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OPTIMIZATION LETTERS 2025年第2期19卷 329-345页

作者： Gerbner, Daniel Keszegh, Balazs Nagy, Kartal Patkos, Balazs Wiener, Gabor Alfred Reny Inst Math Budapest Hungary Eotvos Lorand Univ Budapest Hungary Budapest Univ Technol & Econ Dept Comp Sci & Informat Theory Budapest Hungary

In the game theoretical approach of the basic problem in combinatorial search an adversary thinks of a defective element d of an n-element pool X, and the questioner needs to find x by asking questions of type is d is an element of Q ? \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$d\in Q?$$\end{document} for certain subsets Q of X. We study cooperative versions of this problem, where there are multiple questioners, but not all of them learn the answer to the queries. We consider various models that differ in how it is decided who gets to ask the next query, who obtains the answer to the query, and who needs to know the defective element by the end of the process.

关键词： Cooperative search combinatorial search search game

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combinatorial search versus genetic algorithms:: A case study based on the generalized median graph problem

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PATTERN RECOGNITION LETTERS 1999年第11-13期20卷 1271-1277页

作者： Bunke, H Münger, A Jiang, XY Univ Bern Dept Comp Sci Inst Informat & Angew Math CH-3012 Bern Switzerland

The computation of generalized median graphs (the graph with the smallest average edit distance to all graphs in a given set of graphs) is highly computationally complex. As a matter of fact, it is exponential in the number of nodes of the union of all graphs under consideration. Thus, the generalized median graph computation problem seems to be a suitable and challenging testbed for a comparison of combinatorial search and genetic algorithms. Two solutions are described in this paper. The first is an exact algorithm based on combinatorial search, while the second is a genetic algorithm. Both approaches are compared to each other in a series of experiments. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： generalized median graph combinatorial search genetic algorithm

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combinatorial search in two and more rounds

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THEORETICAL COMPUTER SCIENCE 2019年第0期780卷 1-11页

作者： Damaschke, Peter Chalmers Univ Dept Comp Sci & Engn S-41296 Gothenburg Sweden

In a combinatorial search problem we wish to identify an unknown element by binary tests, where the edges of a hypergraph specify the available tests. We show that, for rather general cases of this problem, the worst-case minimum number of tests, even if adaptive testing is permitted, can already be achieved in a small number of rounds of parallel tests. In particular, the maximum number of necessary rounds grows only as the square root of the number of elements, and two rounds are enough if, e.g., the test number is close to the number of elements, or the hypergraph is a graph. We also provide polynomial-time, hardness, and parameterized results on the computational complexity of finding optimal strategies for some cases, including graphs and tree hypergraphs. (C) 2019 Elsevier B.V. All rights reserved.

关键词： combinatorial search Test cover Adaptive strategy Matching

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combinatorial search to optimize vent locations in the presence of disturbances in liquid composite molding processes

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MATERIALS AND MANUFACTURING PROCESSES 2003年第2期18卷 261-285页

作者： Gokce, A Advani, S Univ Delaware Dept Mech Engn Newark DE 19716 USA

In liquid composite molding processes, the resin is injected into a mold cavity containing preplaced reinforcement fabrics through openings known as gates, and the air leaves the mold through openings called as vents. Under nominal conditions, the last points to fill are chosen as vent locations. However, due to imperfect preform placement, gaps and channels may form along the edges and at curvatures in a mold, offering a path with less resistance for resin flow. The faster advance of resin through these gaps and channels, a common disturbance, known as racetracking, will cause the last filled regions to vary, which complicates the vent selection process. We introduce a methodology that uses set and probability theories to forecast racetracking conditions in a mold and have developed a combinatorial search algorithm to locate corresponding optimal vent locations. The accuracy, efficiency and usefulness of the approach is illustrated with three case studies.

