Cycloids are particular Petri nets for modelling processes of actions and events, belonging to the fundaments of Petri's general systems theory. Defined by four parameters they provide an algebraic formalism to describe strongly synchronized sequential processes. To further investigate their structure, reduction systems of cycloids are defined in the style of rewriting systems and properties of reduced cycloids are proved. In particular the recovering of cycloid parameters from their Petri net structure is derived.

翻译：环面是一类特殊的Petri网，用于建模动作与事件的过程，属于Petri一般系统理论的基石。通过四个参数定义，环面提供了描述强同步顺序过程的代数形式体系。为深入研究其结构，本文以重写系统风格定义了环面约化系统，并证明了约化环面的性质。特别地，推导了从Petri网结构恢复环面参数的方法。