Abstract. We present a monitoring tool for plan execution in non-deterministic environments, which are described in an action language, based on non-monotonic logic programming. Thanks to it, deviations of concrete executions from expected ones can be detected, and diagnostic explanations in terms of unsuccessful action executions can be obtained. The latter may be exploited for execution recovery, and may help in rectifying an incoherent view of the planning domain. 

Ján Senko