Plan Recognition as Probabilistic Trace Alignment

Plan Recognition is the task of identifying the goals and plans of an agent by observing its behavior within the environment. The problem has been extensively studied in the context of planning, in particular bringing forward stochastic techniques dealing with probability distributions over the possible agent goals, under the assumption that observations are reliable. More recently, a connection between this problem and process mining techniques has been established, paving the way towards the application of alignment-based conformance checking techniques from process mining to tackle plan recognition problems in a setting where observations may be faulty. In this work, we reconcile these two lines of research in a unified framework that deals at once with uncertainty over the goals and the faithfulness of observations. Instead of using ad-hoc techniques to solve this problem, we cast it as a probabilistic trace alignment problem, trading off between the similarity of observations and plans, and the likelihood that the agent is performing those plans. We assess the effectiveness of our approach by conducting a comparative experimental evaluation on state-of-the-art benchmarks.