与给定线段相交的定长线段的运动测度公式及其应用

本文研究了凸多边形的运动测度的表达式,利用线段将已知其包含测度的凸多边形分划成其它的凸多边形,通过计算出与给定线段相交的定长线段的运动测度公式,从而得到某些凸多边形的运动测度的具体表达式,并把它应用到几何概率问题中,获得一个新的几何概率结果.     

一类特殊网格的几何概率

本文研究了以正六边形和菱形为基本区域的复合网格中的Buffon问题.利用积分几何理论和运动测度工具,获得了上述复合网格与长针相交的概率表达式,推广了长针与复合网格相交的概率问题.     

一类特殊网格的几何概率

本文研究了以正六边形和菱形为基本区域的复合网格中的Buffon 问题. 利用积分几何理论和运动测度工具, 获得了上述复合网格与长针相交的概率表达式, 推广了长针与复合网格相交的概率问题.     

正三棱柱的Buffon投针问题

本文研究了正三棱柱有界网格的Buffon投针问题.利用限弦函数和限弦投影函数两个工具,获得了正三棱柱运动测度的具体表达式及一个新的几何概率结果.     

利用不变测度消除Bertrand奇论

通过不变测度的引入,消除了Bertrand奇论.     

三角形网格的有效性分析

本文分析了利用三角形网格对π作统计估计的有效性,首先对任意三角形网格进行一般性的分析,得出了具体的表达式,又对等边三角形网格和等腰直角三角形网格两种特殊情形进行具体计算,得出了具体的数值.     

R3中双弦幂积分

本文研究R3中凸体的双弦幂积分,利用线偶的运动密度,得到了一些性质及球体上的部分双弦幂积分值,并由此解决了R3中一几何概率问题.     

复杂网络的Buffon概率问题

本文研究了两种复杂网格的几何概率问题,通过利用凸域内定长线段的运动测度,得到了这两种复杂网格的Buffon概率.     

Strongly 1-Bounded Von Neumann Algebras

Suppose F is a finite tuple of selfadjoint elements in a tracial von Neumann algebra M. For α > 0, F is α-bounded if where is the free packing α-entropy of F introduced in [J3]. M is said to be strongly 1-bounded if M has a 1-bounded finite tuple of selfadjoint generators F such that there exists an with . It is shown that if M is strongly 1-bounded, then any finite tuple of selfadjoint generators G for M is 1-bounded and δ₀(G) ≤ 1; consequently, a strongly 1-bounded von Neumann algebra is not isomorphic to an interpolated free group factor and δ₀ is an invariant for these algebras. Examples of strongly 1-bounded von Neumann algebras include (separable) II ₁-factors which have property Γ, have Cartan subalgebras, are non-prime, or the group von Neumann algebras of . If M and N are strongly 1-bounded and M ∩ N is diffuse, then the von Neumann algebra generated by M and N is strongly 1-bounded. In particular, a free product of two strongly 1-bounded von Neumann algebras with amalgamation over a common, diffuse von Neumann subalgebra is strongly 1-bounded. It is also shown that a II ₁-factor generated by the normalizer of a strongly 1-bounded von Neumann subalgebra is strongly 1-bounded. Received: November 2005, Revision: March 2006, Accepted: March 2006     

The indicator of contact boundaries for an integral geometry problem

We pose and study a rather particular integral geometry problem. In the two-dimensional space we consider all possible straight lines that cross some domain. The known data consist of the integrals over every line of this kind of an unknown piecewise smooth function that depends on both points of the domain and the variables characterizing the lines. The object we seek is the discontinuity curve of the integrand. This problem arose in the author’s previous research in X-ray tomography. In essence, it is a generalization of one mathematical aspect of flaw detection theory, but seems of interest in its own right. The main result of this article is the construction of a special function that can be unbounded only near the required curve. Precisely for this reason we call the function the indicator of contact boundaries. A uniqueness theorem for the solution follows rather easily from the property of indicators.     

