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Sphere Willmore Hypersurface Overall Pinching Theorem

Posted on:2008-09-29Degree:MasterType:Thesis
Country:ChinaCandidate:H C ChenFull Text:PDF
GTID:2190360215992183Subject:Basic mathematics
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Let M be an n-dimensional(n≥3)compact minimal submanifold in n+p-dimensional unit sphere Sn+p.H denotes the mean curvature of M,S denotesthe square of the length of the second fundamental form.Then we have:If S≤n/2-1/p, Then either S≡0,and M is totally geodesic,or S≡n/2-1/p. Inthe latter case.1.either, p=1and M is a Clifford torus Cm,n-m in Sn+1.2.or n=2, p=2 and M is the Veronese surface in S4(1).After that,[2] [4] [6]improved the pinching condition. Recently, H.Z.Li, ob-tained the following results when M is a Willmore submanifolds (see [3] [5] [9])Theorem: Let M be an n-dimensional(n≥2) compact Willmore subman-ifold in n+p-dimensional unit sphere Sn+p. then we have integral from Mρn(n/2-1/P-ρ2)dv≤0In particular,if 0≤ρ2≤n/2-1/pthen eitherρ2=0 and M is totally umbilical, orρ2≡n/2-1 p. In the lattercase,either p=1 and M is a Willmore torus Wm,n-m defined by the followingequation: Wm,n-m=Sm n-m/n1/2×Sm-m m/n1/2,1≤m≤n-1. or n=2,p=2 and M is the Veronese surface.Obviously, all the above results have pointwise condition for S or S-nH2 Itseems to be interesting to study the Lq-pinching theorem. It is first initiated byC.Li.Shen[8], latter H. Wang[16], J. M. Lin C. Y. xia[7], H. W. Xu[9] improvedthe theorems.In this thesis, when M is Willmore compact hypersurface we proved.Theorem. Let M(n≥3)be n-dimensional compact Willmore hypersur-face in unit sphere Sn+1. H Denotes the mean curvature of M and S denotes the square of the length of the second fundamental form.if‖ρ2‖n/2<n(n-2)3/C2(n)[n3(n-1)2+(n-2)3(1+H02)]Where H0=(?) H.Thenρ2=0, ie M is totally umbilical hypersurface inSn+1.
Keywords/Search Tags:Hypersurface
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