Before revision:  This is also known as the conflict-free chromatic guarding problem with vertex guards (which is quite different from point guards considered in some other papers).We study the problem in two scenarios of a set of viewers. In the first one, we assume that the viewers are all points of the polygon  .
After revision:  This is also known as the conflict-free chromatic guarding problem with vertex guards , and is motivated, e.g., by the problem of radio frequency assignment to sensors placed at the polygon vertices. We first study the scenario in which viewers can be all points of the polygon .