CPN-Py: A Python-Based Tool for Modeling and Analyzing Colored Petri Nets

Alessandro Berti, Wil M. P. van der Aalst

Abstract: Colored Petri Nets (CPNs) are an established formalism for modeling processes where tokens carry data. Although tools like CPN Tools and CPN IDE excel at CPN-based simulation, they are often separate from modern data science ecosystems. Meanwhile, Python has become the de facto language for process mining, machine learning, and data analytics. In this paper, we introduce CPN-Py, a Python library that faithfully preserves the core concepts of Colored Petri Nets -- including color sets, timed tokens, guard logic, and hierarchical structures -- while providing seamless integration with the Python environment. We discuss its design, highlight its synergy with PM4Py (including stochastic replay, process discovery, and decision mining functionalities), and illustrate how the tool supports state space analysis and hierarchical CPNs. We also outline how CPN-Py accommodates large language models, which can generate or refine CPN models through a dedicated JSON-based format.