Access structure for generalized transitive closure queries

This paper presents an access structure to accelerate the processing of generalized transitive closure queries. For an acyclic graph, the access structure consists of source-destination pairs arranged in a topologically sorted order. For a cyclic graph, entries in the structure are `approximately' topologically sorted. We present a breadth-first algorithm for creating such a structure, show how it can be used to process queries, and describe incremental techniques for maintaining it.