Conjunctive Queries over DAGs
We address the complexity of evaluating conjunctive queries over labeled directed acyclic graphs (DAGs). DAG-structured data and queries over such data occur in many contexts, such as ontologies for the Semantic Web and Complex Event Processing. The relations representing the DAG are binary axis relations, mostly adopted from XPath, and unary label relations. The relations definitions are generalized for the DAG case. We prove that all polynomial time results of , except one, become NP-Complete over DAGs.
KeywordsResource Description Framework Conjunctive Query Multiple Label XPath Query Complex Event Processing
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