光滑闭流形上的Lefschetz不动点定理

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南开大学
硕士学位论文
光滑闭流形上的Lefschetz不动点定理
姓名:***
申请学位级别:硕士
专业:基础数学
指导教师:***
2012-05
中文摘要
中文摘要
这是一篇读书笔记,参照文献【l】,用热方程的方法证明光滑流形上的Lefsehetz不动点定理,并给出计算Lefschetz数的公式。

文章先介绍基本概念,包括傅立叶变换,拟微分算子与象征,椭圆链复形;利用Hodge分解定理将Lefschetz数与椭圆算子的零特征值特征子空间相联系,再联系到固定椭圆算子的所有特征子空间,从而转化为热方程的解的积分核的迹,此热方程有椭圆算子,解由椭圆算子决定,最后利用椭圆算子的象征变形,再积分,得到结果。

关键词:拟微分算子,象征,椭圆算子,热方程,Lefschetz不动点定理
Abstract
Abstract
Thispassageisareadingnoteofthebook【1】bythemethodofheat
equmion,giveaproofoftheclassicalLefschetzFixedPointTheorem,andgivetheLefschetzFixedPoint
Transform,Pseudo.Formula.Firstweintroducethebasic
concepts,includingFourier
DifferentialOperatorandsymbol,ellipticcomplex;associateLefschetznumbertothezeroeigenvalueeigenspaceofellipticoperatorsbyHedgeDecompositionThereom,
moreover,toalltheeigenspaceofellipticoperators,thenchangeintothetraceofinte-gralkernelofsolutionoftheheatequmion,whicharedeterminedbyellipticoperatorsrespectively;atlast,usethesymboloftheellipticoperator,whichwedifferentiateandcombine,thenmutliplyconvergencefactorandintegralthemtogettheresuR.KeyWords:Pseudo-DifferentialOperators,symbol,ellipticoperator,heatequao
Theorem
tion,LefschetzFixedPoint

Chapter1Introduction
Chapter1Introduction
LetMbeacompacttopologyspace,assumeMhomeomorphismfinitesimplecom·plexes,amapf:M_÷Minducesalinearmapofthehomologygroup^:绋(肘,Q)--t,炜(肘,Q),thenLefschetznumberisdefinedby
L(,)=∑(一1)pTr(y,onHp(M,Q))

TheLefschetzfixedpointtheoremis:ifL(f)≠0,thenfhasfixedpoint.In【7】,thereisaproofbytopologymethod.
Inthispaper'weassumeMtobeasmoothclosedmanifold,meansasmoothcompactmanifoldwithoutboundary,andf:M---}Mbeasmoothmap.广definesamaponthe
cohomologyofMandtheLefschetznumberoffisdefined
by:L(,)=∑,(-])PTr(f"onnp(肘;c))
Wegetthemainresult
Theorem1.1.(LefichetzFixedPointTheorem)
矿己(力≠O,thenfhasfocedpoint.i.ethereexistx∈m,suchthatf(x)=工
Theorem1.2.(ClassicalLefschetzFixedPointFormula)
Letf:M—+Mbesmoothwithisolatednon-degeneratefixedpoints.Then:
£(,)=E(-1)pTr(f。

onHp∽;c))=Esigndet(1--df)(xi)
pf
Wecanconsideramorcgeneralcase,anypartialell
ipticcomplex.Weget:
Lemma1.3.Let僻E)beanpartialdifferentialellipticcomplexoverMandletf:M_MbesmoothoCinducethemap广:r(e)_÷r(广陋)),where广陋)=工勘b)×%伍)bethepull-backbundle.That西?仃∈r(E),(厂a)Cx)=仃(厂(工))Weassumegivenlinearmaps靠:局,,0)--+目加∞wedefineF=妒io广:r(e)--+r(E),suchthat毋F=F毋aboutthevectorbundle岛.Thenfand咖induceamaponH‘(只y),wedefine
L(f)p=∑(一1)‘rr(F+onH‘∽y))
Thenwecompute
L(f)p=∑(一1)‘Tr(F+P叫令)
whereAi=芹毋+毋一l肇listheassociatedLaplacian.
WeusetheheatequationmethodtocomputetheLefschetznumber.
1.Wechangethenumbertobethetraceof
operatorf*e一岱
2.Computethetraceofoperatorbythetraceofthekerneloftheoperator
3.UsetheinitialoperatorA'ssymbol,togettheoperator(A一九)-1bythemethodofpseodo-differentialoperators,thenget
P叫△-一壶上e-tZ(△一Z)-1dZ
Weusethe
followingtheorem:
Lemma1.4.LetPbeanellipticpartialdifferentialoperatoroforderd>0w办耙办isself-adjointandwhichhasapositivedefinitele口dingsymbolfor专≠O.Letf:M_Mbeasmoothnon-degeneratemapandlet驴:E厂仅)-÷晟beasmoothvectorbundlehomomorphism.WedenoteF。

=咖of*:r(e)--+r(广(E))—÷r(E).IfK捃thekerneloye舯thenTr(f*e郇)=厶Tr(F+K)(f,工,x)dvol(x).
(a)lffhasnofvcedpoints,ITr(广e-tP)l≤Gt万asyo,.anynyo,.0<t<l
(b)lfthefixedpointsetoffconsistsofsubmanifoldMlofdimensionmi.wewillconstructscalarinvariantan∽whichdependfunctionallyupona加itenumberofjetsofthesymbolandoff.Theanx)aredefinedoverMand
Tr(F*e-tp)一军∑f警厶酬drol(柚f-÷o+n=0f.,』W
dvoli(x)denotestheRimannianmeasureonthesubmanifold.
’1.hen
L(,)=∑(一I)PTr(F*e-tAp)一∑∑f竿A一(x)dvoli(x)
Pin=O
whereAn(x)=∑p(一1),a^@,Ap).Sincethelefthanddoesnotdependontheparametert.Wejustconsiderthetermwhere九一mf=0.
WeusedeRhamisomorphism,thatisHP(M,C)竺HP(d,人(肘)),tocomputeL(f)on
manifoldbythedeRhamcomplex,asaspecialcaseofelliptic
complex,andusetheinstinctcharacteroftheoperatord,differentialformA(M)tocompletetheproof.

