Rafael Murrieta-Cid Raul Monroy Seth Hutchinson Jean-Paul Laumond A Complexity result for the pursuit-evasion game of maintaining visibility of a moving evader. 2657-2664 2008 ICRA http://dx.doi.org/10.1109/ROBOT.2008.4543613 conf/icra/2008 db/conf/icra/icra2008.html#Murrieta-CidMHL08