Appl .Mat h.J.Chi ne s eUni v.Se r .B 2006,21(1):6468 PROPERTI ESOFpIJKPOLORMNOOPERNTORS PQ RSTUQ RSV W R XYZQ Y [Y RS .bUWQ N\] ^ _ ‘a ^ ccd efY gQ h WceY RhV cW i h d jg cd ecW d h Y W VekplU[ceRed gQ mecW d Q h ed VQ d WSY nW R ,Y Q Ro cd enW o.p Rk Q i h hY VQ SW RW d Q m Y q Q h Y eR ekQ ccd efY gQ h W ceY RhV cW i h d jg cd ecW d h Y W Vekl.bUWd U[ceRed gQ mecW d Q h ed V W m Q h Y eRekV cW i h d QQ RoRjgW d Y i Q md Q RSWekplU[ceRed gQ mecW d Q h ed V v Y Verh Q Y RW o.sR h UWeh UW dUQ Ro,k edplU[ceRed gQ mecW d Q h ed Vt,Y hY VV UeuW oh UQ hY kt Y V ,h . Red gQ m UW Rt Y VQ m V eRed gQ m &’ I (^ _ )*+a ^ , )( ,- gW p RuUQhk em m euV QRVQi egcm W fZY m rW d hV cQi W.~ rejRoW om Y RW QdecW d Qh edt eR- :t.0)Y k(t/,/).0k edQR[/0-.~RecW d Qh edt Y VQm V e Y VV QY oh erWceV Y h Y nW(Y RV [grem :t10)Y V h d Y i h m [ceV Y h Y nW(Y RV [grem kt Y VceV Y h Y nWQRoY RnW d h Y rm W. 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(tt ).~ pW gY 6 , d ZW Y RqY RW 7jQm Y h [Y gcm Y W Vh UQhY kt Y V8U[ceRed gQm U[ceRed gQmY kp3 152.bUWXeuRW h UW RY hY VpU[ceRed gQmk edQm m09 p: 8.TQm mQRY RnW d h Y rm WecW d Qh edt m eSU[ceRed gQmY k 2 2 m eS(t t). m eS(tt ).Tm W Qd m [,W nW d [Y RnW d h Y rm W pU[ceRed gQmecW d Qh ed Y Vm eS<1= .XW U[ceRed gQm ht3U;t;rWh UWcem QdoW i egceV Y h Y eRekt.~m jh USW oW k Y RW oh UWecW d Qh ed v3; 152 152 t t; U;t; uUY i Ui Qm m W oh UW~m jh USWh d QRV k ed gQh Y eRekt.~RecW d Qh edt Y VV QY oh e v v v 2 p d Qh edt Y VV QY oh erWplU[ceRed gQmY k;t; rWlU[ceRed gQmY k;t;.;t;.;t ;.~RecW v p 2 p . ;t; . ;t ;.~ plU[ceRed gQmecW d Qh edY VlU[ceRed gQmk edp3 1.p kt Y Vl- 1 v pv .p ,h . ,h U[ceRed gQm kt Y VplU[ceRed gQm UW Rt Y V U[ceRed gQm U[ceRed gQm UW Rt Y V 2 2 >W?Reu h UQhh UWi m QV VeklU[ceRed gQmecW d Qh ed Vcd ecW d m [i eRh QY RVh UWi m QV V W VekpegW V cW i h d jg U[ceRed gQmQRo m eSU[ceRed gQmecW d Qh ed VY R <2= QRo <3=.>W UQnW V cd ecW d h Y W Vekm eSU[ceRed gQmQRolU[ceRed gQmecW d Qh ed Vk d eg <2=QRo<4=.bQRQUQV UY Y Rh d eoji W oh UWi m QV Vekm eSU[ceRed gQmecW d Qh ed VQRo SQnWh UWW fQgcm WuUY i UY Vm eS- ,rjhRehp,h U[ceRed gQm U[ceRed gQm UjVRW Y h UW dh UWi m QV VekpU[ceRed gQmecW d Qh ed VRed 0422. wW i W Y nW o:200xyw zjr{ W i hTm Q V V Y k Y i Q h Y eR:4|}20,4|~63. :l,p,Q KW [ued oV U[ceRed gQ mecW d Q h ed V lU[ceRed gQ mecW d Q h ed ccd efY gQ h WceY RhV cW i h d jg. zjcced h W