Revisit the Lovász Local Lemma

We provide a sufficient condition for showing that the probability of none of the events A ₁, A ₂,...,A _n occurs is positive. This condition explicitly involves the dependency digraph and the probabilities of the A _i's. Some applications are given.     

On the Secant method for solving nonsmooth equations

In this study we are concerned with the problem of approximating a locally unique solution of an operator equation in Banach space using the Secant method. The differentiability of the operator involved is not assumed. Using a flexible point-based approximation, we provide a local as well as a semilocal convergence analysis for the Secant method. Our results are justified by numerical examples that cannot be handled with earlier works.     

Some generalizations of Ahlfors Lemma

One of the most influential versions of the classical Schwarz–Pick Lemma is probably that of Ahlfors. Pulling back a conformal semimetric on a Riemann surface under any holomorphic map from the open unit disk equipped with a Poincaré metric, the curvature of which is assumed to bound from above the curvature of the Riemann surface, he successfully showed that a conformal semimetric to be compared with the Poincaré metric is obtained. In the present paper, we give a comparison theorem between two conformal semimetrics of variable curvature in the same spirit. Our main theorem is a local one by its nature, but global results can be derived therefrom.     

A note on the short algebraic proof of Farkas' Lemma

The author published ‘A Short Algebraic Proof of the Farkas Lemma’ [SIAM J. Optim. 19 (2008), pp. 234–239]. The author then found, in his opinion, a better exposition of the proof. He would therefore like to publish the new form of the proof in this note.     

Large deviations for estimators of unknown probabilities, with applications in risk theory

We present large deviation results for estimators of unknown probabilities which satisfy a suitable exponential decay condition. These results provide some extensions of the large deviation estimates given in Macci and Petrella (2006). Furthermore we propose a classical approach which is different from the one presented in Ganesh et al. (1998) and we cannot say that the Bayesian approach is more conservative as in that paper.     

关于集值条件期望的一些极限结果

给出随机集列关于单调战σ-域族的集值条件期望序列弱上(下)极限收敛意义下的Fatou引理以及在弱收敛,Kuratowski-Mosco收敛意义下的控制收敛定理.     

On the asymptotic distribution of a unit root test against ESTAR alternatives

We derive the null distribution of the nonlinear unit root test proposed in Kapetanios et al. [Kapetanios, G., Shin, Y., Snell, A., 2003. Testing for a unit root in the nonlinear STAR framework. Journal of Econometrics 112, 359-379] when nonzero means or both means and deterministic trends are accounted for. Some discrepancies to claims in Kapetanios et al. are discussed.     

Some geometric applications of the beta distribution

Let be the angle between a line and a random k-space in Euclidean n-space R ⁿ. Then the random variable cos² has the beta distribution. This result is applied to show (1) in R ⁿthere are exponentially many (in n) lines going through the origin so that any two of them are nearly perpendicular, (2) any N-point set of diameter d in R ⁿlies between two parallel hyperplanes distance 2d{(log N)/(n-1)}^1/2 apart and (3) an improved version of a lemma of Johnson and Lindenstrauss (1984, Contemp. Math., 26, 189–206). A simple estimate of the area of a spherical cap, and an area-formula for a neighborhood of a great circle on a sphere are also given.     

高阶Morse芽的存在性

本文研究了多元C∞函数芽环中高阶Morse芽的存在性问题.利用由函数芽的偏导数生成的理想和C∞函数芽上的右等价关系,获得了在C∞函数芽环中,除了二元C∞函数芽环中有三阶和四阶的Morse芽以后,不再存在其它的Morse芽.以致在三元以上的C∞函数芽环中Morse引理不能推广到较高阶的情形.