A method for process modeling includes reading a record of executions of a process including at least first and second activities, and identifying in one of the executions in the record respective first and second lifespans of the first and second activities, defined by respective initiating and finish events, such that the initiating event of the second lifespan occurs during the first lifespan. A graphic model of the process is generated, so as to reflect a concurrency of the first and second activities, responsively to occurrence of the initiating event of the second lifespan during the first lifespan.