Chapter2SchwartzClass,FourierTransform,SobolevSpaces
Chapter2SchwartzClass,FourierTransform,Sobolev
Spaces
Letx=(XI,…,Xm)∈Rm.Ifx,Y∈Rm,wedefinex·y=xl-Yi+..J.m·YmIXI=@·x)主
astheEuclideaninnerproductandnorm.Leta=(Ofl,…,‰)beamultiindex.Theajarenon·negativeintegers.Wedefine:l口l=Ofl+…+‰,a!=al!…‰!,--X?1...磅
Finally,wedefine:
鳄=(岳)∞…(毛)‰and磷=(一f)lal砰asaconvenientnotationformultiplepartialdifferentiation.
Definition2。

1.Schwartzclassy
夕={,:Rm_C,smoothcomplexvaluedfunctionsJbralia,flthereareconstants%.suchthatlxaD堂xfI≤G,口)
Thisis
oftheform:
equivalenttoassumethereexistestimates
fI≤G,口(1+Ixl)叫forall(行,卢)
Thefunctionsinyhavealltlleirderivativesdecreasingfasterthantheinverseofany
polynomialwhenIXIisbigenough.
Weletdx,dy,etcdenoteLebesguemeasureonRmwithanadditionalnormalizingfactor
of(2,t)一’n/2
Wedefineconvolutionproduct
(,+g)x)=ffO-y)g(y)dy=,,(y)g@-y)dy
Definition2.2.Fouriertransform
Wedefinef∈5p_÷,妙,(毒)=fe-ix.喜f(x)dx
Lemma2.3.TheFouriertransformisahomeomorphism夕j5psuchthat:
扛砂,(x)=feh’{,(考)d考=,∥“—),)’{,◇)d矽毒∥一Dlf,?妇,inversionformula);
例,嗜=(死)删,木雪=(死)(TheFouriertransforminterchangesthetwomulti-
plication)
俐玩FouriertransformextendstOaunitarymapofL2(Rm)一L2(Rm),suchthat(f,g)=(,,季).(Plancherelthoerem)
(d)Daf(x)=,P“《回({)=,P“·毒{口,(考)d毒
‘differentiationchangestOmultiplicationofpolynomial’
毒a,(考)=,辱aP一及·{f(x)dx=fe一扛‘考碟,@)出
‘thenorraoforderadifferentiationchangestOthenormofmultiplicate毒a’ProofiSee【1】P.5
Definition2.4.SobolevspaceHs(Rm)Oomeasurederivatives砂驴normI·l∥
l/s∈Randf∈只wedefine?
腓=/(1+盱)5I,(考)12d,i
TheSobolevspace风(Rm)括thecompletionofdPwi砌respecttOthenorml‘IJ
Lemma2.5.霹extendstOdefineacontinuousmap碟:凰_÷皿一…
门口IorderL2derivativeslost)
跏够I毒f1…考争I≤(1+髻}+…繇)口-t..‰
means:l考口12(1+I引2)s-i口I≤(1+I考12)5
impliesthat:lO譬f12_…=们+盱)s-lall考口,(考)12d,i≤i/I.2forfE夕
WegetID譬^一磷g小Il…sI厶一Sml2,,forany厶,gm∈S
Soiff∈%,thereexists厶∈墨suchthatI厶一厂Ij.+0,asn--'t+∞
Wedefine碟,bythelimitofDxa.fnunderthenormofl·ls.Acoordingthelastinequa-tion,thelimitexistin%-I=1,anddoesn'tdependonthechoiceof{fn}I-IWecanalsousethesupnoFmtomeasurederivatives.Ifkisannegativeinteger,wedefine:
I,I*^=嚣I逸一碟,Iforf∈S
BythefactthatuniformlimitofcontinuousfunctionsiScontinuous,thecompletionof夕withrespectthisnormisasubsetofC七(渺)【thecontinuousfunctionsonIRmwithcontinuouspartialderivativesuptoorderk).
Lemma2.6.kanon-negativeintegerands>七+筹
id:l-Is(Rm)q口(R小)wUhtheestimateIfl。

,史≤Clfls.(SobelevLemma).
碟,=/P硝考a艇)d{
=/∥(1+艄。

/2肥)·(1+艄一,/2毒ad言<Ifl2f(1+艄一‘考2口

forlaI≤Ji;:,2J一21aI≥知一2k≥m,thelasttermisintegrable.Bythefactthatuniformlimitofcontinuousfunctionsiscontinuous,fis萨.口
Lemma2.7.es>t
倒id:飓q凰continous
例eKisafixedcompactset,let{厶)∈SbeasequenceoffunctionswithsupportinK,andsupposeI厶JJ≤C(constantff'o,.all阳.Then,thereexistsasubsequence厶whichconvergesin日.(Rellichlemma)
Proel(a)fromthatifs>r,(1+I引2)5≥(1+I引2)5
(b)forI,皆=fl/12(1+I{12)’d毒,weestimate.J毫(考)
chooseg∈C芋0(Rm)whichisidentically1onaneighborhoodofK.Then柝=.fnSObylemma1.3(b)fn=营宰五.Welet西=毫,then西值木五)SOthat
西五({)=-厂西营(考一<)·五(g)d‘
byCauthy-Schwarzinequalityandthefactg∈C孑cS,so蜃∈S
IajA(考)tsI厶I,·{.厂I西雪(考一‘)12(1+I善12)一5d;)1/2SC.|Il(考)
whichhissomecontinuousfunctionof考.AsimilarestimateholdsforIJcl({)I.Thisim-pliesthat{A}formsauniformlyboundedequi—continuousfamilyoncompact考subset-s.BytheArzela-Ascolitheorem,for…≤1,thereexistsubsequenceof五,denotedby]1.nconvergesuniformlyon…≤I;for…≤2,thereexistsubsequenceofy,Jbdenotedbyf2,矗convergesuniformlyon…≤2;bydeduction,foranyl(forsimple,weassumeit‘Sapositiveinteger),forl{f≤/,thereexistsubsequenceof/,一1’,l,denotedbyZ,一convergesuniformlyon…S/,wechoosethediagonalsequence五.,
forany,.>o’I毒I冬r'五,iconvergesuniformlyonI喜I≤,'
l五,l-A,七仔=fI五,i一五,k12(1+l引2)‘d考
Wedecomposetheintegralintotwoparts,考≥rand考Sr.
on考≥r,weestimate(1+l考12)’≤(1+,2)’一5(1+I髻12)sSOthat:
^喜I≥,.IZ,』一五,七12(1+I考12)‘d考≤(1+,2)卜5ft]j一五12(1+lEl2)5d考
≤2C(1+,2)卜5
Ife>0isgiven,wechooserSOthat2C(1+r2)t—S<£
On喜≤厂,fortheuniformconvergence,wechoosel,klargeenoughtoboundtheintegralbythegivene.Thiscompletetheproof.口

