Classification Of Compact Minimal Legendre Submanifolds With Non-negative Sectional Curvature In 9-dimensional Unit Sphere

In this thesis,we study the classification problem of n-dimensional compact minimal Legendre submanifolds with non-negative sectional curvature of(2n+1)dimensional unit sphere S2n+1(1).By using C-paxallel second fundamental form and Ricci identities,we have obtained the classification about 4-dimensional compact minimal Legendre submanifold with non-negative sectional curvature of 9-dimensional unit sphere,is either a totally geodesic submanifold,or isometric to T4,or isometric to S1×S3(2/(?)),or isometric to T2×S2((?)),the immersion expressions of submanifolds are further given.