or[h UWNQ h jd Q mzi Y W Ri WQ RoEoji Q h Y eRFejRoQ h Y eRekZW RQ Rcd enY Ri W. . Y^dgxh^dgs e d,e t^l 65 PROPERTI EsOlpωHYPONORMApOPERATORs t hec l as sofl oghyponor malope r at or sc ont ai nst heot he ronei n[5].Theaut hors howe d ,buti t hati fT i saTanahas hiope r at oronH,t he nT⊕0onH⊕H i sωhyponor mal ti snot phyponor malorl oghyponor mali n [4].Thus t he c l as s ofωhyponor malope r at or s .Put pr ope r l yc ont ai nst hec l as s e sofphyponor maland l oghyponor malope r at or s nam pr ove dt hes pe c t r um pr ope r t i e sofhyponor malope r at or si n[6].Re c e nt l y,i n[7]and[8], .I t hepr ope r t i e shavebe e ne xt e nde dt ophyponor malope r at or s n[9]and[10],Al ut hge .I ,wes hase xt e nde dt he mt oωhyponor malope r at or s nt hi spape r hal le xt e ndt he mt opω- hyponor malope r at or sandc ons i de rt her e l at i onoft hes pe c t r aandnume r i c alr angeofpω- .Att hyponor malope r at or s hee nd,f ort hepωhyponor malope r at orwes hal lpr ovet hati f ~ ~ ,t Ti snor mal he nT=T. PQ RST UV W X YZ [ X T‘oft he Ac ompl e xnumbe r\i ss ai dt obei nt heappr oxi mat epoi nts pe c t r um ] ^_ ope r at orT i ft he r ei sas e aue nc ebcdeofuni tve c t or ss at i s f yi ng_Tf \‘cdg 0,andi fi n h i ‘cg0,t addi t i on_T f\ he n\i ss ai dt obei nt hej oi ntappr oxi mat epoi nts pe c t r um ] _T‘ d k ^ oft heope r at orT.Theboundar yoft hes pe c t r um ofanyope r at orT i sas ubs e toft he appr oxi mat epoi nts pe c t r um ]^_T‘oft heope r at orT.loranybounde dl i ne arope r at or sm .pe andT,i ti snnownt hatt henono e r opoi nt sof]_mT‘and]_Tm‘ar ei de nt i c al tT=qrTr h h h bet hepol arde c ompos i t i onofT.si nc erT r= qrTrq ,rTr= q qrTr,t henono e r o h . poi nt sof]_rT r‘and]_rTr‘ar ei de nt i c al [9] ,\ wx.I tW uuSQ.v. pe tTbes e mi hyponor mal ft hes e aue nc ebcdeofuni tve c t or si ss uc h h i ‘cdg0,t ‘cdg0. t hat_Tf\ he n_T f\ [11] ,\y 0.I tW uuSQ.Q. pe tT beωhyponor mal ft hes e aue nc ebcdeofuni tve c t or si ss uc h h h i ‘cdg0,t r‘cdg 0.I ‘cd he n_rT rfr\ fi naddi t i onT i si nve r t i bl e,t he n_T f \ t hat_Tf\ g0. ,\y 0.I z{W |V W u Q.}.pe tT bei nve r t i bl epωhyponor mal ft hes e aue nc ebcdeofuni t h i ‘cdg0,t ‘cdg0. ve c t or sar es uc ht hat_Tf\ he n_T f\ p ~p ~h p ~ p .lorap~V ||f ωhyponor malope r at orT,wege trTr ≥ rTr ≥ rT r.ThusT i s 2 ~ . hyponor malandT i sωhyponor mal ‘cd‖≥r\ rf‖Tcd‖,wi si nc e‖_Tf\ t houtl os sofge ne r al i t y,weas s umeTy0.pe t 1 b‖ Tcd‖ e= b‖ rTrcd‖ ebebounde dawayf r om 0.pe tyd= rTr2cd,t he nb‖ yd‖ ei s bounde dawayf r om 0. 