Lemma2.8.TheL2pairingwhichmapsoqexy_cextendstonmap可HsxH—s_CwhichisaperfectpairingandwhichidentifiesHswithH:。

Thatis:
心砂I(,,g)I≤Ifl,IgI—sforf,g∈夕
(b)givenf∈夕thereexistg∈夕册(f,g)=Ifl5Igl—jandwecandefine
fls=g∈夕su,pg≠。

百I(fi,g)l
e门oof.(a)justusethefact(,,g)=(,,掌)andtheCauthy-Schwartzinequality.
(b)takegtobedefinedby:雪=夕(1+l引2)5∈Sandg=蚕(一曲
仃,g)=驴,雪)=I邝andIg|乙=I,曙口
Remark:IdentityHswithH=swillmakeitconvenienttocomputethenormof%,bytheinnerproductofL2

Chapter3Pseudo-DifferentialOperatorsonRm
Chapter3Pseudo--DifferentialOperatorsonRm
Definition3.1.p(x,考)话asymboloforderdandwewriteP∈铲矿
倒p(工,善)issmoothinO,考)∈Rm×Rmwithcompactxsupport.
(b)forall(口,卢)therealeconstantsca,口suchthat
睽噬pO,毒)I≤巳,卢(1+吲)d-I#1
ForsuchasymbolP,wedefinetheassociateoperatorP(x,D)by:
p(x,D)(,)(x)=,扩’{p0,考),(考)d考=,一似-y)‘{p0,)f(y)dyd{
9_50
asalinearoperatormapping
Ifp∈一foralld,thenwesaythatP∈S一。

OurfirsttaskistoextendtheactionofPfromy协Hs.
Lemma3.2.LetP∈sd,thenlⅣI暑一d≤Clflsforallf∈S尸extendstoacontinuou¥mapP:Hs--'tHs—dforons.
口WeintroduceanequivalencerelationontheclassofsymbolsbydefiningP—qifp—q∈S-'.Wenotethatifp∈S-**,thenP:飓_埔forallSandtbyLemma3.1.Sotcanbechosenverybig.ConsequentlybyLemma2.6(SobolevLemma),P:皿寸GforallS,SOthatPisinfinitelysmoothinginthiscase.Thuswemodoutbyinfinitelysmoothingoperators.
GivensymbolsPj∈擎j,wheredj_一∞,wewrite
P一矸Pj
ifforeverydthereisanintegerk(d)suchthatk≥k(d)impliesthatP一∑{∈∥.Weemphasizethatthissumdoesnotinfactneedtoconverge.TherelationP—Y'.pjsimplymeansthatthedifferencebetweenPandthepartialsumsofthePjisassmoothingaswelike.
LetUbeaopensubsetofRmwithcompactclosure.Letp(x,{)∈sdhaveXsupportinU.WerestrictthedomainoftheoperatorPon曰(u)SOP:G(u)-÷G(u).Let甲d(u)denotethespaceofallsuchoperators.Ford≤t,then甲d(u)≤哪(u).(1ikethe

Chapter3Pseudo-DifferentialOperators011R州
㈢董刁
P(三)=/∥。

一力·喜(曼三Pl,lP2,j
:Pk,l^
:j矗一㈦P1.1
恐.,:
ek,f
乱:
.彳1
where昂,jf(x)=fe‘o—y)‘善砌,j(x,喜)厂(),)d∥{
Ifthenumberofcolumnsofmatrixp=thenumberofrowsofmatrixq,wedefineP·qbymatrixproduct,andthecorrespondingoperator尸·Qbycomposition.WealsodefineP·
tobethematrixadjoint,andP·tobetheoperatoradjointsothat(Peg)2(eP·g),wherefandgarevectorvaluedandofcompactsupport.
AssumeP:/-/,—}H.LetIPI蹦denotetheoperatornormsolP,I,≤I尸I蹦I,Ifforany
i∈SLemma3.3.LetK0,Y)beasmoothkernelwithcompactx,ysupportinU.LetP=P(K)
6Ptheoperatordefined砂K.Ifkisanon-negativeintegecthenthereexutj(k),suchthatIKI一,七SC(k)IPI一.『(1|I),一.,(七)
Proof.Firstsupposek=O,choose妒∈c芋(R一),,妒(石)dx=1.Forfixedpoints(xo,Yo)∈
U.we
define:
8、l

Chapter3Pseudo·DifferentialOperatorsonRm
厶x)=/,/m妒(n扛一询))andga(),)=nr'妒Cn(y—yo))
Ko的,yo)=lim一一+。

fy,,(x)tC(x,),)g^(y)dydx=lima一+。

(^,尸g一)
Bylemma2.8.
I(厶,Pg月)I≤I厶l一_『I尸g刀Ij≤I厶I—jlel—J,.,I踟I一_『
Since
吲一.,=/(1+盱)一JlA(考)12d善
五(考)=/e-iX.考n州妒(no—xo))ax
Usingcoordinatechangen(x—xo)=Uwegetj乞(考)≤1.Similarly扁(考)≤1,sowecarlchoosejlargeenoughtomakeI厶I一.fandIgaI一.,bounded.
Iflal≤k,恻≤k,,then:~O僻KCx,),)=lim万_+。

/厶o){p譬彬K@,y))踟(y)ayax
=lima-+。

/(z垮厶o))x伍,y)(D9踟(y))ayax
=lira一.+。

(碟^,肋g踟)
Bylemma2.8.
(碟厶,叫踟)=I霹厶l—jlel一^jlD卢yg—I一.,
SinceI碟厶I一.『5clfl—j+k,sowecallchoosejlargeenoughtogettheresult.口

