ノルム空間における2つの部分集合に対する最良近似ペア問題
The best approximation pair problem relative to two subsets in a normed space
ノルム空間で非凸部分集合も許容する最良近似ペア問題を扱い、解の存在と一意性のための十分条件を提示した理論研究。
著者: Daniel Reem, Yair Censor
分類: math.OC, cs.GR, cs.RO, math.FA, math.MG
原文アブストラクト
In the classical best approximation pair (BAP) problem, one is given two nonempty, closed, convex and disjoint subsets in a finite- or an infinite-dimensional Hilbert space, and the goal is to find a pair of points, each from each subset, which realizes the distance between the subsets. We discuss the problem in more general normed spaces and with possibly non-convex subsets, and focus our attention on the issues of uniqueness and existence of the solution to the problem. As far as we know, these fundamental issues have not received much attention. We present several sufficient geometric conditions for the (at most) uniqueness of a BAP. These conditions are related to the structure and the relative orientation of the boundaries of the subsets and to the norm. We also present many sufficient conditions for the existence of a BAP. Our results significantly extend the horizon of a recent algorithm for solving the BAP problem [Censor, Mansour, Reem, J. Approx. Theory (2024)]. The paper also shows, perhaps for the first time, how wide is the scope of the BAP problem in terms of the scientific communities which are involved in it (frequently independently) and in terms of its applications.