Efficiently computing alignments: using the extended marking equation

Conformance checking is considered to be anything where observed behaviour needs to be related to already modelled behaviour. Fundamental to conformance checking are alignments which provide a precise relation between a sequence of activities observed in an event log and a execution sequence of a model. However, computing alignments is a complex task, both in time and memory, especially when models contain large amounts of parallelism. When computing alignments for Petri nets, (Integer) Linear Programming problems based on the marking equation are typically used to guide the search. Solving such problems is the main driver for the time complexity of alignments. In this paper, we adopt existing work in such a way that (a) the extended marking equation is used rather than the marking equation and (b) the number of linear problems that is solved is kept at a minimum. To do so, we exploit fundamental properties of the Petri nets and we show that we are able to compute optimal alignments for models for which this was previously infeasible. Furthermore, using a large collection of benchmark models, we empirically show that we improve on the state-of-the-art in terms of time and memory complexity.