4/24/2021 0 Comments Axcent Zero User Manual
First, the storage capacity is limited (10h of MPEG-2 video need about 18 GB).Relying on that specific structure, effective variable fixing algorithms (VFAs) are only suited for the problems they have been designed for.Frequently, new combinatorial optimization problems evolve as a combination of simpler structured problems.
For such combinations, we show how VFAs for linear optimization problems can be coupled via Lagrangian relaxation. ![]() Axcent Zero User Free Public FullDiscover the worlds research 19 million members 135 million publications 700k research projects Join for free Public Full-text 1 Content uploaded by Meinolf Sellmann Author content All content in this area was uploaded by Meinolf Sellmann on Nov 19, 2014 Content may be subject to copyright. V ariable xing is an important technique when solving combinato- rial optimization problems. Unique protable variable values are detected with respect to the objective function and to the constraint structure of the problem. Relying on that specic structure, effective v ariable xing algorithms (VFAs) are only suited for the problems they have been designed for. Frequently, new com- binatorial optimization problems evolve as a combination of simpler structured problems. ![]() Introduction Reduction algorithms are of great importance when combinatorial optimization prob- lems have to be solved exactly. The tightening of problem formulations within a branch- and-bound approach improves on the quality of the bounds computed as well as on the approachs robustness. Gi ven a maximization problem P ( x ) where x 0, 1 n, n I N, the idea of variable xing is to use upper bound information to detect unique protable assignments for a variable: If an upper bound on P ( x x i k ), k 0, 1, drops below the best known solution v alue, then we can set x i 1 k. Frequently, constraints of optimization problems can be grouped such that the o ver- all problem can be viewed as a combination of two or more simpler structured problems. Assuming that efcient variable xing algorithms (VF As) for these subproblems exist, their independent application usually does not yield an effective algorithm to perform variable xing for the combined problem. The reason for this is that tight bounds on the objective cannot be obtained by taking only a subset of the constraints into account. This work was partly supported by the German Science Foundation (DFG) project SFB-376, by the UP -T V project, partially funded by the IST program of the Commission of the Eu- ropean Union as project number 1999-20 751, and by the IST Programme of the EU under contract number IST -1999-14186 (ALCOM-FT). The paper is structured as follows: In Section 2, we introduce the Automatic Record- ing Problem, that can be viewed as a combination of a knapsack problem and a MWSSP on interval graphs. In Section 3, we introduce an efcient VF A for the latter problem. Finally, in Section 5 we gi ve numerical results. The Automatic Recording Pr oblem The Automatic Recording Pr oblem (ARP) is an example of a problem that is constituted by two simpler substructures. W e focus on algorithms that solve the problem exactly and give a tightened formulation of the ARP as an integer program (IP). The technology of digital television offers new possibilities for indi vidualized ser- vices that cannot be provided by nowadays analog broadcasts. Additional information like classication of content, or starting and ending times can be submitted within the digital broadcast stream. With those informations at hand, new services can be pro vided that make use of individual proles and maximize customer satisfaction. One service which is available already today is an intelligent digital video recorder that is aware of its users preferences and records automatically (see 2). The recorder tries to match a given user prole with the information submitted by the differ - ent TV channels. E.g., a user may be interested in thrillers, the more recent the better. ![]() As the number of channels may be enormous (more than 100 digital channels are possible), a service that automatically provides an individual selection is highly appreciated and subject of current research activities (for example within projects like UP-TV funded by the European Union or the TV-Anytime F orum ).
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