Using μ-bases to reduce the degree in the computation of projective equivalences between rational curves in n-space

We study how projective equivalences between rational curves in Rn are transferred to the elements of smallest degree of the μ-bases of the curves. We show how to compute these elements of smallest degree without computing the whole μ-basis, and prove some results on the degrees of μ-bases of curves in Rn. As a result, we provide a way to reduce the cost of computing the projective equivalences between rational curves in Rn by replacing the given curves for the curves represented by the elements of smallest degree of the μ-bases of the curves, which have a much smaller degree compared to the original degree of the curves.Agencia Estatal de Investigació

Affine equivalences of surfaces of translation and minimal surfaces, and applications to symmetry detection and design

We introduce a characterization for affine equivalence of two surfaces of translation defined by either rational or meromorphic generators. In turn, this induces a similar characterization for minimal surfaces. In the rational case, our results provide algorithms for detecting affine equivalence of these surfaces, and therefore, in particular, the symmetries of a surface of translation or a minimal surface of the considered types. Additionally, we apply our results to designing surfaces of translation and minimal surfaces with symmetries, and to computing the symmetries of the higher-order Enneper surfaces.publishedVersio

Computing projective equivalences of special algebraic varieties

This paper is devoted to the investigation of selected situations when computing projective (and other) equivalences of algebraic varieties can be efficiently solved via finding projective equivalences of finite sets of points on the projective line. In particular, we design a method that finds for two algebraic varieties X, Y from special classes an associated set of automorphisms of the projective line (the so called good candidate set) consisting of suitable candidates for the subsequent construction of possible mappings X -> Y. The functionality of the designed approach is presented for computing pro- jective equivalences of rational curves, determining projective equivalences of rational ruled surfaces, detecting affine transformations between planar algebraic curves, and computing similarities between two implicitly given algebraic surfaces. When possible, symmetries of given shapes are also discussed as special cases