Chapter4EllipticityandPseudo-DifferentialOperatorsonmanifold
Chapter4EllipticityandPseudo--DifferentialOperators011
manifold
Definition4.1.LetP∈sd(U)beasquarematrixandletUlbeaYIopensetwithU1cU.WesaythatpiseH勿twonUIifthereexistq∈S—dsuchthatPq—l}讯铲.andqp一
1/inS**over沈(Wesaythat,.∈S一“over沈,meanser∈S一”fo,.every妒∈c孑(ur2沙
WesayPseudo—differentialoperatorPiselliptic。

ifitsleadingsymboliseflipt缸.
Lemma4.2.LetP∈甲d(u)bee却ffcoverUI,then:
倒ThereexistsQ∈甲-d(u)suchthatPQ-I—andQp-I一00verUl(i.e.妒(PQ-I)
and妒(QP一,)areinfinitelysmoothingfo厂any妒∈c孑(%沙
0)Pishypo·emptjcoverUl。

i.e.。

iff∈HsandifefissmoothoverUI。

thenfissmooth
overUl.
纠ThereexistaconstantCsuchthatI,Id≤c(Iflo+IⅣIo)力,.,∈c芋(【,1)(whichim-
pliesthegraphnormisanequivalent疗ormforHd)

WenOWconsidertheeffectofchangesofcoordinateonourclassofpseudo。

differential
h:U_0beadiffeomorphism.WedefineJIl弗:c啊(D)_r(u),byoperators.Let
h·fi[x)=fi(h(x)).IfPisalinearoperatoroncoo(v),wedefineI}l。

Pactingon(●(uby(|}l。

P)f=(h一1)’P(h‘,).Thefundamentallemmaweshallneedisthefollowing:
Lemma4.3.Leth:U_÷0beadiffeomorphism.Then7
(a)Ife∈、壬’d(u),thenh,P∈、壬’d(D).LetP=o(e)anddefineh(x)=工l,anddh(x)’毒l=考.LetPl(Xl,毒1)=p(x,毒),theno(h。

尸)一Pl∈一一1.
(b)LetU1beanopensubsetwithUl∈U.ThereexistaconstantCsuchthatIh奉fld≤
Clfldforallf∈c孑(^(u1)).(thesobolevspacesareinvarian0
口Weintroducethequotientspaces一/一一1anddefinetheleadingsymbol吮(P)to
benaturalquotientelementofo(P)
Ifwedefine伍,{)ascoordinatesforT+(胪)byrepresentingacotangentvectorata
lO
manifold
Chapter4EllipticityandPseudo-DifferentialOperatorson
pointxintheformE刍妣,theabovelemmaimpliesaL(P)isinvariantlydefinedon丁’(秽).Means,ifyouchangethecoordinate,theleadingsymboldoesn’tchange,althoughthesymbolofcoursemaychange.
Definition4.4.Pseudo-DifferentialOperatorsOnmanifold
LetMbeasmoothcompactRiemannianmanifoldwithoutboundary.Let,竹bethedi-menMonofMandletdvolorsometimessimplydxdenoteRiemannianmeasureonM.Letr∽)如thespaceofsmoothfunctionsonMandletP:C**(M)o尸似)bealinearop-eratorWesaythatPisapseudo-differentialoperatoroforderdandwriteP∈%(M)?ifeveryopenchartUonMandforevery妒,y∈c-(v),thelocalizedoperator妒尸lf,∈%(u)
That括fo,thechart(U,脚,thehomeomorphismh:UoD,where0isopensubsetofRmwithcompactclosure.(h-1)’妒尸帅‘∈Td(D).
Remark:ByLemma4.3,if(V,g)isanotherchartsuchthatUt'lvisnotempty,theleadingsymbolonh(VNv)andg(UNV)isinvariant,SOthedefinitiondoesn’tdependonthechoiceofchart.
Definition4.5.Pseudo-DifferentialOperatorsonvectorbundle
Let(E,M,砸,口)and(F,M,和,∥)betwosmoothvectorbundleoverM,.LaY(E),F(F)bethesmoothsectionrespectively.Thenwedefinepseudo-differentialoperatorsonvec-totbundleasthat:P:r(E)—◆r(F),suchthatVx∈M,thereexistaneighborhoodUofPinM,andhomeomorphismhe:石一1(£,)_U×ck,hF:万一1(U)_U×d,
hFlyPeh云1∈Td(U)do,.V9,lf,∈c'T0((,).
WehavediscussedthattheleadingsymbolofP,oL(P),isinvariantunderthechangeofcoordinatechartonM.Nowwediscussifwechangethelocaltrivialization.Wecon-siderthesituationthatE=F.IfunV=O,andhomeomorphismhu:万-1(U)_U×口,hv:1[-1(y)_÷V×萨,g∈Fo(unv,e)isalocalsectiononuf)v,hu(x-1(x))=扛,U1)-.-'1矿),hv(Tt-10))=0,',1’...,伊),SOtherewillbeatransitionmatrixgv,u:M_OL(k,c),suchthat
hv"hvI(x,v)=(x,gv,vu)(:j:)=gV,U(:
ll
^uyP9,z云1(:)=/Pf伍一"《p【,。

,考,(二:兰;)由珂毒
^yP妒^歹1(:)=.厂Pf伍一力曹朋。

,考,(:暑;)由履{SOfromJ}l£,妒9=hu-^孑1hvu/e,p,weget
Pu(x,考)=砘-。

1…x,考)gKc,
,SOifpviselliptic,thenSOdoesPu,SOellipticoperatorisinvariantonthebundle.
12
Chapter5HeatEquation,EllipticComplex,HodgeDecomposition
Chapter5HeatEquation,EllipticComplex,Hodge
Decomposition
LetEbeasmoothvectorbundleoverM,denoter饵)tobevectorspaceofthesmoothsectionofE.ChooseafixedHermitianinnerproductonthefibresofE.WeusethisinnerproductandRiemannianmetriconMtOdefineL2(E)
Lemma5.1.LetP:r(E)-÷r(E)beanellipticself-adjointu/DOoforderd>0.(a)Wecanfindacompleteorthonormalbasis{籼)暑forL2(E)ofeigenvectorsofP尸籼=A籼
(b)TheeigenvaluesofPisatmostcountable.Theeigenvectorsphinarcsmoothandlimn.÷。

l厶I=∞.
(c)IfweordertheeigenvalueslAmI≤l赴I≤…thenthereexistaconstantC>0and6>0suchthatI厶I≥Cn6ifn>nolarge

Lemma5.2.Let尸:r(e)_r(e)beanellipticself-adjointLPDOoforderd>0withpositivedefiniteleadingsymb01.Thenspec(P)iscontainedin【一C,∞)forsomeconstantC.

