Minimal Tetrahedralizations of a Class of Polyhedra

Given a simple polyhedron P in the three dimensional Euclidean space, different tetrahedralizations of P may contain different numbers of tetrahedra. The minimal tetrahedralization is a tetrahedralization with the minimum number of tetrahedra. In this paper, we present some properties of the graph of polyhedra. Then we identify a class of polyhedra and show that this kind of polyhedra can be minimally tetrahedralized in O(n ²) time.     

香港新城规划建设对天津的启示

香港作为国际化大都市,人口众多,土地资源十分紧张。为了应对人口迅速增长对香港本岛和九龙市区带来的各种压力,香港从20世纪70年代就开始规划建设新市镇,也就是新城。新城在香港规划史上占有重要的位置,在香港整体发展中也扮演了积极的角色,很多方面值得我们借鉴。     

浅谈求解逆矩阵的方法

在线性代数的教学中,逆矩阵是一个非常重要的内容。本文介绍了利用初等变换的方法来求逆矩阵,运用分块矩阵的思想来求解、证明逆矩阵的方法,对于培养学生思维品质和提高学生解题能力,会起到积极作用。     

Fast searching games on graphs

Given a graph, suppose that intruders hide on vertices or along edges of the graph. The fast searching problem is to find the minimum number of searchers required to capture all the intruders satisfying the constraint that every edge is traversed exactly once and searchers are not allowed to jump. In this paper, we prove lower bounds on the fast search number. We present a linear time algorithm to compute the fast search number of Halin graphs and their extensions. We present a quadratic time algorithm to compute the fast search number of cubic graphs.     

Lower bounds for positive semidefinite zero forcing and their applications

The positive semidefinite zero forcing number of a graph is a parameter that is important in the study of minimum rank problems. In this paper, we focus on the algorithmic aspects of computing this parameter. We prove that it is NP-complete to find the positive semidefinite zero forcing number of a given graph, and this problem remains NP-complete even for graphs with maximum vertex degree 7. We present a linear time algorithm for computing the positive semidefinite zero forcing number of generalized series–parallel graphs. We introduce the constrained tree cover number and apply it to improve lower bounds for positive semidefinite zero forcing. We also give formulas for the constrained tree cover number and the tree cover number on graphs with special structures.     

A Study for Missing Values in PINAR(1)T Processes

In this paper, we propose several approaches to estimate the parameters of the periodic first-order integer-valued autoregressive process with period T (PINAR(1)_T) in the presence of missing data. By using incomplete data, we propose two approaches that are based on the conditional expectation and conditional likelihood to estimate the parameters of interest. Then we study three kinds of imputation methods for the missing data. The performances of these approaches are compared via simulations.     

Standard directed search strategies and their applications

Given a digraph that contains an intruder hiding on vertices or along edges, a directed searching problem is to find the minimum number of searchers required to capture the intruder. In this paper, we propose the standard directed search strategies, which can simplify arguments in proving search numbers, lower bounds, and relationships between search models. Using these strategies, we characterize k-directed-searchable graphs when k≤3. We also use standard directed search strategies to investigate the searching problems on oriented grids. We give tight lower and upper bounds for the directed search number of general oriented grids. Finally, we show how to compute the directed search number of a Manhattan grid. Yang’s research was supported in part by NSERC and MITACS.     

"互联网+"视阙下生物学专业融入"双创"教育的策略与实践 ——以韶关学院为例

在当前"互联网+"形势下,专业教育融入"双创"教育是对传统教育理念和专业教育模式的变革,该模式促使学生在创新创业实践活动中将专业理论知识实用化.为了深入探讨应用型本科院校生物学专业教育与"双创"教育的有机融合机制,通过剖析专业教育融入"双创"教育的途径与模式,借鉴各类高校创新创业教育的成功经验,并结合韶关学院实际情况,探索"互联网+"视阙下创新创业教育与生物学专业教育融合策略,以期为构建专业教育兼容创新创业教育教学模式、增强生物学专业学生的综合素养、提升应用型本科院校办学特色和教育水平提供理论基础.     

Strong-mixed searching and pathwidth

In this paper, we propose a new search model, called strong-mixed search, which is a generalization of the mixed search. We show that the strong-mixed search number of a graph equals the pathwidth of the graph. We also describe relationships between the strong-mixed search number and other search numbers.Research was supported in part by NSERC and MITACS.