Planar graph canonization is known to be hard for L this directly follows from L-hardness of tree-canonization [Lin92]. We give a log-space algorithm for planar graph canonization. This gives completeness for log-space under AC many-one reductions and improves the previously known upper bound of AC [MR91]. A planar graph can be decomposed into biconnected components. We give a log-space procedu...

Many intractable computational problems on graphs admit tractable algorithms when applied to trees or forests. Tree decomposition extracts a tree structure from a graph by grouping nodes into bags, where each bag corresponds to a single node in of the tree. The corresponding operation on hypergraphs is that of a generalized hypertree decomposition [10], which entails a tree decomposition of the...

The Semantic Web facilitates integrating partial knowledge and finding evidence for hypothesis from web knowledge sources. However, the appropriate level of granularity for tracking provenance of RDF graph remains in debate. RDF document is too coarse since it could contain irrelevant information. RDF triple will fail when two triples share the same blank node. Therefore, this paper investigate...