Positioned eco-grammar systems (PEG systems, for short) were introduced in our previous papers. In this paper we engage in a new field of research, the hierarchy of PEG systems, namely in the hierarchy of the PEG systems according to the number of agents presented in the environment and according to the number of types of agents in the system.
In this paper we extend our results given in [5] where we compared PEG systems with pure regulated context-free grammars (see [3]). We will show that the family of languages generated by the pure grammars of type 0 is a proper subclass of the family of languages generated by positioned eco-grammar systems. We present a way how to coordinate parallel behavior of agents with one-sided context in a PEG system in order to simulate the derivation step in a pure grammar of type 0 determined by a single rule which replaces an arbitrarily long string by another one. Related results concerning PEG systems and pure languages can be found in [6].
In this paper we follow our previous research in the field of positioned agents in the eco-grammar systems and pure grammars. We extend model of the positioned eco-grammar systems by boundary markers and we introduce bordered positioned eco-grammar systems (BPEG systems, for short) and that way we show one of the possible answers to the question stated in \cite{jou}. Namely we compare generative power of the BPEG systems with three types of pure regulated grammars with appearance checking.