Fourth generation structured query languages can be used to aggregate scalars associated with the nodes of a directed acyclic graph. Node tables, edge tables, and a transitive closure table can be used to perform these aggregate operations. The invention provides a declarative methodolgy for calculating...http://www.google.de/patents/US6006233?utm_source=gb-gplus-sharePatent US6006233 - Method for aggregation of a graph using fourth generation structured query language (SQL)
