Real zeros of the zero-dimensional parametric piecewise algebraic variety  

作　　者：LAI YiSheng WANG RenHong WU JinMing 

机构地区：[1]Department of Information and Computer Science,Zhejiang Gongshang University,Hangzhou 310018,China [2]Institute of Mathematical Sciences,Dalian University of Technology,Dalian 116024,China

出　　处：《Science China Mathematics》2009年第4期817-832,共16页中国科学：数学（英文版）

基　　金：supported by National Natural Science Foundation of China (Grant Nos. 10271022, 60373093,60533060);the Natural Science Foundation of Zhejiang Province (Grant No. Y7080068);the Foundation of Department of Education of Zhejiang Province (Grant Nos. 20070628 and Y200802999)

摘　　要：The piecewise algebraic variety is the set of all common zeros of multivariate splines. We show that solving a parametric piecewise algebraic variety amounts to solve a finite number of parametric polynomial systems containing strict inequalities. With the regular decomposition of semi-algebraic systems and the partial cylindrical algebraic decomposition method, we give a method to compute the supremum of the number of torsion-free real zeros of a given zero-dimensional parametric piecewise algebraic variety, and to get distributions of the number of real zeros in every n-dimensional cell when the number reaches the supremum. This method also produces corresponding necessary and sufficient conditions for reaching the supremum and its distributions. We also present an algorithm to produce a necessary and sufficient condition for a given zero-dimensional parametric piecewise algebraic variety to have a given number of distinct torsion-free real zeros in every n-cell in the n-complex.The piecewise algebraic variety is the set of all common zeros of multivariate splines. We show that solving a parametric piecewise algebraic variety amounts to solve a finite number of parametric polynomial systems containing strict inequalities. With the regular decomposition of semi- algebraic systems and the partial cylindrical algebraic decomposition method, we give a method to compute the supremum of the number of torsion-free real zeros of a given zero-dimensional parametric piecewise algebraic variety, and to get distributions of the number of real zeros in every n-dimensional cell when the number reaches the supremum. This method also produces corresponding necessary and suffcient conditions for reaching the supremum and its distributions. We also present an algorithm to produce a necessary and suffcient condition for a given zero-dimensional parametric piecewise algebraic variety to have a given number of distinct torsion-free real zeros in every n-cell in the n-complex.

关 键 词：piecewise algebraic variety partial cylindrical algebraic decomposition number of real zeros 14M15 14Q10 41A15 41A46 65D07 65D10 

分 类 号：O187[理学—数学]