WeusetheRiemannintegralwithvaluesintheBanach
spaceEND(L2(E))todefine:
e-tP=一芴1厶ff-0,~,P一九)一1以
whereyisthepathabout【-C,∞)ofthestraightlinesRe(A+c+1)=士Im(A)withthecounterclockwiseorientation.WeletHbetheclosedregionofCconsistingofytogetherwiththatcomponentofC-ywhichdoesnotcontain【-C,∞)
WefixsuchaPhenceforth.Theheat
equationisthepartialdifferentialequation:
(岳+P)g(x,f)=o,fort≥0withg(x,o)=g(工)
Wedefine:
K(t,X,y)=Ee-tZ"籼∽圆“(),):马一晟
WeregardK(t,x,y)asall
endomorphismfromthefibreoreoverytOthefibreofEoverx.and
P-,P删=厶脚,剐)酬加㈦=E万e-t九,忡)厶酬制),)删0,)
SOe-tPg(x)isthesolutionoftheheatequation.
Since<籼0)o牵Jn(y)ei,ei>---<ei,籼(),)><锄@),ei>weget
Tr(锄∽o籼0))=<籼(x),锄(工)>
/MTrExK(,,x,石)d阳,@)=;P—f砧厶<籼(x),锄(x)>d阳z(甸
=Ee一‘k=TrL2e一’P
Definition5.3.
q(x,毒,A)∈铲(A)(u)isasymboloforderkdependingonthecomplexparameter九∈HSCif
(a)口O,考,九)issmoothin@,考,九)∈Rm×Rm×日,hascompactx-supportinUandisholomorphicin.;L
(b)Forall(口,卢,们,thereexistconstantsca,卢,',suchthat:
[DaxD拿Drxq(x,专,九)Is巳,届,',(1+l考l+l;t11/d)七一阶棚卅
Wesaythatq(x,毒,九)ishomogeneousoforderkin(考,A)if
q(x,f考,td九)=tkq(x,喜,九)fort≥1
WethinkoftheparameterAas
beingoforderd.
Lemma5.4.
(a)LetP∈掣i七一。

(u,H)fork,Z∈N.ThenforallJ∈R,thereexistsC,
sofP(允)I,,,+七≤c(1+fAI;)一,
14
(b)LetPE心(U,H)锄dlctQ∈甲2(u,日).ThereexistsRE鹄+6(【,,厅),so
thatRf=PQf。

foralll∈ro娜、.Furthermore
Proofsee【2】page
59.仃(尺)一∑謦p碟g/口!a
口LetPbeanellipticpartialdifferentialoperatoroforder
d>0whichisself-adjointandwhichhasapositivedefiniteleadingsymbolfor毒≠0.For九∈C—spec(P),Wewish
tosolvetheequation:
仃(R(九)(P一九)一J一0
InductivelyWCdefineR(A)withsymbolro+rl+…‰whererj∈s-d-j(允),and
noischosentObeverylargeWedefineE(f)=一南lye叫AR(X)dX,we
useE(t)tostudyP叫尸ForstudytheE(t),westudyitssymbol,SOwedefine
P^(f,五{)=一421i
Ze-tXrn(X,{,A)d九,thenE(t)isa甲DDwithsymboleo+el+…e一.Ifweintegratebyparts
in九础^泸一点壶Ze-tg未如¨m
Since刃dk
hishomogeneousofdegree—d一刀一kin(考,九),SOen(t,x,考)∈r”,for锄yt>0
SinceE(t)isaninfinitelysmoothingmap,thenithasasmoothkernelK,(f,工,y)Lemma5.5.Letk>0begiven.Wecanchooseno=no(k)SOthatl{(P一九)一1一R(X)}fh≤Ck(1+IXl)一七Ifl一七fon∈Hproof:see【1】1page52
Lemma5.6.
Letkbegiven.Ifnoislargeenough,WCCanestimate:lX(t,工,),)一K’(f,工,),)l。

,七SCkt七for
0<t<1
HeatEquation,EllipticComplex,HodgeDecomposition
Chapter5
即)一P-rP=一刍Ze-tx(尺(A)一(P—A)。