关键词： liquid composite molding resin transfer molding optimization vent optimization combinatorial search fiber composites resin flow

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combinatorial search of Magnetostrictive Materials for Sensors

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ELECTRONICS AND COMMUNICATIONS IN JAPAN 2014年第9期97卷 342-U3页

作者： Maetani, Takuya Nakamitsu, Yutaka Sakurai, Junpei Nakagawa, Shigeki Hata, Seiichi Tokyo Inst Technol Sch Engn Control & Syst Engn Tokyo Japan Tokyo Inst Technol Precis & Intelligence Lab Tokyo Japan Tokyo Inst Technol Grad Sch Engn Dept Phys Elect Tokyo Japan FTS Corp NFTS R&D Tokyo Japan Nagoya Univ Grad Sch Engn Nagoya Aichi 4648601 Japan

combinatorial search is one of the useful methods that could search for optimal composition of alloy materials or novel alloy materials. combinatorial sputtering provides sample group (library) having different compositions in a limited place. Then, the properties of the samples can be scanned in an efficient way. In this research, magnetostrictive material with high magnetostriction, relative permeability, and resistivity was studied. Desired value of magnetostriction is more than 20 x 10(-6), relative permeability is more than 4000, and resistivity is more than 100 mu ***. As a result, composition that Cr content is less than 14 at.% fill the desired value of relative permeability, and more than 10 at.% fill the desired value of resistivity. There is possibility to fill the desired value of magnetostriction. (C) 2014 Wiley Periodicals, Inc. Published online in Wiley Online Library (***).

关键词： magnetostrictive material combinatorial search

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Rounds in a combinatorial search problem

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DISCRETE APPLIED MATHEMATICS 2020年第0期276卷 60-68页

作者： Gerbner, Daniel Vizer, Mate MTA Renyi Inst Realtanoda Utca 13-15 H-1053 Budapest Hungary

We consider the following combinatorial search problem: there are some unknown elements of [n], called excellent, and we should find at least one, asking questions of the following type: "Is there an excellent element in A subset of [n]?". Katona in 2011 proved sharp results for the number of questions needed to ask in the adaptive, non-adaptive and two-round versions of this problem. We verify a conjecture of Katona by proving that in the r-round version we need to ask rn(1/r) + O-r(1) questions for fixed r and this is sharp. We also prove bounds for the questions needed to ask if we want to find at least d excellent elements. (C) 2019 Elsevier B.V. All rights reserved.

关键词： combinatorial search Adaptive Non-adaptive Rounds

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Generic Exact combinatorial search at HPC Scale

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INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING 2023年第1期51卷 83-106页

作者： MacGregor, Ruairidh Archibald, Blair Trinder, Phil Univ Glasgow Sch Comp Sci Glasgow Scotland

Exact combinatorial search is essential to a wide range of important applications, and there are many large problems that need to be solved quickly. searches are extremely challenging to parallelise due to a combination of factors, e.g. searches are non-deterministic, dynamic pruning changes the workload, and search tasks have very different runtimes. YewPar is a C++/HPX framework that generalises parallel search by providing a range of sophisticated search *** paper demonstrates generic high performance combinatorial search, i.e. that a variety of exact combinatorial searches can be easily parallelised for HPC using YewPar. We present a new mechanism for profiling key aspects of YewPar parallel combinatorial search, and demonstrate its value. We exhibit, for the first time, generic exact combinatorial searches at HPC scale. We baseline YewPar against state-of-the-art sequential C++ and C++/OpenMP implementations. We demonstrate that deploying YewPar on an HPC system can dramatically reduce the runtime of large problems, e.g. from days to just 100s. The maximum relative speedups we achieve for an enumeration search are near-linear up to 195(6825) compute-nodes(workers), super-linear for an optimisation search on up to 128(4480) (pruning reduces the workload), and sub-linear for decision searches on up to 64(2240) compute-nodes(workers).

