Computing points in connected components defined by a real inequation: algorithms, complexity and implementations, Part I
JΓ©rΓ©my Berthomieu, Edern Gillot, Mohab Safey El Din
arxiv.org/abs/2605.18110 [ππ.ππ² ππππ.π°πΆ]
ALT We consider the problem of computing sample points in each connected component of a semi-algebraic set defined by the non-vanishing or the positivity of an n-variate polynomial of degree d, with rational coefficients of bit size bounded by Ο. Such a problem is a basic routine in effective real algebraic geometry, used in higher-level algorithms for solving polynomial systems over the reals and finds many applications in sciences. We design a probabilistic algorithm for solving this problem, which is based on reductions to different routines for solving zero-dimensional polynomial systems. It assumes that the input polynomial satisfies sufficiently generic properties (namely, smoothness of its defining hypersurface). This is done through the computations of critical points of well-chosen maps to capture the connected components of the semi-algebraic set under study. We derive a bit complexity estimate for the cost of this algorithm, which is, in terms of the BΓ©zout bound d(d -1)βΏβ»ΒΉ, ess