Abstract:
A quadratic point on a surface in RP3 is a point at which the surface can be approximated by a quadric abnormally well (up to order 3). We conjecture that the least number of quadratic points on a generic compact nondegenerate hyperbolic surface is 8; the relation between this and the classic Carathéodory conjecture is similar to the relation between the six-vertex and the four-vertex theorems on plane curves. Examples of quartic perturbations of the standard hyperboloid confirm our conjecture. Our main result is a linearization and reformulation of the problem in the framework of the 2-dimensional Sturm theory; we also define a signature of a quadratic point and calculate local normal forms recovering and generalizing the Tresse–Wilczynski theorem.
Citation:
S. L. Tabachnikov, V. Yu. Ovsienko, “Hyperbolic Carathéodory Conjecture”, Analysis and singularities. Part 1, Collected papers. Dedicated to academician Vladimir Igorevich Arnold on the occasion of his 70th birthday, Trudy Mat. Inst. Steklova, 258, Nauka, MAIK «Nauka/Inteperiodika», M., 2007, 185–200; Proc. Steklov Inst. Math., 258 (2007), 178–193