Abstract
Two special cases of eco-grammar systems are studied, namely the systems with identical agents, called monocultures and the systems with homogeneous environment characterized by a unary alphabet. The generative power of these eco-grammar systems, given by the languages of the environments, is discussed. Introduced special cases restrict the generative power of eco-grammar systems. Hierarchy or incomparability of language classes with respect to the degree of eco-grammar systems, given by the number of the agents, is shown for various cases of eco-grammar systems.