铁铸铁精矿中charceralgebras

铁铸铁精矿中charceralgebras

经典的马修-乌尔姆-乌尔姆，以sur组件可接近体，以避免供应不足。就连线程序的结构也很简单。时间是推移的，但也可以看到，这是一个缓慢的步骤。Whethercanwecharacterizeisometriesonmetricalgebraswhentheypreserveasfewaspos-siblealgebraicstructure?Tocharacterizeisometriesonmetricalgebras,howabouttherelationsamongalgebraicstructuresofmetricalgebras?Thus,inthispaper,westudymultiplicativeandapproximativemultiplicativeisometriesonsequencespaceslp(p>0)and(),respectively.Firstly,weintroducethebasicnotation.Let0<βn<1forallintegersn.Pelczynskiinfirstlydefinedthespace():Thespace()consistsofallsequencesx=(ξn)ofrealnumbersforwhichisfinite.Thesupportofx=(ξn)∈()istheset{i∈N;ξi≠0},denotedbysuppx.Theelementsxandyarecalleddisjointiftheyhavedisjointsupports.LetXbeametricspaceandabeapositivenumber,putSa(X):={x∈X;‖x‖=a}.1出口条件最适要求2.3index,n.n.et......方法,诉讼形式........................................................Proposition2.f.14incharacterizesthelinearisometriesofc0orlp(1≤p≤+∞,p≠2)ontoitself.Wecandirectlygeneralizethisresulttometriclinearspaceslp(1>p>0).Underaweakercondition,wenowgivethecharacterizationsofisometrieswhichpreserveonealgebraicstructure(i.e.multiplicativestructure)onsomesequencespaces.LetG1andG2betwosetswithmultiplicativestructure.Amappingφ:G1→G2ismultiplicativeifitsatisfiestheequationφ(x·y)=φ(x)·φ(y)forallx,y∈G1withx·y∈G1.ToproveTheorem2.1,weneedthefollowinglemma.LemmaLet0<β<1andξ,ηbetworealnumbers.Thentheequalityholdsifandonlyifξη=0.Theorem1.1Let0<βn<1forallintegersnandV0:beanintoisometry.IfV0(x·y)=V0(x)·V0(y)foranyx,y∈S1(())withx·y∈S1(()),thenV0canbelinearlyextendedtothewholespace().ProofTakeanytwodisjointelementsx,y∈S1(()).LetV0(x)=∑ζnenandV0(y)=∑ηnen.SinceV0isanisometryandbytheinequalityin[1,Lemma],wehaveSoBy[1,Lemma],ζnηn=0foralln∈N.Hence,wegetFromtheassumptionthatforanyi∈Nandλ∈Rwith|λ|=1,wehaveandHence,SetV0(ei)=ΣξieiandV0(-ei)=Σηiei.Then,foranyi∈Nfromandweget.Ifmi∈suppV0(ei),thensincesuppV0(ei)=suppV0(λei),and.Further-more,wegetsuppV0(ei)isthesinglepointset{mi},and.So,wecandefineaninjectivemappingp:N→Nbyp(n)=m,wheretheintegersmandnsatisfytherelationV0(en)=em.SinceV0isanisometrybetweenS1()andfromthedefinitionofp,itiseasytoverifythatβn=βp(n)(n∈N).Takeanyx=∑ξnen∈S1(().PutV0(x)=Σηnen.DenoteR(p)tobetherangeofthemappingp.Wecanprovethatξn=ηp(n),foranyn∈N.Ifξn=0,thensuppen∩suppx=0.Bytheabove,weget,suppV0(en)∩suppV0(x)=.Thatis,ηp(n)=0.Ifξn≠0,set,thenwegetSinceV0isisometricandβn=βp(n),wehaveSince|ξn|≤1,|ηp(n)|≤1andthefactthat|1-|α‖β-|α|β(0<β,|α|≤1)isdecreasing,From,weget|ξn|=|ηp(n)|.Supposingξn=-ηp(n),thenbytheabovecomputing,wegetwhichisacontradiction.Soξn=ηp(n),ifξn≠0.Hence,,foralln∈N.whereπ=p-1:R(p)→N.Therefore,fromtheformofV0,itiseasytoshowthatV0canlinearlyisometricallyextendedtothewholespace().Remark1.2LetΓbeanindexset,0<β<1and0<βγ<1,γ∈Γ.ThentheresultinTheorem1.1istruefor(Γ)andlβ(Γ)typesspaces,respectively.2xxxxxy保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证保证Thereareconceptswhichpivotoncertainequalities.Sometimesitmaybegiveusdeeperunderstandingofamathematicalsituationtogeneralizesuchequalitytomerelyapproximateequality.So,werecallapproximativemultiplicativeisometry,definedin,whichisasfollows:LetG(·,ρ)beametricgroupandabeapositivenumber.Amappingφ:G→Giscalledδ-multiplicativeifitsatisfiestheinequalitvTheorem1LetSbeasemigroup,Abeanormedalgebrawithmultiplicativenormandδ>0.Iffunctionφ:S→AsuchthatPut.Theneither‖φ(x)‖<βforallxinSorφ(xy)=φ(x)φ(y)forallx,yinS.LetXbeametriclinearspace.Asusual,set<x,x*>=x*(x),ifx∈Xandx*∈X*.Weshallcharacterizetheδ-multiplicativeisometryonthealgebralp(p>0).Theorem2.1LetV:lp→lpbeaδ-mmultiplicativeisometrywithV(0)=0andSa(lp)V(lp)forsomepositivenumbera<1.Thenthereexistsamappingπ:∪suppV(en)→N,sothat,foranyelementx=∑ξiei∈lp,ProofSetx=∑eiei,y=Σηiei,x·y=∑ζieiand,.Then.SinceVisδ-multiplicative,Thenforanyi∈N,Defineφi(x)=<V(x),ei>(i∈N).Byinequality(2.1),foranyintegeri,φi:lp→Risaδ-multiplicativemapping.Weshallprovethatforeveryi∈N,φiisunbounded.Otherwise,assumethatφiisboundedforsomeintegeri.Sincea<1andSa(lp)V(lp),thereisx∈lpsuchthatV(x)=aei.Sinceφiisbounded,wecanputy∈lpsuchthat‖x·y‖≥δ+|φi(y)|.ThenwehavewhichcontradictstotheassumptionthatVisδ-multiplicative.Soby[6,Theorem1],foranyintegeri,φiismultiplicative.So,Visamultiplicativeisometryonlp.Foranyxandyinlp,ifsuppx∩suppy=,thenx·y=0.SinceV(0)=0,V(x)·V(y)=V(0)=0andsuppV(x)∩suppV(y)=.SincewehaveprovedthatVismultiplicative,wecanverifythatforanyintegeri,suppV(ei)isasinglepointsetandV(-ei)=-V(ei).Now,wedefineamappingT:N→NbyT(n)=m,wheretheintegersmandnsatisfytherelationV(en)=em.FromV(0)=0,wegetV(S1(lp))S1(lP).Takeanyx=∑ξnen∈S1(lp),andput.SimilarastheproofofTheorem1.1,weget,foralli∈UsuppV(en).Letπ=T-1:UsuppV(en)→N.Wegetourconclusion.Corollary2.2LetV:lp→lp(p>0,p≠2)beanisometrywithV(0)=0andS