凸域内矩形的运动测度

本文研究了凸域内矩形的运动测度,通过对凸域内定长线段运动测度的推广,建立了包含在凸域内且长、宽都确定的矩形运动测度的一般公式,利用此公式得到了圆域和矩形域内此类矩形的运动测度,并以此为基础得到了推广后的Buffon投针问题的一些结果.     

2.5维介质Born近似波速反演唯一性

考虑脉冲源引起的２．５维弱不均匀介质波速反演问题，利用线性化方法得到了波速的二维小扰动满足的积分方程，这是一个积分几何的问题，进而由Ｆｏｕｒｉｅｒ变换和脉冲函数的性质将此二维积分方程化为单变量的积分方程，最后用压缩映象理论证明了积分方程解的唯一性。本文给出了二给波速反演的一种新算法。同时，唯一性结果证明了已有的迭代算法的合理性。     

Remarks on a Translative Formula for Sets of Positive Reach

An example of a pair of sets of positive reach is presented, violating a condition assuring the intersection of these sets to have positive reach for almost all translations of one of these sets. The same condition ensures the validity of a translative formula proved recently in Geom. Dedicata 57 (1995), 259--283.     

Orthomodular lattices with rich state spaces

We introduce a new construction technique for orthomodular lattices. In contrast to the preceding constructions, it admits rich spaces of states (= probability measures), i.e., for each pair of incomparable elements a,c there is a state s such that s(a) = 1 > s(c). This allowed a progress in many questions that were open for a long time; among others we prove that there is a continuum of varieties of orthomodular lattices with rich state spaces and solve a problem formulated by R. Mayet in 1985. As a by-product of this research, the uniqueness problem for bounded observables (posed by S. Gudder in 1966) has been solved. As a tool, we introduce also a new construction –identification of atoms in an orthomodular lattice – which may be of separate interest.     

Buffon type problem in the euclidean spaceR 3

Consider a sphere of radiusr whose centre is uniformly distributed inR ³ in the sense that the kinematic measure associated with the centre is that given in Santaló (1976). Consider a lattice of planes whose elementary cell consists of a prism of heighth and with the base an arbitrary triangle of sidesa, b, c. Bosetto (1997) considered the case when the base of the prism is a right-angled triangle, computed the probability that the random sphere cuts at least one of the planes of the lattice and established some independence properties of certin events. Here the same probability is computed for prisms of arbitrary triangular bases and expressed in terms of symmetric expressions. Independence properties and generalization to prisms with arbitrary polygonal bases are also considered.     

The kurzweil construction of an integral in ordered spaces

This paper generalizes the results of papers which deal with the Kurzweil-Henstock construction of an integral in ordered spaces. The definition is given and some limit theorems for the integral of ordered group valued functions defined on a Hausdorff compact topological space T with respect to an ordered group valued measure are proved in this paper.     

“Grandi” lenti in un reticolo di rette

A buffon problem is studied for a “thin lens” in the plane, a convex test body made by the union of two circular segments both less than or equal to a semicircle. The case in which the lens is “small” compared with the distance between the parallel lines of the Buffon lattice has been treated in [4]. The instance investigated in this paper is the one of a “large” lens, i.e. of a lens which can have multiple intersections with the Buffon lattice.

Lavoro eseguito col contributo parziale del M.U.R.S.T.     

The isoperimetric profile of a smooth Riemannian manifold for small volumes

We define a new class of submanifolds called pseudo-bubbles, defined by an equation weaker than constancy of mean curvature. We show that in a neighborhood of each point of a Riemannian manifold, there is a unique family of concentric pseudo-bubbles which contains all the pseudo-bubbles C ^2,α -close to small spheres. This permit us to reduce the isoperimetric problem for small volumes to a variational problem in finite dimension. Work supported by a grant from INDAM “Istituto Nazionale di Alta Matematica Francesco Severi” (Roma).