1 1 ~ ~f ‘ g 0. ,_T si nc e_Tf \‘cdg 0,t he n_TrTr2f rTr2\‘cdg 0,t hati s \ yd Byus eof ~h i ~p ~h rpfrrp‘ g0. ‘ydg0,s rp‘ydg0,and_rT pe mma2.2,_T f\ o_rTrfr\ \ yd ~p ~h p p lorpωhyponor malope r at orT,wege trTr≥rTr≥rT r,t he n ~h p ~p ~h p p p 0≤ __rTr f rT r‘yd,yd‘≤ __rTr f r\ r‘yd,yd‘f __rT r f r\ rp‘yd,yd‘g 0. .Mat .B Appl h.J.Chi ne s eUni v.Se r 66 .21,No.1 Vol ~* p p He nc e(|T|-|T |)yn→0,and ~ ~ (|T|p - |λ |p)yn = (|T|p - |T* |p)yn + (|T* |p - |λ |p)yn → 0. 1 p p |)xn→0. Thus|T|2(|T|-|λ p |p)xn→0.ThusU|T|1- p(|T|p-|λ |p)xn→0,t Si nc eT i si nve r t i bl e,t he n(|T|-|λ hat |p)xn→0,s -|λ |pU|T|1- p)xn→0. ,(T-U|T|1- p|λ o(λ i s * p- 1 - i θ * 1- p -i θ ,U* xn- |λ|p- 1e |T|1- pxn→ 0, Be c aus eU xn- |λ| e U U|T| xn→ 0,t hati s * p -i θ |pxn→0.ThusU|T|U* xn-|λ |xn→0,t ,TU* xn-e hati s Txn→0, t he n(U|T|U )xn-|λ * -i θ * -i θ * nc eT i si nve r t i bl e,t he n(U -e )xn→0.ForT=U|T|,U T= andT(U -e )xn→0.Si * * * * * U U|T|=|T|.ThusT xn=|T|U xn=U TU xn. * - 2i θ -i θ * ,(T* -|λ |e )xn→0,t )xn→0. Be c aus eT xn-e λ xn→0,t hati s hus(T -λ ,t T)-0. Cor ol l ar y2.4.Le tT bei nve r t i bl epωhyponor mal he nσja(T)-0=σ a( Le mma 2.5.Le tT= U|T|bet hepol arde c ompos i t i onofT,λ∈ C,{xn}i st heve c t or * * )xn→0and(T -λ )xn→ 0,t |)xn→ 0and(|T |- |λ |)xn s e que nc e.I f(T-λ he n(|T|- |λ -i θ i θ * -i θ →0.I =|λ |e ≠0,t fλ he n(U-e)xn→0,(U -e )xn→0. * .Foranyx∈H,‖Tx‖=‖|T|x‖,t Pr oof he nTxn→0⇔|T|xn→0.Si mi l ar l y,T xn→0⇔ |T* |xn→0,t ,λ =0,t hati s hi sr e s ul ti st r ue. -i θ =|λ |e ≠0,t |and|T* |+|λ |ar Le tλ he npos i t i veope r t or s|T|+|λ ei nve r t i bl e, * * (|T|+ |λ |)(|T|- |λ |)= T (T- λ )+ λ (T - λ ), * * * (|T |+ |λ |)(|T |- |λ |)= T(T - λ )+ λ (T- λ ). * * )xn→0,t |)xn→0,(|T |-|λ |)xn→0, )xn→0,(T -λ hus(|T|-|λ So(T-λ i θ |λ |(U- e )= (T- λ )- U(|T|- |λ |), * -i θ * * * |λ |(U - e )= (T - λ )- U (|T |- |λ |). i θ * (1) (2) (3) (4) -i θ The n(U-e)xn→0,(U -e )xn→0. i θ ,λ= |λ|e ≠ 0,{xn}i st heve c t or Cor ol l ar y2.6.Le tT bei nve r t i bl epωhyponor mal i θ )xn→0,t |)xn→0and(|T* |-|λ |)xn→0;So(U-e )xn→0, s e que nc e,(T-λ he n(|T|-|λ -i θ (U* -e )xn→0. : Re c al lt henume r i c alr angeW(T)ofT wi t hi t sde f i ni t i onasf ol l ows W(T)= {(Tx,x):x∈ H,‖x‖ = 1}. Le tW (T)bet hec l os ur eofW(T).Foranyope r at orT,asweal lknow,W(T)i sac onve x ,t s e tandσ(T)⊆W (T).I fTi snor mal he nW (T)=c onv(σ(T)),whe r ec onv(σ(T))me ans t hec onve xhul lσ(T). 