴫r・.β.ゴ.f」・th・…・・t・P・suCh 廿温t.1ぜ・1≧pMl v t{for’lany v・現洞.2。...恥d・f桓e aゴ㎞・t垣nλ・n 尾r・.β。ゴ。f)・・f・…ws・, λrθμ卿{P・−1ψ司≧・mll・・I fb・a・y・v・鵬呼2・…}・
Lem・3. L・”わ。。02一郷.W。n、IO。。uphi。m。τM.』。 e,i。カ
ε〉・a・d・6・・螂吻輌卿9・瞳r・.β.ゴ.ρ励⇔・疏・≦δ。
・・B9・・」」 )・(,9ル碓〃 for any x∈〃. oo boof. Let r (x3 y)be the set of all broken O curve frorn x to y, and co let ’「ξ (x・y) be the’set°f all b「°ken C‘㎜e臼㎝、・t°y in Bξ(x随㎝ y∈Bξ (x)・ Since M is coロ腿ct, theTe exists ζ > O::”一’乏s血Ch.こthat dr・・y)−i㎡{〒s』Y・・rζ (x・〃)} f°「 ・ny xε”伽〃ξBζω・Here Y i・th・1・・gth・f Y・ NDw, fbr suffici㎝tly sma11ε>0, the fUnctionλ is bDunded on鵬r・,β.ゴ。輌d・−P・tλ・皿P{・侑ノ…〃lr・.β.ゴ,f)}・
Fr㎝Lenr田11, there exist 1ヨ> 0,,p > O such that ・峰〃P BilR・・ωノ fbr any¢∈〃. Takeδ>O withλδ’<min{R。ζ、岬}. Then for{my r≦δal凪Y・・1,、ル・・(x〃・曲・・…剛・証{〒・Y・・ζ⑭・y)}・・inc・
y・・晶ω九故・ex・・t…Bll(・) ・i血・r・) −y・ 一
λrθノ・〉趾{〒SY・rζrgω・θr・〃} ≧i皿f{9Yξ⊃Y∈r (x, zJ } ≧’λ (9) inf{Y3 Yεr (x3 y) }=λrgJdrx,9ノ.輪・f・…e油・…コω・ Q・・…
3536 s M.◎KA We obtain the fbllowing propositi㎝丘om r㎝a 3.. PROPOSITION・2.乙.t f b。。♂−e・pa・di・g・・伽・rphi・m・f M.』・
。吻。。殉励吻。d.Nrア,。fτ.with.。。.P。。励♂幽Z。gy.a。d。。㈱繊
δ>Osueh that aZZ、 eZenents・了Nげ)卿ρ・sitiveZy eupccnding mcrps with an eupc nding eonstantδ. THEOREM・3.0ヱーeUP⑳nti・g・㎞・・phi・m・・f〃h・・V・輪・ρ・励・嚇物・物?r・p・rty・ .
b。。了.L・t f b・ ・’ Cl一卿di㎎㎝伽・・rphi・・飢dδ・Ob・the c・n・t・nt・f Le㎜・a 3・陥ぽit・λ加tead・fλげ)・F・・ε>0・w・ tak・δ0>O ・u・h
廿担tδo「2λ一ヱ/λ一刀く肛㎞{・・δ/4}・L・t{・・}二・b・aδ・一一・・rb’t・fア・脆醐・一王鴎P
i“0.ヱ.2。... ,t血en f㎜1 L㎝ma 3, P・「B・〆λ一・「xy” p B・。vλ一・げ(x・”・句・ヱ・2・…・・血・アi・adiff・。・・rphi・・n・n・1侮撫飢y品・w・・9・t・
・・〆・.・・r… ・ F;ヱ…。vλ一・rf・(・・・…D・2・2・一ω Sinc・{xi}二。 i・δ。−P・ed・・rbit, B・。Vλ一・げ「Xi−・」」PB・〆λ一・(Xiノ・剖・2・3・…・ 「2」Fr㎝ω3 r2)3
・・。・/λ一ヱげ(・・一・口・;ヱrB・。vλ一・rf…))・ Fr㎝ω, r3) , we get B・♂一・r・i一ヱ…;三…;ユ…。λ/λ一・⑭九 therefore, we put 亡=232333・・. .(3) を=ヱ32333・.・ 3 ・・〆・,・rx… ・S’・・;c…・・;2…。λハ.・卿〃・ 働ヱ.2。.EN[℃M)RPHISMS OF CCMPACT MANIFOLDS 37 ⊃ 〃 ﹂阜 げ ヨ
ρ
λ0%
ヱr 尻τ O oo ●20
一 ヱF
ヱo 一〇 = .Z i=OJ 2323... 3 then by (O・「2ノ・ w・・ha・・Ai ・Ai。ヱi−・,ヱ.2J…・Since・M・i・c・mPact, ◎O oo £。ゲφ’脆㎞゜w that any e’ement°f£。 A・ε一t・ace・{x・}二・・ Q.E.D. Fr㎝Propositi(m 2 and Theor㎝3, we get the following propOsition by Proposition 1. . PR・POS・T・ON 4. ci−eUP・・nding embm。ilphi,ms S勧力Zθ in the st?ong sensθ. of M al,θ topo ZOθioaZZy DEF・N・T・㎝6・A・2−m・p・f・ M−>M・i…tru・tura・・y・醐・m・h。,t。㎝9’・㎝・eif fb・飢yε〉・・th・r・exi・t・…ighbO・h・・dルげノ・f輌・Zt・P・1・gy
such that fbr any g∈Nrf) there exists a homeomorphism h:M−一一…羽such that h°θ=τgh ・nd do「h・IMノ<ε・ THEOREM 5・ 0ヱーe epandine endomOilphisms of Mα㌘θstt・uottuaZly 8鋤Zθ in thθ st?ong SθnSe. b・・f’Le・fbe a・1−e卿di・g・nd・㎜・phi・m・f〃.取西。P。。i・i。n・2, the「e existδ〉°・・d…ighb・rh・・d・N、・rf] ・u・h・ha・any・9…、・rf/i・a・P・・i− tively・・rP・nding・m・p・with・n・xpanding・・n・t・nt 6. S血ceτi・t。P・1・gically stable in the st「・・g・㎝se・f…〉…here・・xi・t・a・・ig地・血・記・,げJ such t}rat f・・9・百2 rρth・re・・xi・t・a・c・nt麺uσu・m・p h・ −e・M・・u・h・that h°9=f°h ・nd dO「h・IM)≦・/2・F・r・uffi・i・ntly㎝・11ε>0,㈹・;a・・…迦・ that h is a onto map and furthennore we assulne ε く δ. We P”t N「ρ一”ヱ「f)∩η2 rf)・th・n th・ab・v・・h f・・σ・mCf)i・ah㎝・・− morphism of〃. Because, if h rx)=hry/and x S y. then fbr some ncm−nega− tiv・i・t・g・・mw・ha・・drgMr・), gM (y〃≧δ. F・㎝d伽θmω.σMrx〃≦e/2、 4伽9ηr〃ノ.♂r〃〃≦・/2and畑一了・h. w。 h。v。 a c。nt。、di。ti。n、uとh t}rat ε<δ≦4r♂ω。♂r翌〃≦・. Theref…hi・a知・・(m・・rphi・m・f・M. Q.E.D.38