An improved Krasnosel'skij type theorem for orthogonal polygons which are starshaped via staircase paths (Q1339780)

Let \(S\) be a simply connected orthogonal polygon in \(\mathbb{R}^ 2\), and let \(T \subset S\). If every two points of \(T\) are visible via staircase paths from a common point of \(S\), then every three points of \(S\) are visible via staircase paths from some common point of \(S\). Together with the result in a companion paper [see the paper above, the author, ibid., 22- 30 (1994)] it follows that all points of \(S\) are visible from a common point in \(S\).