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Implementation of approximation algorithms for weighted and unweighted edge-disjoint paths in bidirected trees

ACM Journal of Experimental Algorithmics 2002年 7卷

作者： Erlebach, Thomas Jansen, Klaus Computer Engineering and Networks Laboratory (TIK) ETH Zürich Gloriastrasse 35 Zürich 8092 Switzerland Institute for Computer Science and Applied Mathematics Christian-Albrechts-Universität zu Kiel Olshausenstr. 40 Kiel 24098 Germany

Given a set of weighted directed paths in a bidirected tree, the maximum weight edge-disjoint paths problem (MWEDP) is to select a subset of the given paths such that the selected paths are edge-disjoint and the total weight of the selected paths is maximized. MWEDP is script Nscript P-hard for bidirected trees of unbounded degree, even if all weights are the same (the unweighted case). Three different approximation algorithms are implemented: a known combinatorial (5/3 + ε)-approximation algorithm A₁ for the unweighted case, a new combinatorial 2-approximation algorithm A₂ for the weighted case, and a known (5/3 + ε)-approximationalgorithm A₃ for the weighted case that is based on linear programming. For algorithm A₁, it is shown how efficient data structures can be used to obtain a worst-case running-time of O(m + n + 4^1/ε √n·m) for instances consisting of m paths in a tree with n nodes. Experimental results regarding the running-times and the quality of the solutions obtained by the three approximation algorithms are reported. Where possible, the approximate solutions are compared to the optimal solutions, which were computed by running CPLEX on an integer linear programming formulation of MWEDP. © 2002, Association for Computing Machinery. All rights reserved.

关键词： Algorithms Combinatorial optimization Experimentation F.2.2 [analysis of algorithms and problem complexity]: nonnumerical algorithms and problems - computations on discrete structures Linear programming

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A generic and modular internet charging system for the cumulus pricing scheme

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Journal of Network and Systems Management 2001年第3期9卷 293-325页

作者： Stiller, Burkhard Reichl, Peter Gerke, Jan Flury, Placi Computer Engineering and Networks Laboratory TIK Swiss Federal Institute of Technology ETH Zürich Switzerland FTW Wien Austria

Pricing and charging are important management functions which future commercial networks will have to offer. Since the Internet is on the move to provide differentiated services, suitable and scalable management mechanisms are required for the backbone based on the Differentiated Services (DiffServ) Architecture. Since network management following actual market forces has to implement a price-driven and charge-driven approach for managing the usage of services, this paper introduces as a first contribution the design of a generic and modular Internet Charging System (ICS), offering a service-independent architecture and integrating economically controlled network management functions into present Internet technology. Moreover, a central part of this ICS, i.e., the Internet Charge Calculation and Accounting System (ICCAS), is presented in more detail and offers necessary user support functions. The second main contribution of the paper focuses on the newly developed Cumulus Pricing Scheme (CPS). CPS is unique to define clear relations between different time-scales for accounting, monitoring, and charging activities. Charges in this schemes are based on flat fees and, hence, are predictable and transparent, whereas, unlike pure flat rate schemes, the incorporated feedback mechanism nevertheless allows to take market forces into account. Finally, it is demonstrated how the ICCAS is well-suited to integrate both DiffServ technology and CPS. © 2001 Plenum Publishing Corporation.

关键词： Charging Architecture Differentiated services Internet pricing model Service level agreements

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Management of differentiated services usage by the Cumulus pricing scheme and a generic Internet charging system 7

Management of differentiated services usage by the Cumulus p...

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7th IEEE/IFIP International Symposium on Integrated Network Management, IM 2001

作者： Stiller, B. Gerke, J. Reichl, P. Flury, P. ETH Zürich Computer Engineering and Networks Laboratory TIK Gloriastrasse 35 ZürichCH - 8092 Switzerland

ISBN: (纸本)0780367197

Since the Internet is on the move to provide differentiated services, for the backbone based on the differentiated services architecture (DiffServ), suitable management mechanisms are required. Scalable solutions for overload management are a must, such as economically-driven functions of charging and pricing. Future commercial networks need to offer as well a new view of pricing, considered as management information. Therefore, the Cumulus pricing scheme (CPS) explicitly proposed here for the DiffServ technology is the only approach known so far, which defines a clear relation between different time scales of measurement, accounting, and charging periods. The scheme is flexible enough to allow network management according to actual forces of the market. CPS's implementation is supported by a designed generic Internet charging system offering a service-independent architecture and integrating interchangeably economically-controlled network management functions of charge calculation and pricing. In particular, it has been applied to DiffServ and the new CPS. © 2001 IEEE.

关键词： computer architecture

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Management of differentiated services usage by the Cumulus pricing scheme and a generic Internet charging system

Management of differentiated services usage by the Cumulus p...

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IFIP/IEEE International Symposium on Integrated Network Management

作者： B. Stiller J. Gerke P. Reichl P. Flury Computer Engineering and Networks Laboratory TIK ETH Zurich Zurich Switzerland

ISBN: (纸本)0780367197

关键词： Pricing Web and internet services Diffserv networks Technology management IP networks Spine computer networks Laboratories Electronic mail computer architecture

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Pricing and Cost Recovery for Internet Services: Practical Review, Classification, and Application of Relevant Models

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Netnomics 2001年第2期3卷 149-171页

作者： Stiller, Burkhard Reichl, Peter Leinen, Simon Computer Engineering and Networks Laboratory TIK ETH Zürich Zürich Switzerland SWITCH Zürich Switzerland

Suitable pricing models for Internet services represent one of the main prerequisites for a successfully running implementation of a charging and accounting system. This paper introduces general aspects influencing the choice of a pricing model in practical situations and presents a survey as well as a classification of relevant and advanced approaches to be found in the scientific literature. First performance results on charging extensions within the Internet are presented, which are completed by a set of market price simulations for dynamic pricing models within the same implementation environment. Based on cost model investigations some detailed insights into price and cost issues from an Internet Service Provider's (ISP) point of view are given. Moreover, current challenges as well as problems are discussed in a practical context as investigated in the Swiss National Science Foundation project Charging and Accounting Technology for the Internet (CATI).

