Polyhedral Line Transversals in Space.
A Fuchsian polyhedron in hyperbolic space is a polyhedral surface invariant under the action of a Fuchsian group of isometries (i.e. a group of isometries leaving globally invariant a totally geodesic surface, on which it acts cocompactly). The induced metric on a convex Fuchsian polyhedron is isometric to a hyperbolic metric with conical singularities of positive singular curvature on a compact surface of genus greater than one. We prove that these metrics are actually realised by exactly one convex...
K. Nikodem and the present author proved in [3] a theorem concerning separation by affine functions. Our purpose is to generalize that result for polynomials. As a consequence we obtain two theorems on separation of an n-convex function from an n-concave function by a polynomial of degree at most n and a stability result of Hyers-Ulam type for polynomials.
Článek se zabývá dělením rovinných mnohoúhelníků na konečný počet částí, z nichž lze sestavit jiné, předem zvolené mnohoúhelníky. Úvodní část je věnována historii těchto disekcí a důkazu Wallaceovy–Bolyaiovy–Gerwienovy věty, podle které lze mezi sebou transformovat libovolné dva mnohoúhelníky o stejném obsahu. Hlavním tématem článku je tzv. Dudeneyho přívěsek, tj. rozdělení rovnostranného trojúhelníku na čtyři části, z nichž lze složit čtverec. Dudeneyho konstrukce je i po sto letech od svého objevu...
At universities focused on economy, Operation Research topics are usually included in the study plan, including solving of Linear Programming problems. A universal tool for their algebraic solution is (numerically difficult) Simplex Algorithm, for which it is necessary to know at least the fundamental of Matrix Algebra. To illustrate this method of solving LP problems and to discuss all types of results, it seems to be very convenient to include a chapter about graphic solutions to LP problems....
On donne un développement asymptotique du profil iso pé ri mé tri que de muni d'une métrique riemannienne périodique, et des conséquences pour le problème de la forme d'équilibre des cristaux.