1)dA
Weassume0<t<1andreplacetXbyA.WeuseCauchy’StheoremtoshifttheresultingpathtyinsideHbacktotheoriginalpath?'.Thisexpress:
E(f)_e-tP_--_一27rlf.,[ve-X(尺(f一1九)一(P-t-!A)一1)t-ld九
Bylemma5.4IE(t)一e-tPI一七.七≤c.七tk~,thenbylemma3.3,wecarlgettheresult.口Weconclude晶(f)whichhassymbolen(f)isrepresentedbyakernelfunction
definedby:
畅o,工,y)=fei(x-Y)·{%(f,x,毒)d{
Deftnition5.7.
LetEbeagradedvectorbundle.Eisacollectionofvectorbundles{句).|f∈zsuchthat弓≠{O)foronlyafinitenumberofindicesj.WeletPbeacollectionofdt.Ilorderdif-
ferentialoperators弓:r(毋).÷r(弓+1)
Wesay(BE)isa
ellipticcomplexif
(a)弓+l弓=0
(b)N(aLPj)0,考)=R(aLPj—1)(五{),for考≠0.
Wedefinethecohomologyofthe
complexby:
日’陋,尸)=Ⅳ(弓)IR(Pj一1)
ChooseafixedHermitianinnerproductonthefibresofE.Weusethatinnerproduct
MtOdefineF(E).WedefineadjointsPwithtogetherwiththeRiemannianmetricon
respecttothisstructure.WeconstructtheassociatedselfoadjointLaplacian:
Aj=弓乃+弓一l曩l:r(目)_r(弓)
Theorem5.8.(HodgeDecompositionTheorem)
16
Let(P,E)bead‘horderellipticcomplex.Then:
(a)r(Ej)=Ⅳ(Aj)o弓一lr(句一1)0碍r(毋+1)asanorthogonaldirectsum.r(毋)de—
notesthesmoothsection.
(b)N(分)isafinitedimensionvectorspaceandthereisanaturalisomorphismofHJ(P,E)皇Ⅳ(~).TheelementsofN(Aj)aresmoothsectionstoEj
proof:see【6】page223
17
Chapter6LefschetzFixedPointTheorems
Chapter6LefschetzFixedPointTheorems
Letf:M_÷Mbeacontinuousmap.f'IdefinesamaponthecohomologyofMandtheLefschetznumberoffisdefinedby:
£(,)=∑(一1)pTr(广D甩片P(肘;c))
Here,weassumefissmooth,usingthedeRhamisomorphismfromHP(M;C)toHP(A,d)(thecohomologyoftheellipticcomplex:deRhamcomplex)
ForsmoothmanifoldM,thesubsetofT七Mconsistingofalternatingtensorsisdenoted
byAkM=x2MAk(TxM),心MisasmoothsubbundleofTkM,asectionofAkMiscalledadifferentialk-form.DenoteA正(肘)tobevectorspaceofthesmoothsectionofAkM.ThedeRhamcomplexis:
办:AP(M)-÷Ap+1(M)
尸:AP(M)一AP(M)bethepull-backoperation.It’Samapfromthefibreover足x)tothefibreoverx.Precisely,for卢∈Ap(肘),(广JBk仪r)=办(J)(∽x),o))
whereX=(Xl'...,而)Ⅸ∈彤∽).
Sincedf*=f’.d,f'IinducesamaponHP(M,C)笺妇r(而)/image(dp—1).
DefinetheHermitianinnerproductonthefibresofA7(肘)by<,>,andtheinnerprod-uctonA7(肘)tobe(,)=如<,>dv01.SowecandefineL2(Ap(肘))tobethecom-pletionofA7(肘)underthisnorm.Let8:AP+1(M)_AP(M)istheadjointofd.Ap=由一l昂一1+昂而:AP(M)一Ap(肘)betheassociatedLaplacian,whichisallellipticWDOoforder2andself-adjointwithpositivedefiniteleadingsymbolI喜12
Tr(f*e叫~)=Lf<P叫如广籼0),籼@)>dx
WeCanonlyconsiderjL>O,andbylemma5.1
九>CrlS,e一‘h≤Ce一。

圹,C>0andwithCauthy-Schwarzinequality,thecompactof
integraldomainandthesmoothyf,wecangetTr(广e叫Ap)<∞
WedecomposeL2(A(M))=ojL易(九)where昂(九)={驴∈Z21△Jp妒=九妒}
Let万(p,A):L2似p(肘))_昂(九)betheorthogonalprojection,werestrictf’on易(九),
18
Chapter6LefschetzFixedPointTheorems
anddefine广(p,A)=万(p,九)广:昂(.;L)_÷昂(A)
Usingthefacttheorthogonalprojection巧(p,jL)isself-adjoint,weget
Tr(f‘e一7~)=Le一‘k(广锄,妒h)=E—e一‘k(广“,x(p,厶)籼)
=∑-,ne一‰(万(p,九),’籼,x(p,厶)籼)=砀P—MTr(f'(p,A))
Lemma6.1dTr=xd
PROOF:UsethefactdA=Ad.艿A=△6
Wejustconsider办万(p,A)=x(p+1,A)彩
If妒∈三≥(A),万妒=妒,△d≯=d△妒=Ad△妒,SO万d妒=de=d万驴
If妒∈E0(九)上,万妒=O,(de,y)=(妒,6lf,)foranylf,∈E_+l(A),
△6y=6△V,=gSW,soSW∈昂(A)SO(de,y)=(妒,6y)=o,兀d妒=0=d万妒
Fromxf*d=xdf*=dxf*,weget厂(p,A)d=df*(e,A),So
Lemma6.2∑p(一1)pTr(广(p,九))=0for允≠0
PROOF:Firstweshowthatwhen九≠o,ker(dpl昂(九))=image(dp一1I易一l(九))
ford2=O,wejUStshowneedtoshowker(dpI岛(九))∈image(dp一1I昂一l(jL))
For妒∈ker(dpl£_(A)),△驴=0,de=0,SOd6妒=九妒,妒=l/九d6妒,
fbr△6妒=6△妒=A6驴,SO6妒∈E_一1
ForfixedA≠0,wejustuse矗represent广(p,A)forsimplenotation.
而:妇纬_+妇纬,SOTdeducethequotientspacemap,stilldenotedbyfp:Ep/ke,'ep_
EpIkerd,,
For昂=ker(dpI昂)oF,whereF2e/妇rdp竺imase(dpI易),
forfpd=dfp,image(dpI酃)isalsotheinvariantsubspaceof昂.Although,Fofcourse
maynotbeinvariantunder易,butwehave:fordim(Ep(九))<∞,foranyfixA≠O,choosebasesofker(dpI易)denotedby{el'...锹),enlargethemintothebasesofEp,denotedby{el,…ek,gl,…,勘),SOweget:
厶ce-,…寥七,g·,…,g,,=cP-,…锹,g-,…,g,,A三)
而cg-,…,g,,=c舌·,…P七,g-,…,g,,(三)
Wheng/inep,wedenote【g】isthenaturalimageinEp/妇rdp,and{【gl】'...,【gt]}isalsothebasesofEp/kerdp,and
易([gl】,…,kf】)=(kl】,…,【g,】)D
SOweget
Trfp=TrA+TrD=Tr(fplkerdp)+Tr(厶lep/妇,.dp)=rr(Al妇啡)+Tr(易limage(dp))Sinceker(dpI易(A))=image(dp一1I昂一1(九))for九≠o,
wegetI:p(-1)pTr(A)=0
ForA=o,ep(o)=kerAp竺ker(dp)/image(alp一1)byHodgedecompositiontheorem,Ep(-1)PTr(f'(p,o))=∑p(--1)PTr(f*onHP∽,c))=£(丁)
SinceEp(一1)pTr(f'(p,A))isafinitesumandtheabovelemma,weget
L(,)=∑e叫A
AEl-1)prr(f*(p,jL))P
=E(-1)pEe—MTr(f(p,九))
PA
=∑(一1)PTr(.f*e叫~)

