从积分几何的观点看几何不等式——纪念李国平院士吴新谋教授诞辰100周年

该文先介绍一些中国数学家在几何不等式方面的工作.作者用积分几何中著名的Poincarè公式及Blaschke公式估计一随机凸域包含另一域的包含测度, 得到了经典的等周不等式和Bonnesen -型不等式.还得到了一些诸如对称混合等周不等式、Minkowski -型和Bonnesen -型对称混合等似不等式在内的一些新的几何不等式.最后还研究了Gage -型等周不等式以及Ros -型等周不等式.     

Bonnesen型Ros等周不等式

首先定义了欧氏平面上的Ros等周亏格,得到了Ros等周亏格与经典的等周亏格之间的关系,讨论了Bonnesen型Ros等周不等式.利用前人的一些著名的Bonnesen型不等式,我们得到了一些Bonnesen型Ros等周不等式.     

关于曲率积分不等式的注记

本文主要研究平面卵形线的曲率积分不等式.利用积分几何中凸集的支持函数以及外平行集的性质,得到了Gage等周不等式与曲率的熵不等式的一个积分几何的简化证明;进一步地,我们得到了一个新的关于曲率积分的不等式.     

R~n中的一个Bonnesen型不等式

研究了n维欧氏空间中凸体K的等周亏格的下界估计,即Bonnesen型不等式.首先加强了Lutwak中得到的关于凸体K的p-平均不等式,用此得到一个用凸体K的均质积分及调和均质积分表示的等周亏格的下界估计.     

Ou-Pan不等式的推广形式

Ou-Pan(2010)引入了k阶宽度函数对Chernoff不等式进行了推广,本文受Ou-Pan的启发,给出平面闭凸曲线的一个新的几何不等式,进一步推广了Ou-Pan的结论,同时给等周不等式的证明提供了一种新方法.     

R3中卯形闭曲面的等周亏格的上界的注记

利用R^3中卵形结果的高斯曲率不等式以及著名的等周不等式,将R^3中卵形闭曲面的高斯曲率K应用到空间曲面的等周亏格的上界估计中,得到了R^3中卵形闭曲面的等周亏格的一个新的上界,并给出其简单证明．     

两平面凸域的对称混合等周不等式

设K_k(k=i,j)为欧氏平面R~2中面积为A_k,周长为P_k的域,它们的对称混合等周亏格(symmetric mixed isoperimetric deficit)为σ(K_i,K_j)=P_i~2P_j~2-16π~2A_iA_j.根据周家足,任德麟(2010)和Zhou,Yue(2009)中的思想,用积分几何方法,得到了两平面凸域的Bonnesen型对称混合不等式及对称混合等周不等式,给出了两域的对称混合等周亏格的一个上界估计.还得到了两平面凸域的离散Bonnesen型对称混合不等式及两凸域的对称混合等周亏格的一个上界估计,并应用这些对称混合(等周)不等式估计第二类完全椭圆积分.     

几个与Ros等周亏格相关的逆Bonnesen型不等式

研究了平面卵形区域的Ros等周亏格问题,利用R~2中卵形区域的Ros定理及其加强形式,著名的等周不等式,给出R~2中卵形区域与Ros等周亏格相关的几个逆Bonnesen型不等式.     

平面两凸域的Bonnesen型对称混合不等式

本文利用积分几何中的Poincare运动公式和Blaschke运动公式估计平面上两域K_0和k_1的对称混合等周亏格△_2(K_0,K_1),得到了对称混合等周不等式和一些Bonnesen型对称混合不等式,其中一个不等式加强了Kotlyar的不等式.此外我们还得到了一些逆Bonnesen型对称混合不等式,其条件比著名的Bottema不等式的弱.     

Gage等周不等式的加强形式

首先给出Gage等周不等式的加强形式,即证明了Gage等周不等式中等号成立当且仅当凸曲线是圆周,然后利用Minkowski支撑函数把Gage等周不等式写成关于以2π为周期的周期函数的积分不等式,它可以看成Gage等周不等式所对应的分析不等式.     

锥体积泛函与仿射不等式(英文)

本文研究了凸多胞形的锥体积泛函.利用投影体以及Lutwak、杨和张最近所建立的仿射等周不等式,得到了刻划平行四边形特征的一个崭新不等式和用锥体积泛函以及投影体的体积所表达的关于配极体体积的严格下界.     

A new affine invariant for polytopes and Schneider's projection problem

New affine invariant functionals for convex polytopes are introduced. Some sharp affine isoperimetric inequalities are established for the new functionals. These new inequalities lead to fairly strong volume estimates for projection bodies. Two of the new affine isoperimetric inequalities are extensions of Ball's reverse isoperimetric inequalities.

     

Orlicz混合相交体

本文研究了Orlicz混合相交体及其性质.利用几何分析方法提出了Orlicz混合相交体的概念,获得了Orlicz混合相交体算子的连续性和仿射不变性.通过积分方法和Steiner对称,建立了Orlicz混合相交体的仿射等周不等式.     

The role of the form body in bounds for inclusion measures

In this paper, the inclusion measures of convex bodies are studied. Some new isoperimetric‐type inequalities are established by using the technique of inner parallel bodies and mixed volumes. These inequalities give the upper and lower bounds for the inclusion measures, and show the role of the form body of a convex body in these bounds.     

Onp-quermassintegral differences function

In this paper we establish Minkowski inequality and Brunn-Minkowski inequality forp-quermassintegral differences of convex bodies. Further, we give Minkowski inequality and Brunn-Minkowski inequality for quermassintegral differences of mixed projection bodies.     

INEQUALITIES FOR Lp-MIXED CURVATURE IMAGES

Lutwak, Yang, and Zhang posed the notion of Lp-curvature images and established several Lp analogs of the affne isoperimetric inequality. In this article, the notion of Lp-mixed curvature images is introduced, Lp-curvature images being a special case. The properties and Lp analogs of the affne isoperimetric inequality are established for Lp-mixed curvature images.     

Extremal Polygons with Minimal Perimeter

In this paper we will investigate an isoperimetric type problem in lattices. If K is a bounded O-symmetric (centrally symmetric with respect to the origin) convex body in En of volume v(K) = 2n det L which does not contain non-zero lattice points in its interior, we say that K is extremal with respect to the given lattice L. There are two variations of the isoperimetric problem for this class of polyhedra. The first one is: Which bodies have minimal surface area in the class of extremal bodies for a fixed n-dimensional lattice? And the second one is: Which bodies have minimal surface area in the class of extremal bodies with volume 1 of dimension n? We characterize the solutions of these two problems in the plane. There is a consequence of these results, the solutions of the above problems in the plane give the solution of the lattice-like covering problem: Determine those centrally symmetric convex bodies whose translated copies (with respect to a fixed lattice L) cover the space and have minimal surface area.

     

Aleksandrov-Fenchel不等式及应用

本文运用Aleksandrov-Fenchel不等式,首先推广了Lutwak,Bonnesen和Fenchel等建立的三个有用的定理,这三个定理在解决某些唯一性问题中扮演着重要角色.然后,把这些结果从一般的混合体积和投影体推广到混合投影体的极和混合仿射表面积上,获得了一些较理想的结果.     

Contributions to affine surface area

Representations of equiaffine surface area, due to Leichtweiß resp. Schütt &; Werner, are generalized top-affine surface area measures. We provide a direct proof which shows that these representations coincide. In addition, we establish two theoremes which in particular characterize all those convex bodies geometrically for which the affine surface area is positive. The present approach also leads to proofs of the equiaffine isoperimetric inequality and the Blaschke-Santaló inequality, including the characterization of the case of equality.