Izvestiya of Saratov University.
ISSN 1816-9791 (Print)
ISSN 2541-9005 (Online)

convex body

On Functional Stability of the Solution for the Problem of Convex Body Best Approximating by a Ball with Fixed Radius

A finite-dimensional problem of finding a uniform estimate (approximation in the Hausdorff metric) of a convex body by a fixed-radius ball in an arbitrary norm is considered. It is known that this problem can be reduced to a linear programming problem in the case, when the convex body and the norm ball are polytops. Therefore, we prove the functional stability of the optimal value of the objective function with respect to accuracy of the given convex body and accuracy of the unit ball for the norm used. The stability rating is derived.

On an Inner Estimate of a Convex Body by the Lebesgue Set of Convex Differentiable Function

A finite-dimentional problem of embedding the largest by the inclusion of lower Lebesgue set of given convex function f(x) in a given convex body D ⊂ R p is considered. This problem is the generalization of the problem of inscribed ball (function f(x) is some norm, and the Lebesgue sets are the corresponding balls). The function f(x) must be differentiable on R p possibly expending the point 0 p and 0 p is the uniqueness point of minimum.