On a Dualization of Graphical Gaussian Models: A Correction Note

Abstract.  We correct two proofs concerning Markov properties for graphs representing marginal independence relations.     

Markov Properties for Acyclic Directed Mixed Graphs

We consider acyclic directed mixed graphs, in which directed edges ( x → y ) and bi-directed edges ( x ↔ y ) may occur. A simple extension of Pearl's d -separation criterion, called m -separation, is applied to these graphs. We introduce a local Markov property which is equivalent to the global property resulting from the m -separation criterion for arbitrary distributions.     

A Unified Approach to the Characterization of Equivalence Classes of DAGs, Chain Graphs with no Flags and Chain Graphs

Abstract.  A Markov property associates a set of conditional independencies to a graph. Two alternative Markov properties are available for chain graphs (CGs), the Lauritzen–Wermuth–Frydenberg (LWF) and the Andersson–Madigan– Perlman (AMP) Markov properties, which are different in general but coincide for the subclass of CGs with no flags . Markov equivalence induces a partition of the class of CGs into equivalence classes and every equivalence class contains a, possibly empty, subclass of CGs with no flags itself containing a, possibly empty, subclass of directed acyclic graphs (DAGs). LWF-Markov equivalence classes of CGs can be naturally characterized by means of the so-called largest CGs , whereas a graphical characterization of equivalence classes of DAGs is provided by the essential graphs . In this paper, we show the existence of largest CGs with no flags that provide a natural characterization of equivalence classes of CGs of this kind, with respect to both the LWF- and the AMP-Markov properties. We propose a procedure for the construction of the largest CGs, the largest CGs with no flags and the essential graphs, thereby providing a unified approach to the problem. As by-products we obtain a characterization of graphs that are largest CGs with no flags and an alternative characterization of graphs which are largest CGs. Furthermore, a known characterization of the essential graphs is shown to be a special case of our more general framework. The three graphical characterizations have a common structure: they use two versions of a locally verifiable graphical rule. Moreover, in case of DAGs, an immediate comparison of three characterizing graphs is possible.     

论非专利技术的转让

非专利技术在技术转让中占有越来越重要的地位,其表现形式的多样化、内容的广泛性以及不受时间、空间限制的特点都使其较之专利技术更为有实用价值。非专利技术是以占有人采取保密的形式而形成事实上的独占资产。因而,在技术转让中,合同成为其唯一获得法律保护的途径。本文从非专利技术的产权确定、价格形成的依据以及非专利技术的保密等方面作了论述,说明非专利技术存在的价值以及在转让中应注意的问题。     

On a Class of Nonlinear AR(P) Models with Nonlinear ARCH Errors

This paper studies general sufficient conditions for the geometric ergodicity and the existence of moments for a class of nonlinear autoregressive models with nonlinear ARCH errors. Applications of these conditions to various well-known nonlinear time series models yield specific sufficient conditions, many of which are new or generalizations of existing conditions.     

Penalized inverse probability weighted estimators for weighted rank regression with missing covariates

Abstract

In this article, we study the variable selection and estimation for linear regression models with missing covariates. The proposed estimation method is almost as efficient as the popular least-squares-based estimation method for normal random errors and empirically shown to be much more efficient and robust with respect to heavy tailed errors or outliers in the responses and covariates. To achieve sparsity, a variable selection procedure based on SCAD is proposed to conduct estimation and variable selection simultaneously. The procedure is shown to possess the oracle property. To deal with the covariates missing, we consider the inverse probability weighted estimators for the linear model when the selection probability is known or unknown. It is shown that the estimator by using estimated selection probability has a smaller asymptotic variance than that with true selection probability, thus is more efficient. Therefore, the important Horvitz-Thompson property is verified for penalized rank estimator with the covariates missing in the linear model. Some numerical examples are provided to demonstrate the performance of the estimators.     

Two Statistics for Unconditional Exact Tests in Matched-Pairs Design

Abstract

In a recent article Hsueh et al. (Hsueh, H.-M., Liu, J.-P., Chen, J. J. (2001 Hsueh, H.-M., Liu, J.-P. and Chen, J. J. 2001. Unconditional exact tests for equivalence or noninferiority for paired binary endpoints. Biometrics, 57: 478–483. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Unconditional exact tests for equivalence or noninferiority for paired binary endpoints. Biometrics 57:478–483.) considered unconditional exact tests for paired binary endpoints. They suggested two statistics one of which is based on the restricted maximum-likelihood estimator. Properties of these statistics and the related tests are treated in this article.     

论科技成果管理过程中的知识产权问题

人类社会已经进入了一个新的世纪,大量的科技成果随着科技的迅猛发展而不断问世,知识产权也随之产生并出现争议。本文阐述了科技成果管理过程中产生知识产权争议的原因及其所采取的对策。     

房产税扩围改革相关问题的思考简

目前地方政府基于国务院授权而获得的房产税改革权限的合法性尚有待商榷,推进房产税改革更优的方案应当是由国务院在充分调研、广泛征求意见的基础上修改《房产税暂行条例》。并且,社会各界将房产税功能定位为调控房价、增加财政收入既不合理也不现实,房产税应以完善我国房地产税收体系、促进房地产市场良性发展、调节贫富差距为己任。基于此种目标定位,笔者从征税范围、计税依据、税率、税收用途等方面对房产税改革提出了若干建议。     

物业管理企业经营发展刍议

近 2 0年来 ,我国的物业管理经历了从起步到兴旺的发展阶段。这里针对当前物业管理企业经营的大趋势做了较深入的剖析 ,认为随着买方市场的形成及加入WTO后市场格局的变化 ,我国的物业管理企业正面临着何去何从的艰难抉择 ,对此 ,物业管理企业的经营模式应从“设施保障型”向“服务经营型”转变 ,经营理念应从“物本”向“人本”转变 ,经营渠道应由“单一”向“多元化”转变。