On the power of permitting features in cooperating context-free array grammar systems

Among many grammar models for picture description, cooperating context-free distributed array grammar systems utilize the mechanism of cooperation between component array grammars. Here, we endow these grammar systems with the feature of permitting symbols, and examine the generative capacity of the resulting permitting cooperating context-free distributed array grammar systems with certain other kinds of isometric and non-isometric array grammars. An advantage is that the number of components is reduced when this permitting feature is used in a cooperating context-free distributed array grammar system.