Some readers have requested clarification about the assumptions on the capabilities of searchlights. In particular, about whether boundary searchlights can rotate past their adjacent walls. As stated in the literature, a searchlight is a rotatable beam sensor which ``cannot penetrate the environment boundary''. It is intended here that the environment boundary only restricts a searchlight's ability to sense, not its rotation. All searchlights, even those located on the environment boundary, are free to rotate 360 degrees. A beam may thus have length zero if its respective searchlight is aiming into a wall, but it is free to aim there. This assumption on searchlight rotation capabilities is the most natural because it means that there is no discontinuity in a searchlight's rotation range as its location approaches and then goes onto the environment boundary. There also are important computational implications of the assumption, e.g., to guarantee a rotation monotone schedule exists as in Conjecture 3.1 of the IJCGA paper A Complete Algorithm for Searchlight Scheduling (Chapter 3, Conjecture 3.1 of the dissertation Visibility Problems for Sensor Networks and Unmanned Air Vehicles).
In the GNC paper Sampling-Based Roadmap Methods for a Visual Reconnaissance UAV and Chapter 5.3 of the PhD dissertation Visibility Problems for Sensor Networks and Unmanned Air Vehicles, the convergence theorems require a general position assumption. We provide a detailed description of the general position assumption in Section IV.A of this JGCD article.