Showing papers in "Journal of Computer and System Sciences in 2003"

TL;DR: Two constructions of k-dimensional Euclidean embeddings with the property that all elements of the projection matrix belong in {-1, 0, +1 } are given.

TL;DR: An elegant and remarkably simple algorithm ("the threshold algorithm", or TA) is analyzed that is optimal in a much stronger sense than FA, and is essentially optimal, not just for some monotone aggregation functions, but for all of them, and not just in a high-probability worst-case sense, but over every database.

TL;DR: In this article, the degradation in network performance caused by the selfish behavior of noncooperative network users is studied. And the authors consider a model of selfish routing in which the latency experienced by network tr...

TL;DR: An efficient indexing scheme to answer approximate nearest-neighbor queries among moving points, and a tradeoff between the query time and the number of times the index needs to be updated as the points move is obtained.

TL;DR: The main result of the paper is that typechecking for k-pebble transducers is decidable, and therefore, typechecking can be performed for a broad range of XML transformation languages, including XML-QL and a fragment of XSLT.

TL;DR: It is shown that the fixed alphabet shortest common supersequence (SCS) and thefixed alphabet longest common subsequence (LCS) problems parameterized in the number of strings are W[1]-hard, this rules out the existence of algorithms with time complexity of O(f(k)nα) for those problems.

TL;DR: It is shown that in directed networks, for any e>0, EDP is NP-hard to approximate within m1/2-e even in undirected networks, and design simple approximation algorithms that achieve essentially matching approximation guarantees for some generalizations of EDP.

TL;DR: This paper extends XML DTDs with several classes of integrity constraints and investigates the complexity of reasoning about these constraints and establishes complexity and axiomatization results for the (finite) implication problems associated with these constraints.

TL;DR: It is demonstrated that Max-SNP-hard optimization problems do not admit subexponential-time parameterized algorithms and the results are applied to show evidence for the non-existence of O(2o(√k)p(n))-time parameters for a number of other important problems.

TL;DR: The Robber and Marshals game is defined, and it is proved that a hypergraph H has hypertree width at most k if and only if k marshals have a winning strategy on H, allowing them to trap a robber who moves along the hyperedges.

TL;DR: In this article, it was shown that unless P = NP, there is no polynomial time approximation scheme for finding a member in the class that approximately maximizes the agreement with a given training sample.

TL;DR: It is proved that the class of languages having quantum multi-prover interactive proof systems is necessarily contained in NEXP, under the assumption that provers are allowed to share at most polynomially many prior-entangled qubits.

TL;DR: The potential of parallelism when applied to the bounded-tree search phase of FPT algorithms is demonstrated, thereby allowing even larger problem instances to be solved in practice.

TL;DR: It is proved that the problem of auditing databases which support statistical sum queries to protect the security of sensitive information is NP-hard even in the two-dimensional case, and two efficient algorithms are proposed.

TL;DR: The main contribution of the present paper is to trace a fairly tight boundary of decidability for typechecking with data values for XML queries.

TL;DR: A fully polynomial approximation scheme which solves the Subset-Sum Problem with accuracy e in time O(min{n .

TL;DR: Using a general proof technique based on the Turing machine halting problem, it is proved that Perfect Code belongs to W, Steiner Tree belongs toW, and α-Balanced Separator, Maximal Irredundant Set, and Bounded DFA Intersection belong to W.

TL;DR: A class of powerful relational transducers based on Gurevich's abstract state machines are introduced and it is shown that several verification problems related to electronic commerce applications are decidable for these transducers.

TL;DR: It is shown that the decision problem for the temporal logic with the strict until operator over general linear time is PSPACE-complete and shows that it is no harder to reason with arbitrary linear orderings than with discrete linear time temporal logics.

TL;DR: This work presents a general model for schedules with pipelining, and shows that finding a valid schedule with minimum cost is NP-hard, and presents a greedy heuristic for finding good schedules.

TL;DR: It is proved that the graph isomorphism problem restricted to trees and to colored graphs with color multiplicities 2 and 3 is many-one complete for several complexity classes within NC2 and that testing isomorphicism of two trees encoded as pointer lists is L-complete.

TL;DR: This work defines relative containment, which formalizes the notion of query containment relative to the sources available to the data-integration system, and provides optimal bounds for relative containment for several important classes of datalog queries, including the common case of conjunctive queries.

TL;DR: It is proved in this paper that the MIN-CVCB problem is NP-complete and a parameterized algorithm is developed for the problem, in which classical results in matching theory and recently developed techniques in parameterized computation theory are nicely combined and extended.

TL;DR: It is proved the W[2]-completeness of the feature subset selection problem when the cardinality of the subset is the parameter.

TL;DR: This paper shows that for minimal k, the MQI problem is fixed-parameter tractable and that in the case of a small number k of "errors" the tree reconstruction can be done efficiently.

TL;DR: The key notion of glueable select&verify graph problems is coined and a prospective way to easily check whether a planar graph problem will allow for a fixed parameter algorithm of running time c√kno(1) for constant c is derived.

TL;DR: A technique for two-dimensional substring indexing based on a reduction to the geometric problem of identifying common colors in two ranges containing colored points is presented and results in a family of secondary memory index structures that trade space for time, with no loss of accuracy.

TL;DR: This work presents an efficient offline algorithm and improves both the lower and upper bounds on the competitive ratio of online algorithms and proves three lower bound results concerning resource augmentation in both metered task models.

TL;DR: Stable long-lived consensus systems are proposed, and tight lower bounds on the achievable stability are proved, for several different scenarios including systems that keep memory from one invocation of consensus to the next versus memoryless systems.

TL;DR: It is proved the existence of asymptotic firing throughputs for all transitions in the net, and the vector of the throughputs at the different transitions is explicitly computable up to a multiplicative constant.