Showing papers in "Journal of Computer and System Sciences in 2006"
TL;DR: It is proved that the NP-hard distinguishing substring selection problem has no polynomial time approximation schemes of running time f(1/@e)n^o^(^1^/^@e^) for any function f unless an unlikely collapse occurs in parameterized complexity theory.
313 citations
TL;DR: This paper proposes a new password authentication scheme that can support the Diffie-Hellman key agreement protocol over insecure networks and users and the system can use the agreed session key to encrypt/decrypt their communicated messages using the symmetric cryptosystem.
279 citations
TL;DR: It is shown that the NP-complete Feedback Vertex Set problem, which asks for the smallest set of vertices to remove from a graph to destroy all cycles, is deterministically solvable in O(c^[email protected]?m) time.
206 citations
TL;DR: This work proves many game theoretic properties of the model, including an easily applied characterization of Nash equilibria, culminating in the showing that allowing selfish users to choose Nash equilibrium strategies is highly undesirable, because the price of anarchy is an unacceptable Θ(n) in the worst case.
198 citations
TL;DR: In this paper, the authors study a generalization of standard property testing where the algorithms are required to be more tolerant with respect to objects that do not have, but are close to having, the property.
146 citations
TL;DR: A model of selfish routing in which the latency experienced by network traffic on an edge of the network is a function of the edge congestion, and network users are assumed to selfishly route traffic on minimum-latency paths is considered.
140 citations
TL;DR: A protocol that constructs the minimum-weight spanning tree (MST) in Õ(μ(G,μ) = w + √n) rounds, where μ( G, μ) is the
117 citations
TL;DR: It has been proved that the methodology proposed in this paper can deal with MADM problems under not only fuzzy environments but also crisp environments.
99 citations
TL;DR: A sharp delineation between classes of SDSs whose behavior is easy to predict and thosewhose behavior is hard to predict is shown, and new PSPACE-hard lower bounds on the complexity of state reachability problems for these models are shown.
90 citations
TL;DR: This schema allows us to define forward algorithms that decide the coverability problem for several classes of systems for which the Karp and Miller procedure cannot be generalized, and for which no complete forward algorithms were known.
88 citations
TL;DR: It is proved that PD2 is also optimal for scheduling "rate-based" tasks whose processing steps may be highly jittered, which generalizes the widely-studied sporadic task model.
TL;DR: A 2-approximation algorithm is given for the weighted version of the capacitated vertex cover problem, improving the Chuzhoy-Naor bound of three and matching (up to lower-order terms) the best approximation ratio known for the vertex-cover problem.
TL;DR: It is shown first that model-checking for globally cooperative (and locally cooperative) HMSCs is decidable within the same complexity as for the restricted class of bounded HMSCs, and secondly that locally cooperative and local-choice HMSCs are always implementable.
TL;DR: These are the first protocols which are provably secure in the standard model (i.e., no random oracles are used for the proof of security) and are reasonably efficient and implementable in practice.
TL;DR: It is shown that SBP is in the polynomial-time hierarchy, between MA and AM on the one hand and between BPP and BPPpath on the other hand, and evidence thatSBP does not coincide with these and other known complexity classes is provided.
TL;DR: Deterministic gossiping in synchronous systems with dynamic crash failures is studied, and gossiping algorithms that are efficient with respect to both time and communication are designed.
TL;DR: It is proved that it is NP-hard to approximate the asymmetric TSP with distances one and two within 321/[email protected] and that it has been shown that the Papadimitriou-Vempala construction is ''local'' in nature and, intuitively, indicates that it cannot be used to obtain hardness factors that grow with the size of the instance.
TL;DR: A set of QoS dimensions with utility function for each dimensions, uses a market model for distributed optimization to maximize the global utility and shows that optimal QoS based resource scheduling involves less overhead and leads to more efficient resource allocation than no optimal resource allocation.
TL;DR: This work proposes a notion of bounded fixed-parameter tractability, where the dependence of the running time on the parameter is restricted to be singly exponential, and develops a basic theory that is centred around the EPT of tractable problems and an EW-hierarchy of classes of intractable problems, both in the bounded sense.
TL;DR: Three secure authentication and key distribution protocols are proposed to provide perfect forward secrecy of these three classes, which are efficient in protecting poorly-chosen passwords chosen by users from guessing attacks and replay attacks.
TL;DR: DELFIN + (DEadLock FINder) is realized, a tool supporting efficient deadlock detection in CCS processes and used to verify a sample of C CS processes, in order to evaluate the method on them.
TL;DR: This work formulate and (approximately) solve hierarchical versions of two prototypical problems in discrete location theory, namely, the metric uncapacitated k-median and facility location problems and yields new insights into hierarchical clustering, a widely used technique in data analysis.
TL;DR: An O(logkloglogk)-approximation algorithm for the k-multicast problem, and, consequently, an O(lognloglogn)- approximation algorithms for the broadcast problem, are devised and an improved bicriteria approximation for the depth-degree problem is derived.
TL;DR: New algorithms based on Fuzzy Logic and Genetic Algorithm which use for CAC and routing many QoS parameters are proposed and implemented and simulation results show that proposed flamework has a good performance and is a promising method for QoS routing and CAC decision.
TL;DR: In this article, the complexity of a wide variety of model-checking problems for nonflat systems under the light of parameterized complexity is investigated, taking the number of synchronized components as a parameter.
TL;DR: This paper analyzes a distributed multi-hop clustering algorithm, mobility-based D-hop (MobDHop), based on two key clustering performance metrics and compares it with other popular clustering algorithms used in MANETs to show that the overhead incurred by multi-Hop clustering has a similar asymptotic bound as 1-hop clusters.
TL;DR: This paper describes this locality-maximizing placement problem and shows that an optimal solution is NP-hard, and describes a polynomial-time algorithm that generates a placement within an additive constant of two from optimal.
TL;DR: The main contributions are methodologies created to quantify the accuracy of network models, methodology to choose the most accurate model for a given network and characteristic of interest (e.g., delay, loss, or error process), and the validation of the data preconditioning modeling algorithms.
TL;DR: A new commit protocol for managing transactions in composite web services is proposed that aims to improve the performance by reducing network delays and the processing time of transactions.
TL;DR: It is shown that rankable entropy rates give upper bounds for time-bounded dimensions, and superranking provides an equivalent definition of polynomial-time dimension.