Parallel rewriting of graphs through the pullback approach

We continue here the development of our description of the pullback approach to graph rewriting-already shown to encompass both the NCE and the double-pushout approach, by describing parallel application of rewriting rules. We show that this new framework provides a genuine deenition of parallel rewriting (parallel application of several rewriting rules at several diierent places in the graph is actually expressed through the application of one single mathematical operation) and even further that a deterministic graph grammar can be described by a single rule which we call P-grammar.