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Internal design representations for embedded systems

Internal design representations for embedded systems

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IEEE International Conference on computer-Aided Design

作者： L. Thiele Computer Engineering and Networks Laboratory TIK Swiss Federal Institute of Technology Zurich Switzerland

Modern embedded computing systems tend to be heterogeneous assemblages of concurrent subsystems, typically described in different languages and semantics which are well established in the various application fields. For example, the specification of the functional and timing behavior necessitates a mixture of different basic models of computation and communication which come from transformatlive or reactive domains. There is little hope that a single language will replace this heterogeneous set of languages. In fact, experiments with system specification languages show that there is not a unique universal specification language to support the whole life cycle. A similar problem occurs when reused components shall be integrated, possibly described in another language and incompletely documented. Examples would be components of other companies or "legacy code". The lack of coherency of the different languages, methods and toots is a substantial obstacle on the way to higher design productivity and design quality. A design process must be able to bridge the semantic differences for verification and synthesis and should account for limited knowledge of system properties. This paper describes approaches which allow for the common representation of different languages and incomplete specifications. In particular, recent results on the use of internal design representations targeted to scheduling and design space exploration are reviewed. The information useful for methods like allocation of resources, partitioning the design and scheduling must be estimated or extracted from the various input languages and mapped onto internal representations which describe properties of the subsystems and their coordination. Design methods work on these internal representations and eventually refine them by adding components and reducing non-determinism.

关键词： Embedded system Specification languages Embedded computing Assembly systems Timing Computational modeling Productivity Process design Bridges

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Semsomm-a scalable multiple encryption scheme for one-to-many multicast

Semsomm-a scalable multiple encryption scheme for one-to-man...

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IEEE International Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises (WET ICE)

作者： N. Weiler Computer Engineering and Networks Laboratory (TIK) Swiss Federal Institute of Technology ETH Zurich Switzerland

Many traditional and new Internet multi-party applications require a scalable, secure group communication infrastructure. Some of these applications such as video conferencing involve many-to-many communication while others such as stock exchange systems engage in one-to-many data distribution. In this paper, we present a novel solution for the latter area. Our approach, which we call Semsomm, relies on two main ideas: First, we use intermediate nodes of the multicast distribution tree as entrusted relaying nodes in order to overcome the need to re-key the entire group upon each membership change. Second, the session key is periodically renewed and redistributed to legitimate group members, thus inhibiting any collusion attack. Semsomm scales to very large groups while preserving perfect forward secrecy of the multicasted data information because of its multiple encryption method. Furthermore, we show how our approach can be extended first to few-to-many and then to many-to-many scenarios with the appropriate network based infrastructural enhancements such as active networks.

关键词： Cryptography Scalability Application software Security computer networks Laboratories IP networks Videoconference Relays Tires

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Multiobjective genetic programming: reducing bloat using SPEA2

Multiobjective genetic programming: reducing bloat using SPE...

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Congress on Evolutionary Computation

作者： S. Bleuler M. Brack L. Thiele E. Zitzler Computer Engineering and Communication Networks Laboratory TIK Swiss Federal Institute of Technology Zurich Switzerland

ISBN: (纸本)0780366573

This study investigates the use of multiobjective techniques in genetic programming (GP) in order to evolve compact programs and to reduce the effects caused by bloating. The proposed approach considers the program size as a second, independent objective besides the program functionality. In combination with a multiobjective evolutionary technique, SPEA2, this method outperforms four other strategies to reduce bloat with regard to both convergence speed and size of the produced programs on an even-parity problem.

关键词： Genetic programming computer networks Genetic engineering Communication networks Convergence Time measurement Training data Optimization methods

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Mobility in a future Internet

Mobility in a future Internet

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Conference on Local computer networks (LCN)

作者： B. Stiller L. Kacnelson C.E. Perkins P. Dini Computer Engineering and Networks Laboratory TIK Swiss Federal Institute of Technology Switzerland Adrecom Baltimore MD USA Nokia Research Center Mountain View CA USA Cisco Systems Inc. San Jose CA USA

ISBN: (纸本)0769513212

Mobility of users in a future Internet has become a reality due to highly mobile end-systems. However, the new dimension of protocol functionality, Mobile IP, resource control, quality of service (QoS) support and AAA (authentication, authorization and accounting) features extended by charging schemes are still to be integrated effectively. Therefore, this position paper addresses these three areas of research concern, discusses basic concepts and outlines major problem fields still to be worked on.

关键词： Mobile communication Wireless LAN IP networks Protocols Satellite broadcasting Network servers GSM Web and internet services Authentication Authorization

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Active technologies for network and service management: Report on DSOM'99

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Journal of Network and Systems Management 2000年第1期8卷 125-130页

作者： Stadler, Rolf Stiller, Burkhard Columbia University New York NY 10027 United States TIK ETH Zürich Switzerland Columbia University United States Department of Computer Engineering and Networks Laboratory TIK Swiss Federal Institute of Technology ETH Zürich Switzerland

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