关键词： combinatorial search Parallel skeletons Constraint programming High performance computing

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Organizing a Successful Artificial Intelligence Online Conference: Lessons from the 13th Symposium on combinatorial search

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AI MAGAZINE 2021年第1期42卷 76-82页

作者： Harabor, Daniel Vallati, Mauro Monash Univ Clayton Vic Australia Univ Huddersfield Huddersfield W Yorkshire England

The 13th Symposium on combinatorial search (SoCS) was held May 26 to 28, 2020. Originally scheduled to take place in Vienna, Austria, the symposium pivoted toward a fully online technical program in early March. As an in- person event, SoCS offers participants a diverse array of scholarly activities including technical talks (long and short), poster sessions, plenary sessions, a community meeting and, new for 2020, a Master Class tutorial program. This article describes challenges, approaches, and opportunities associated with adapting these many different activities to the online setting. We consider issues such as scheduling, dissemination, attendee interaction, and community engagement before, during, and after the event. In each case, we report on the approaches taken by SoCS, then give a post hoc analysis of their effectiveness and discuss how these decisions continue to impact the SoCS community in the days after SoCS 2020. This work will be of interest to organizers of similar conferences who may be considering the switch to an online format.

关键词： combinatorial search searching Artificial intelligence Community engagement Combinatorics

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The SAT plus CAS method for combinatorial search with applications to best matrices

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ANNALS OF MATHEMATICS AND ARTIFICIAL INTELLIGENCE 2019年第4期87卷 321-342页

作者： Bright, Curtis Dokovic, Dragomir Z. Kotsireas, Ilias Ganesh, Vijay Univ Waterloo 200 Univ Ave W Waterloo ON Canada Wilfrid Laurier Univ 75 Univ Ave W Waterloo ON Canada

In this paper, we provide an overview of the SAT+CAS method that combines satisfiability checkers (SAT solvers) and computer algebra systems (CAS) to resolve combinatorial conjectures, and present new results vis-a-vis best matrices. The SAT+CAS method is a variant of the Davis-Putnam-Logemann-Loveland DPLL(T) architecture, where the T solver is replaced by a CAS. We describe how the SAT+CAS method has been previously used to resolve many open problems from graph theory, combinatorial design theory, and number theory, showing that the method has broad applications across a variety of fields. Additionally, we apply the method to construct the largest best matrices yet known and present new skew Hadamard matrices constructed from best matrices. We show the best matrix conjecture (that best matrices exist in all orders of the form r(2) + r + 1) which was previously known to hold for r <= 6 also holds for r = 7. We also confirmed the results of the exhaustive searches that have been previously completed for r <= 6.

关键词： Satisfiability checking combinatorial search Symbolic computation SAT plus CAS

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Differential evolution and combinatorial search for constrained index-tracking

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ANNALS OF OPERATIONS REsearch 2009年第1期172卷 153-176页

作者： Krink, Thiemo Mittnik, Stefan Paterlini, Sandra Univ Modena & Reggio E Dept Econ CEFIN I-41100 Modena Italy Univ Modena & Reggio E RECent I-41100 Modena Italy Allianz Invest Management SE D-80802 Munich Germany Univ Munich Ctr Quantitat Risk Anal Dept Stat D-80799 Munich Germany Ctr Financial Studies D-60323 Frankfurt Germany

Index-tracking is a low-cost alternative to active portfolio management. The implementation of a quantitative approach, however, is a major challenge from an optimization perspective. The optimal selection of a group of assets that can replicate the index of a much larger portfolio requires both to find the optimal subset of assets and to fine-tune their weights. The former is a combinatorial, the latter a continuous numerical problem. Both problems need to be addressed simultaneously, because whether or not a selection of assets is promising depends on the allocation weights and vice versa. Moreover, the problem is usually of high dimension. Typically, an optimal Subset of 30-150 positions out of 100-600 need to be selected and their weights determined. search heuristics can be a valuable alternative to traditional methods, which often cannot deal with the problem. In this paper, we propose a new optimization method, which is partly based on Differential Evolution (DE) and on combinatorial search. The main advantage of our method is that it can tackle the index-tracking problem as complex as it is, generating accurate and robust results.

关键词： Index-tracking Passive asset management Differential evolution combinatorial search

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