Remark:
Fromtheabovediscussion,wecarlcomputeL(Dbythemethodofheatequation.
ThiscomputationabovewaspurelyformalanddidnotdependthefactweweredealingwiththedeRhamcomplex.Sowecangetmore.
Lemma6.3Let(EE)beanpartialdifferentialellipticcomplexoverMandletf:M_M
besmooth,finducethemapf*:r(E)一÷r(广(E)),wheref*(E)=工勘{工)×毋“)bethepull-backbundle.Thatis:a∈r(E),(,’口)@)=tr(f(x))Weassumegivenlinear
maps咖:Ei,,伍)_Ei,x,SOwedefineE+=咖。

广:r(e)_r(E),suchthatP/F/+=F毋
Chapter6LefschetzFixedPointTheorems
aboutthevectorbundle局.Thenland咖induceamaponH‘(只E),Wedefine
L(f)p=∑(一1)‘Tr(F‘onH‘∽E))
.ThenwecomputeL(f)p=∑f(一1)‘Tr(r+e一’A‘),whereAi=芹毋+毋一l肇listheas-sociatedLaplacian.
TogetalocalformulaforL(f),wemustplacesomerestrictionsonfWeassumethefixedpointsetoffconsiststhefinitedisjointunionofsmoothembeddedsubmanifold^毛.Thatisfix(f)={工∈MIf(x)=工)=U;:l^霸,whereM/n^乃=o,fori≠j,andlis
afiniteinteger.id:尬qM.Wcidentify瓦晒andid。

瓦M,SOfor坛∈M/,瓦尬C瓦M淞vectorsub-space.Wedenotethequotientspace硒Nx尬=TxM/TxMi.^:瓦M---9巧(曲爿肘.Since^=id。

on了≥尬,SO五:瓦慨-÷瓦尬舔invariantsubspacc,anditin-ducesamapANonM.Wesupposedet(1一^Ⅳ)≠0私anon-degeneracycondition.
IfKisthekernelofe-tP,meanse-tPg(x)=fK(t,x,y)g(y)dvol(y),
F。

e一‘P90)=fOxK(t,,(工),y)g(y)dvol(y),where以:E’(工)—}最islinearmapdefinedabove.WeuseF‘KtodefinethekernelofF*e—tP.
Lemma6.4LetPbeanellipticpartialdifferentialoperatoroforderd>0whichisself-adjointandwhichhasapositivedefiniteleadingsymbolfor考≠0.Letf:M—Mbeasmoothnon-degeneratemapandlet妒:辱厂(j)--+最beasmoothvectorbundleho-momorphism.WedenoteF’=币of:r(e)---9r(广(£))--}r(£).IfKisthekernelofe一俨thenrr(F+e一沪)=如Tr(F‘K)(f,j【,x)dvol(x).
(a)Iffhasnofixedpoints,ITr(F‘e-tP)I≤G,asforanyn,for0<t<1
(b)IfthefixedpointsetoffconsistsofsubmanifoldMiofdimensionmi,wewillcon-structscalarinvarianta—x)whichdependfunctionallyuponafinitenumberofjetsofthesymbolandoff.Thean0)aredefinedoverMand
Tr(F+已-,P)“军n∑=Of!字厶锄。

)d阳ff@),甜f-÷o+
f一』W
dvoliO)denotestheRimannianmeasureonthesubmanifold.
Itfollowsfrom(a)thatiffhasnofixedpoints,thenL(f)v=0
2l
Chapter6LefschetzFixedPointTheorems
PRooF’:
F+e叫尸:r(e)一r(e)issmoothlinearoperator.ForanychartUofmanifoldM。

any9,lf,∈C孑(u),wehaveee一俨v/g(x)=fe‘o—y)‘言p@,{)g(),)州考whereg∈I'(E),andp(x,考)∈r(u,E)about)【'andF+ape一泸惦0)=fe‘(厂(善)_)。

{识p(,(x),考)g◇)d妒考,For{J∈Vlf(x)g∥),p(厂(z),考)--o,sowejustconsider(xlf(x)∈∥),sof(x),yEU,and,0)-ycanhaveitsmeaningintheaboveintegral.
FromtheatlasofcompactmanifoldM(acollectionofchanswhosedomainscoverM),wechoosefiniteopensub·cover,denotedby{%),Andlet{|}l口:M_÷尺)betheunitypartialof{Ua},F’e一俨=蜀.jhiF。

e一护hjandwelocatetheproblemontheU--thesup-portofhihj
Letrn(symb01),en(symb01),Kn(kernel)bedefinedinsection5.ByLemma5.6lF+K—L≤,10F·妫I电k≤c(k)t置0<t<1,foranykifno=,10@).ThatisforVlargek,t七bes-mallenough,WeCanfindfiniteT‘畅toapproximateT4Ktoarbitrarilyhighjetstk.SowecanreplaceKby翰inproving(a)and(b)
(a)Werecallthat:
en(t,J,考)=一2嘉iJ,e-tj.h@,考,九)d九
Weusern’shomogeneityoforder—n—d
f三+1%(z,f5{,A)=(t-;)-n-dr.(x,f;{,九)=h@,考,t一1九)
Weassume0<t<1andmakea
changeofvariablestoreplacetAbyA.WeuseCau.thy’StheoremtoshifttheresultingpathtyinsideRbacktooriginalpath7.So
en(t,工,喜)=一南一∥砌仅,考,f一1A)f_1dA=一f吕赤矗P—A%0,f{,A)=f署%仁,f5考)WcdefineenO,{)=en(1,工,考)∈S-',whichisindependentoft.Then
而(f,X,Y)
=fe‘“-y)‘en(t,工,g)dg=fei(x-y)‘即en(x,,5考)必=f等,∥(工一y).,-缸en(X,毒)砧
SoF‘%(f,石,x)=f了R--Illfci(f(J)一工)‘7一者二做P一(厂(石),{)d{
ForestimateTr(F’%)(f,工,工),westudytheterm
fe‘(,(对一工)‘7一a*Tr(,xe.(rx,{))d考dLwhere(x,{)∈E(M)
SinceMiscompact,andfO)≠工foranyx∈M.RecallthatwehavelocateitonchartU,andiff(x)簪U,en(f(x),考)=O,SOwejustconsiderf(x)∈U,andf(x)≠工hasitsmeaning.SowewecanboundIf(x)一工I≥£>0,inthedomain.
,P‘(,(工)一J)。

