109,018 research outputs found

    Splitters and Decomposers for Binary Matroids

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    Let EX[M1…,Mk]EX[M_1\dots, M_k] denote the class of binary matroids with no minors isomorphic to M1,…,MkM_1, \dots, M_k. In this paper we give a decomposition theorem for EX[S10,S10βˆ—]EX[S_{10}, S_{10}^*], where S10S_{10} is a certain 10-element rank-4 matroid. As corollaries we obtain decomposition theorems for the classes obtained by excluding the Kuratowski graphs EX[M(K3,3),Mβˆ—(K3,3),M(K5),Mβˆ—(K5)]EX[M(K_{3,3}), M^*(K_{3,3}), M(K_5), M^*(K_5)] and EX[M(K3,3),Mβˆ—(K3,3)]EX[M(K_{3,3}), M^*(K_{3,3})]. These decomposition theorems imply results on internally 44-connected matroids by Zhou [\ref{Zhou2004}], Qin and Zhou [\ref{Qin2004}], and Mayhew, Royle and Whitte [\ref{Mayhewsubmitted}].Comment: arXiv admin note: text overlap with arXiv:1403.775

    Towards a splitter theorem for internally 4-connected binary matroids

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    This is the post-print version of the Article - Copyright @ 2012 ElsevierWe prove that if M is a 4-connected binary matroid and N is an internally 4-connected proper minor of M with at least 7 elements, then, unless M is a certain 16-element matroid, there is an element e of E(M) such that either M\e or M/e is internally 4-connected having an N-minor. This strengthens a result of Zhou and is a first step towards obtaining a splitter theorem for internally 4-connected binary matroids.This study is partially funded by Marsden Fund of New Zealand and the National Security Agency

    The Visvalingam algorithm: metrics, measures and heuristics

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    This paper provides the background necessary for a clear understanding of forthcoming papers relating to the Visvalingam algorithm for line generalisation, for example on the testing and usage of its implementations. It distinguishes the algorithm from implementation-specific issues to explain why it is possible to get inconsistent but equally valid output from different implementations. By tracing relevant developments within the now-disbanded Cartographic Information Systems Research Group (CISRG) of the University of Hull, it explains why a) a partial metric-driven implementation was, and still is, sufficient for many projects but not for others; b) why the Effective Area (EA) is a measure derived from a metric; c) why this measure (EA) may serve as a heuristic indicator for in-line feature segmentation and model-based generalisation; and, d) how metrics may be combined to change the order of point elimination. The issues discussed in this paper also apply to the use of other metrics. It is hoped that the background and guidance provided in this paper will enable others to participate in further research based on the algorithm

    Comment on "Multiple Bosonic Mode Coupling in Electron Self-Energy of (La2βˆ’x_{2-x}Srx_x)CuO4_4"

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    We calculate the photoemission spectral response using the extracted Ξ±2F\alpha^2F of Zhou et al (cond-mat/0405130) as an input and we find that the reported ReΞ£\Sigma has more strucure than physically possible. Therefore, the "fine structure" most likely reflects the experimental noise.Comment: Comment on cond-mat/0405130, "energy resolution" improve
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