====== Extent ======

A special feature of the graph management is the manipulation of [[https://javadoc.grogra.de/graph/de/grogra/graph/impl/Extent.html|extents]]. For each used node class in the graph, there exists an Extent which collects all nodes of this class and also has a link to the extent of its superclass and to the extents of its subclasses. This feature is currently used within the RGG plug-in for a fast processing of queries which specify node type patterns like in the rule ''F(x) %%==>%% F(2*x);''. Instead of having to scan the whole graph for nodes of class F, the corresponding extent is used together with its sub-extents to directly iterate over all nodes of class F.

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