Zero-nonzero and real-nonreal sign determination

We consider first the zero–nonzero determination problem, which consists in determining the list of zero–nonzero conditions realized by a finite list of polynomials on a finite set Z⊂Ck with C an algebraic closed field. We describe an algorithm to solve the zero–nonzero determination problem and we perform its bit complexity analysis. This algorithm, which is in many ways an adaptation of the methods used to solve the more classical sign determination problem, presents also new ideas which can be used to improve sign determination. Then, we consider the real–nonreal sign determination problem, which deals with both the sign determination and the zero–nonzero determination problem. We describe an algorithm to solve the real–nonreal sign determination problem, we perform its bit complexity analysis and we discuss this problem in a parametric context. Fil: Perrucci, Daniel Roberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemática; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria; Argentina Fil: Roy, Marie Françoise. Universite de Rennes I. Institut de Recherche Mathematique de Rennes; Francia