1 1 ~ [9] Le mma2.7 .Le tT=U|T|bet hepol arde c ompos i t i onofT.T=|T|2U|T|2,t he nσ(T) ~ =σ(T). [9] - ~ - ~* ,t Pr opos i t i on2.8 .Le tT beωhyponor mal he nW (|T|)⊆W (|T |). ~|)⊆W ~* |). -(|T -(|T ,t The or e m 2.9.Le tT bepωhyponor mal he nW ~p ~* p ~ ~~ p .ForapPr oof ωhyponor malope r at orT,wehave|T|≥|T|≥ |T |.Le tT=U|T|be ~ ~* ~ ~ ~* ~ ~ ~* ~ ~* ~ ~ t hepol arde c ompos i t i onofT,t he n|T |=U|T|U ,|T|=U U|T|,andσ(|T|)=σ(U U . YangChangs e n,e tal PROPERxr ESOFpωHYPONORMALOPERAxORS 67 ~|)= (~|~|~* )= (|~* |), ~ ~* ~p |T σU T U σ T t husσ(|T|)- {0}= σ(|T |)- {0}.Be c aus eof|T|≥ ~* |p, ~ ~* ~ ~* ~|)=c ~ -(|T |T t he n0∈σ(|T|),σ(|T |)andσ(|T|)⊆ σ(|T |),t husW onvσ(|T|)⊆ ~* - ~* c onvσ(|T |)=W (|T |). ~|p)⊆W ~* |p). -(|T -(|T Re mar k.Wi t hc ar e f ulobs e r vat i onweknow t hatW ~ ~ p * p ,t The or e m 2.10.Le tT bepωhyponor mal he nσ(|T|)⊆W(|T |). .ForapPr oof ωhyponor malope r at orT unde ranyx∈H, ~p ~ p (|T|x,x)≥ (|T|x,x)≥ (|T* |px,x), (5) ~ ~ ~ p p * p t he n(|T|x,x)∈W(|T|)⊆W (|T |). ~* p ~* |p).An p -(|T t(|T|x,x)∈W dhe nc e Byus eoft hec onve xi t yofW(|T |)and(5)wege ~p p - ~p - ~* p σ(|T|)⊆c onv(σ(|T|))=W (|T|)⊆W (|T |). ef gohi j klm hnr e mar k o Forωhyponor malope r at or swehaveknownt hef ol l owi ngr e s ul t s ~ * * ,t (p)Le ,qe rT.r fT i snor mal he n tT beωhyponor mal rT⊆qe rT orqe rT ⊆ qe ~.( T=T s e estu,vor ol l ar yt). ~ ~ (w)Le ,i ,t tT beωhyponor mal fT i snor mal he nT=T.(s e espwu,xhe or e m p). ,and pr We s hal le xt e nd (w) t o pωhyponor malope r at or s as f ol l ows e par et he . f ol l owi ngLe mmasf i r s t * * * * * * ye mmaf.1.Le tz=z ,{={ ,|(} )~|(z)and|(} )~|({).r f} z}=} {}, t he nz={. * * * * .Si Pr oof nc e} z}= } {},t he n(z}x,}x)= (} z}x,x)= (} {}x,x)= ({}x, }x).Be c aus ez|R(})={|R(}),s oz|R(})={|R(}). * * Si nc e|(} )~|(z),|(} )~|({),t he nz||(}* )={||(}* )=0.xhusz={. p p w p p w ye mmaf.2.Le tz,{≥0.r f{wz{w={ andzw{zw=z ,t he nz={. . Pr oof p p p w w p Si nc e{wz{w={ ,t he n(z{x,{x)= ({z{x,x)= ({w{ {wx,x)= ({{x,{x),t hus z|R({)= {|R({),andz|R({)= {|R({).Now f oranyx∈ |({),be c aus e({zx,{zx)= (x, w t ,{zx=0. z{ zx)=(x,{ zx),t he n({zx,{zx)=0,t hati s p p w t t ,x∈ |(z )= |(z),t Si nc ezw{zw= z ,t he nz x= z{zx= 0,t hati s he n|({)~ |(z).Byus eofLe mmat.p,wehavez={. ~ ~ ,0<p≤p.r ,t The or e m f.f.Le tT=U|T|bepωhyponor mal fT i snor mal he nT=T. ~ ~* ~ ~~* ~|w=|~* |w. .Si ,t ,|T Pr oof nc eT i snor mal he nT T=TT ,t hati s T Fort hepωhyponor mal ~ ~ ~ ~ p p * p * ope r at orT,|T|≥|T|≥|T |,t he n|T|=|T|=|T| . p p ~|=| * w * * (p)|T T|i fandonl yi f|T |=|T |w|T||T |w. p p p p * w * ~ ,s r nf ac t i nc e|T|= |T|,t he n|T|wU |T|U|T|w= |T|,t he nU|T|wU |T|U|T|w p p * w * ,|T* |w=|T* |w|T||T* |w. U =U|T|U ,t hati s 68 .Mat .B Appl h.J.Chi ne s eUni v.Se r .21,No.1 Vol . Whatwi l lbeont hec ont r ar y,i ti sde arandobvi ous 1 1 ~* 2 * (2)Si mi l ar l y,|T |=|T|i fandonl yi f|T|=|T|2|T ||T|2. 1 1 1 1 ~ ~* * * * Si nc e|T|=|T|=|T |,t he n|T |2|T||T |2=|T|2|T ||T|2.Byus eofLe mma ~. 3.2,(1)and(2),wehave|T* |=|T|and|T|U=U|T|,he r c eT=T Re f e r e nc e s 1 Al ut hgeA.Onphyponor ma lope r a t or s0<p≤1,I nt e gr a lEqua t i onsOpe r a t orThe or y,1990,13:307315. 2 Al ,I 10. ut hgeA,Wa ngD.ωhyponor ma lope r a t or s nt e gr a lEqua t i onsOpe r a t orThe or y,2000,36:13 Al ,1999,2: ut hgeA,Wa ngD.Anope r a t ori ne qua l i t ywhi c hi mpl i e spa r a nor ma l i t y,Ma t hI ne qua lAppl 113119. 4 Al ut hgeA,Wa ngD.ωhyponor ma lope r a t or sⅡ,I nt e gr a lEqua t i onsOpe r a t orThe or y,2000,37:324331. 5 Ta ,I 372. na ha s hiK.Onl oghyponor ma lope r a t or s nt e gr a lEqua t i onsOpe r e a t orThe or y,1999,34:3646 Put ,Tr ,1974,188: na m CR.Spe c t r aofpol a rf a c t or sofphyponor ma lope r a t or s a nsAme rMa t hSoc 419428. 7 ChoM,Hur ,Gl uyaT,I t ohM.Spe c t r aofc ompl e t e l yphyponor ma lope r a t or s a s ni kMa t h,1995,30:6167. -M,I 8 Cho ,Pr ,1995,123: t ohM.Put na m' si ne qua l i t yf orphyponor ma lope r a t or s ocAme rMa t hSoc 24352440. 9 Al ,Hokka ut hgeA,Wa ng D.Put na m' st he or e ms f or ωhyponor ma l ope r a t or s i do Ma t he ma t i c a l ,2000,29:383389. J our na l 10 Al ,Hokka ut hgeA,Wa ngD.Thej oi nta ppr oxi ma t epoi nts pe c t r um ofa nope r a t or i doMa t he ma t i c a l ,2002,31:187197. J our na l 11 Xi ,Bos aD.Spe c t r a lThe or yofHyponor ma lOpe r a t or s t on:Bi r kha us e rVe r l a g,1983. 12 ChoM,Hur ,JofI ,2002,7(1):110. uyaT,Ki m Y O.A not eonωhyponor ma lope r a t or s ne qua lAppl .ofMa De pt t h.,He na nNor ma lUni v.,Xi nxi a ng453007,Chi na.