33,089 research outputs found

    Parallel Deterministic and Stochastic Global Minimization of Functions with Very Many Minima

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    The optimization of three problems with high dimensionality and many local minima are investigated under five different optimization algorithms: DIRECT, simulated annealing, Spall’s SPSA algorithm, the KNITRO package, and QNSTOP, a new algorithm developed at Indiana University

    Transversal designs and induced decompositions of graphs

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    We prove that for every complete multipartite graph FF there exist very dense graphs GnG_n on nn vertices, namely with as many as (n2)−cn{n\choose 2}-cn edges for all nn, for some constant c=c(F)c=c(F), such that GnG_n can be decomposed into edge-disjoint induced subgraphs isomorphic to~FF. This result identifies and structurally explains a gap between the growth rates O(n)O(n) and Ω(n3/2)\Omega(n^{3/2}) on the minimum number of non-edges in graphs admitting an induced FF-decomposition

    Enhancing urban analysis through lacunarity multiscale measurement

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    Urban spatial configurations in most part of the developing countries showparticular urban forms associated with the more informal urban development ofthese areas. Latin American cities are prime examples of this sort, butinvestigation of these urban forms using up to date computational and analyticaltechniques are still scarce. The purpose of this paper is to examine and extendthe methodology of multiscale analysis for urban spatial patterns evaluation. Weexplain and explore the use of Lacunarity based measurements to follow a lineof research that might make more use of new satellite imagery information inurban planning contexts. A set of binary classifications is performed at differentthresholds on selected neighbourhoods of a small Brazilian town. Theclassifications are appraised and lacunarity measurements are compared in faceof the different geographic referenced information for the same neighbourhoodareas. It was found that even with the simple image classification procedure, animportant amount of spatial configuration characteristics could be extracted withthe analytical procedure that, in turn, may be used in planning and other urbanstudies purposes
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