Value chain; Object-valued Petri nets; cycle Petri nets; simulation; model validation

A substantial part of the economic theories is based on conversion and exchange process. This process can be described as a value chain, which can be considered as a cyclic model with complex attributes. There is a serious problem how to express resources and their conversions in a complex cyclic model during the simulation and how to identify these converted resources in every step of the simulation. This paper introduces the Object- valued Petri (OV-PN) modification as a new formalism to create a cyclic model of the value chain. According to the modification we had to define a new path and pass of the OV-PN. We also had to determine new properties. Properties are based on the OV-PN and reflect needs of model requirements. A new formalism is verified on a common enterprise value chain.