  We consider the problem of efficient patrolling strategy adaptation in a
changing environment where the topology of Defender's moves and the importance
of guarded targets change unpredictably. The Defender must instantly switch to
a new strategy optimized for the new environment, not disrupting the ongoing
patrolling task, and the new strategy must be computed promptly under all
circumstances. Since strategy switching may cause unintended security risks
compromising the achieved protection, our solution includes mechanisms for
detecting and mitigating this problem. The efficiency of our framework is
evaluated experimentally.
