A spanning tree transitive closure algorithm

The authors present a transitive closure algorithm that maintains a spanning tree of successors for each node rather than a simple successor list. This spanning tree structure promotes sharing of information across multiple nodes and leads to more efficient algorithms. An effective relational implementation of the spanning tree storage structure is suggested, and it is shown how blocking can be applied to reduce the input/output cost of the algorithm. The algorithm can handle path problems also. Analytical and experimental evidence is presented that demonstrates the utility of the algorithm, especially in a graph with many alternate paths between the nodes. The spanning tree storage structure can be compressed and updated incrementally in response to changes in the underlying graph