Query-preserving watermarking of relational databases and XML documents
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Polynomial-TimeMaximisation Classes: Syntactic Hierarchy
Fundamenta Informaticae - Workshop on Combinatorial Algorithms
Query-preserving watermarking of relational databases and Xml documents
ACM Transactions on Database Systems (TODS)
Kernelization for maximum leaf spanning tree with positive vertex weights
CIAC'10 Proceedings of the 7th international conference on Algorithms and Complexity
Polynomial-TimeMaximisation Classes: Syntactic Hierarchy
Fundamenta Informaticae - Workshop on Combinatorial Algorithms
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Extending a well-known property of NP optimization problems in which the value of the optimum is guaranteed to be polynomially bounded in the length of the input, it is observed that, by attaching weights to tuples over the domain of the input, all NP optimization problems admit a logical characterization. It is shown that any NP optimization problem can be stated as a problem in which the constraint conditions can be expressed by a $\Pi_2$ first-order formula. The paper analyzes the weighted analogue of all syntactically defined classes of optimization problems that are known to have good approximation properties in the nonweighted case. Dramatic changes occur when negative weights are allowed.