[anigbrowl]

Well, given my erroneous thinking about lines vs. curves (something you sometimes see exploited in other puzzles), when I say 'defeatable' I mean from the point of view of the warden, who would be seeking to minimize the prisoners' chances of success. You know, 'mwuhhahaha! I never said they were in a straight line' or indeed 'mwuhahaha, I never said we were in Euclidean space!'.