Consider a foliate Rn-action on a compact connected foliated manifold (M,F). Let mand r be the codimension of F and the (transverse)rank of (M,F)respectively. Suppose r<m.In this paper we prove that either there ex...Consider a foliate Rn-action on a compact connected foliated manifold (M,F). Let mand r be the codimension of F and the (transverse)rank of (M,F)respectively. Suppose r<m.In this paper we prove that either there exists an orbit of the Rn-action of transverse dimension< (m + r)/2 or F can be arbitrarily approached by foliations with rank≥r+1. Moreover weshow that this kind of orbits exists in the following three cases: if F is Riemannian ;when all itsleaves are closed or if X(M)≠0(then r=0).On the other hand all foliate Rn-action on (S3,F) has a fixed leaf if dimF=1.Our result generalies a well known Lima's theorem about Rn-actions on surfaces.展开更多
Games often provide a good introduction to interesting phenomena in mathematics. In this note, we examine three variations of an iterative sharing game played around a circular (or not so circular) table. More precise...Games often provide a good introduction to interesting phenomena in mathematics. In this note, we examine three variations of an iterative sharing game played around a circular (or not so circular) table. More precisely, for each variation, we study the tendency toward equal distribution among the players. In the first variation, the players have discrete amounts at each step. The second variation removes this restriction, and the third one considers an infinitely long table with an infinite number of players.展开更多
We classify real hypersurfaces in complex two-plane Grassmannians whose structure Jacobi operator commutes either with any other Jacobi operator or with the normal Jacobi operator.
We describe the evolution of certain multiplicities and intersection numbers of plane curve singularities under the iterated action of an analytic morphism.
文摘Consider a foliate Rn-action on a compact connected foliated manifold (M,F). Let mand r be the codimension of F and the (transverse)rank of (M,F)respectively. Suppose r<m.In this paper we prove that either there exists an orbit of the Rn-action of transverse dimension< (m + r)/2 or F can be arbitrarily approached by foliations with rank≥r+1. Moreover weshow that this kind of orbits exists in the following three cases: if F is Riemannian ;when all itsleaves are closed or if X(M)≠0(then r=0).On the other hand all foliate Rn-action on (S3,F) has a fixed leaf if dimF=1.Our result generalies a well known Lima's theorem about Rn-actions on surfaces.
文摘Games often provide a good introduction to interesting phenomena in mathematics. In this note, we examine three variations of an iterative sharing game played around a circular (or not so circular) table. More precisely, for each variation, we study the tendency toward equal distribution among the players. In the first variation, the players have discrete amounts at each step. The second variation removes this restriction, and the third one considers an infinitely long table with an infinite number of players.
基金Supported by National Research Foundation of Korea(Grant No.NRF-2011-220-1-C00002)partially supported by MCT(Grant No.MTM2010-18099)supported by NRF(Grant No.NRF-2012-R1A2A2A-01043023)
文摘We classify real hypersurfaces in complex two-plane Grassmannians whose structure Jacobi operator commutes either with any other Jacobi operator or with the normal Jacobi operator.
文摘We describe the evolution of certain multiplicities and intersection numbers of plane curve singularities under the iterated action of an analytic morphism.
