Organizations increasingly rely on business process analysis to improve operations performance. Process Mining can be exploited to distill models from real process executions recorded in event logs, but existing techniques show some limitations when applied in complex domains, where human actors have high degree of freedom in the execution of activities thus generating highly variable processes instances. The present paper contributes to the research on Process Mining in highly variable domains, focusing on the generation of process instance models (in the form of Instance Graphs) from simple event logs. The novelty of the approach is in the exploitation of filtering Process Discovery techniques coupled with repairing, which allows obtai...