Network-based heuristics for constraint-satisfaction problems
Artificial Intelligence
Hypertree decompositions and tractable queries
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
ACM Transactions on Information Systems (TOIS)
Holistic twig joins: optimal XML pattern matching
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Query evaluation via tree-decompositions
Journal of the ACM (JACM)
Conditional XPath, the first order complete XPath dialect
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Conjunctive queries over trees
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
The complexity of XPath query evaluation and XML typing
Journal of the ACM (JACM)
On the complexity of nonrecursive XQuery and functional query languages on complex values
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On boosting holism in XML twig pattern matching using structural indexing techniques
Proceedings of the 2005 ACM SIGMOD international conference on Management of data
From tree patterns to generalized tree patterns: on efficient evaluation of XQuery
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Beyond XML and RDF: the versatile web query language xcerpt
Proceedings of the 15th international conference on World Wide Web
Evaluation of datalog extended with an XPath predicate
Proceedings of the 9th annual ACM international workshop on Web information and data management
Using a relational processor and an XPath processor to evaluate joint queries
DataX '08 Proceedings of the 2008 EDBT workshop on Database technologies for handling XML information on the web
Evaluating very large datalog queries on social networks
Proceedings of the 12th International Conference on Extending Database Technology: Advances in Database Technology
Four lessons in versatility or how query languages adapt to the web
Semantic techniques for the web
Efficient enumeration for conjunctive queries over x-underbar structures
CSL'10/EACSL'10 Proceedings of the 24th international conference/19th annual conference on Computer science logic
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N-ary conjunctive queries, i.e., queries with any number of answer variables, are the formal core of many Web query languages including XSLT, XQuery, SPARQL, and Xcerpt. Despite a considerable body of research on the optimization of such queries over tree-shaped XML data, little attention has been paid so far to efficient access to graph-shaped XML, RDF, or Topic Maps. We propose the first evaluation technique for n-ary conjunctive queries that applies to both tree- and graph-shaped data and retains the same complexity as the best known approaches that are restricted to tree-shaped data only. Furthermore, the approach treats tree and graph-shaped queries uniformly without sacrificing evaluation complexity on the restricted query class. The core of the evaluation technique is based on dynamic programming using a memoization data structure, called "memoization matrix". It can be populated and consumed in different ways. For each of population and consumption, we propose two resp. three algorithms each having their own advantages. The complexity of the algorithms is compared analytically and experimentally.