Sturm’s famous theorem provides an elegant algorithm to count and locate the real roots of any given real polynomial. It is less widely known that Cauchy extended this to an algebraic method to count and locate the complex roots of any given complex polynomial. We give an algebraic proof of this beautiful result, starting from the mere axioms of the fields R and C, without any further appeal to...

In this note, we establish a connection between the dynamical degree, or algebraic entropy of a certain class of polynomial automorphisms of R3, and the maximum topological entropy of the action when restricted to compact invariant subvarieties. Indeed, when there is no cancellation of leading terms in the successive iterates of the polynomial automorphism, the two quantities are equal. In gene...

Abstract Let f :=(f1, . . . , fn) be a sparse random polynomial system. This means that each f i has fixed support (list of possibly non-zero coefficients) and each coefficient has a Gaussian probability distribution of arbitrary variance. We express the expected number of roots of f inside a region U as the integral over U of a certain mixed volume form. When U = (C∗)n, the classical mixed vol...

Several cryptographic methods have been developed based on the difficulty to determine the set of solutions of a polynomial system over a given field. We build a polynomial ideal whose algebraic set is related to the set of isomorphisms between two graphs. The problem isomorphism, posed in the context of Graph Theory, has been extensively used in zero knowledge authentication protocols. Thus, a...

in this study, the problem of determining an optimal trajectory of a nonlinear injection into orbit problem with minimum time was investigated. the method was based on orthogonal polynomial approximation. this method consists of reducing the optimal control problem to a system of algebraic equations by expanding the state and control vector as chebyshev or legendre polynomials with undetermined...

A plane algebraic curve can be represented as the zero-set of a polynomial in two or if one takes homogenous coordinates: three variables. The coefficients of the polynomial determine the curve uniquely. Thus features of the curve, like for instance rotation symmetry, must find their correspondence in the algebraic structure of the coefficients of the polynomial. In this article we will investi...