In semantic web technologies a named graph is a collection of RDF (a graph) that is named by a URI. Sewveral named graohs can then be stored as graph–subject–predicate–object tuples in a quadstore. named graohs allows meta-level reasoning such as asking, "can it be determined from graph G whether A is a subclass of B", and also provenance by RDF tuples that descibe the graph.
Used in Chap. 17: pages 272, 273