  A model of a discrete pregeometry on a microscopic scale is introduced. This
model is a finite network of finite elementary processes. The mathematical
description is a d-graph that is a generalization of a graph. This is the
particular case of a causal set. The aim of this study is to construct the
particles as emergent structures. The particles in this model must be cyclic
processes. The general dynamics and several examples are given. A simple
dynamics generates a hierarchy of cyclic processes. An algebraic representation
of this dynamics is given. It is based on the algebra of creation and
destruction operators. Loops are described by bosonic operators and causal
connections are described by fermionic operators.
