A Graph-Based Square Grids Generating Mechanism

Graph grammar has been employed as a tool to express formal logic of graph structures. Among different mechanisms, pullback categorical grammars have been proved to be intrinsically context-free. We will show in this paper that this kind of graph grammar can be used for modeling a mechanism which generates square grids and only square grids. With semantics this mechanism will be a good candidate for studying semantic web, or semantic grid.