’’a毒Tr(饭%(厂0),考))d毒dk=
Chapter6
LefschetzFixedPointTheorems
,罐el(f(x)一工)raelf(x)一xl~t警Tr(0xe疗(,0),毒))d考出
=fei(f(x)一J)4-{I,(x)一xr-放f警罐Tr(以P玎(,0),喜))必出
Sinceen(x,毒)∈S-**,soA{Tr(#pxen(f(x),考))absolutelyintegralabout考SOwecanboundtheintegralbyC(n,k,e)t‘,foranyk,for0<t<1
(b)Wecanlocalizetheintegraltoarbitrarilysmallneighborhoodofthefixedpointsetinproving(b).Weshallassumefornotationalsimplicitythatthefixedpointsetoffcon-sistofasingleembeddedsubmanifoldMlCMofdimensionm1.Thatis,foreachpoint工∈MI,thereisanopenchart(U,lI,)ofM,suchthat
lf,(UNMI)=.【Ol,…,.确l,aml+l,…,am)∈u/(u):aml+l=0,…,am=0))
Wecanchoose(Ur'lM!,伍1'--.,Xml)asthechartof肘l,thenVx∈MICM,wehavethetangentspace,TxMIC瓦肘,
thepushforwardmap吖(=^):瓦肘--yTxM(becausea∈MlCfix(t)).WedenoteVi=暑asthebasesofTxM,sincedT=id,:瓦尬一瓦尬,wehave:
打cⅥ….,‰。

,%。

扎…,‰,=c川….,wm。

,wm。

扎…,wm,(。

I三)
Asthenon-degeneracycondition,det(1一d劢)≠0,wehavedet(1-A)≠0,wedefine曲ebasechangematr政日=(。

1三,whereD=I-A,C=-B.
Because(三艺二:。

)(三:)(三三)=(三三)
ThisgiveadirectsumdecompositionoverUNMI:
州=驯l。

心andⅣ=(。

I蛳0)衙虮叩确
Locally,weCallchooseaRimannianmetricoverUnMI,suchthatthissplicingisor-
thogonal.Usingpartitionofunity,wecanconstruct
global
RiemannianmetriconMl
Wedescribethe
geometrynearthefixedmanifoldMI坛∈MiweCanchooselocalchart
(y=UNMI,(),l’.…YmI,YmI+l’.…蜘),wedenotewi=蕞suchthatTxMI=span{wl'...Wml),andM=span{wml+I….‰),whicharebothinvariantunderd,'
df=,o蛳and{wml+l….Wm}areorthonormal.Locally,weconsidertrivialnormal
bundleoverVCMI—NvMl=Ux∈y{工)XM.Let(),l….,ymIbelocalcoordinateson
6LefschetzFixedPointTheorems
Chapter
MI,and{‰I+l’...‰)bealocalorthonotrnalframeforNvMI.Weusethislocalor-thonormalframetointroducefibercoordinatesz=(ZmI+l,…Zm)forNvMlbydecom=posinganyW∈NvMlintheform:W=EjZjwj(y).Welet)严戗z)belocalcoordinates
forMMI.Usingexponentialmap.WedefineE:NvMI-->Mase(q,W)=exp口w,whereq∈VCMI.
Assertion:Eisalocaldifferentiablehomeomorphism
proof:E(q,o)=q,for均∈VcMI.Sincedim(NvMl)=dim(M)=m,usinginversefunctiontheorem,wejustshowtangentmapEissurjective.
Vw∈码M=码MIoⅣgW=Wl+耽,Wl∈码MI,W2∈Ⅳ覃
Forwl∈TqrMl,thereexistsmoothcurver(t)cM1,suchthatr(0)=q,f(o)=WlDenote议f)=(认f),o),E议f)=口中巾)o=认f),SOE(穸(o))=f(o)=Wl
ForW2∈Ⅳ鼋,defineot(t)=(g,tw2)乒ot(t)=exp曰(tw2),E,a(O)=w2口
Theabovediscussionislocal,butistrueforv鼋∈M1.SousethelocalnormalbundleoverMl,wecanchoose{(9,w)lq∈%CM1,W∈Nq,IWI<£旮)todiffeomorphismtoaneighborhoodof%inM.ForMiscompact,Mlthefixpointsetofsmoothmap,SOis
compact,too.Wecanchoosefini钯rclatiVeopenset%,q2{ql….,鲰)andwecanchoose£=min{el….,£七),considerthesetD(M1)={(口,W):q∈MI,W∈鹄,IWI<eo},whichisdiffeomorphismtoaneighborhoodofMlinM.Sowecanalsoregard)【-戗z)asalocalcoordinatesonM.
Wcdecomposef(x)=(^@),尼0))intosubmanifoldMIandfibercoordinates.TheJacobi锄matrixhasthefom.df(y,O)-(。

1蛳0wheredet(1-dfN)≠O,wecon-eludethatDz(厂lG)-y)仅0)=0
WeintegrateTr(F‘%)(f,X,x)alongD(MI)above.WeshallintegratealongthefibresfirsttoreducethistoanintegralalongM1.Wedefinethecotangentelementofthenor-realbundle(whichcanbcseenamanifold).Wedecompose考=.(毒l,考2)correspond-
normalbundle.Letingtothedecompositionx:=@z).D(MI)isthediskbundleofthe
W=T’D(M1)bethecotangentbundleofthediskbundle.WecanusethecoordinatesofD(M1)aslocalcoordinatesonM.WcparametrizeWby{仅z,考l,考2):…Z<eo}
M=O(MI)U(肘\)D(肘】),whichO(M1)isaneighborhoodof肘1whichdiffeomorphis-mtoD(MI)={(口,W):q∈Ml,IWl<6D},andfonM(MI)hasnofixedpintswhichisthe。

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