Suppose intruders are in a dark polygonal room and they can move at a finite but unbounded speed, trying to avoid detection. A boundary 1-searcher can move along the polygon boundary, equipped with a flash light that she can direct in any direction. A polygon is searchable if there is a schedule for the searcher to follow in order to always detect the intruders. We identify three forbidden patterns of a polygon such that a given polygon is searchable by a boundary 1-searcher if and only if it has none of them.
Tsunehiko Kameda, John Z. Zhang, Masafumi Yamashit