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  • 1
    Electronic Resource
    Electronic Resource
    An efficient parallel algorithm for shortest paths in planar layered digraphs (1995)
    Springer
    Algorithmica 14 (1995), S. 322-339 
    Details
    ISSN: 1432-0541
    Keywords: Parallel algorithms ; Shortest paths ; Planar separators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Computing shortest paths in a directed graph has received considerable attention in the sequential RAM model of computation. However, developing a polylog-time parallel algorithm that is close to the sequential optimal in terms of the total work done remains an elusive goal. We present a first step in this direction by giving efficient parallel algorithms for shortest paths in planar layered digraphs. We show that these graphs admit special kinds of separators calledone- way separators which allow the paths in the graph to cross it only once. We use these separators to give divide- and -conquer solutions to the problem of finding the shortest paths between any two vertices. We first give a simple algorithm that works in the CREW model and computes the shortest path between any two vertices in ann-node planar layered digraph in timeO(log2 n) usingn/logn processors. We then use results of Aggarwal and Park [1] and Atallah [4] to improve the time bound toO(log2 n) in the CREW model andO(logn log logn) in the CREW model. The processor bounds still remain asn/logn for the CREW model andn/log logn for the CRCW model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294130
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Valence Charge Fluctuations and Tc Retention in Tl1−xPbxSr1+xLa1−xCuO5−y (0.0 ≤ x ≤0.5) System (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 139-140 
    Details
    ISSN: 1572-9605
    Keywords: XPS ; Cuprate Superconductor ; Valence fluctuations ; Tc retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Structural and x-ray photoelectron spectroscopy (XPS) studies of the Tl1−xPbxSr1+xLa1−xCuO5−y (0.0≤x≤0.5) system have been carried out. The unit cell parameters increase with x. Irrespective of x the Tc is retained in this series and the optimum hole concentration (nh) is maintained for x≤ 0.5. An increase in Tl 4f and O ls binding energy with x suggests a reduction in their oxidation state. Origin of holes is discussed in terms of charge transfer between Tl, Pb and CuO2 layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022639525484
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    Paper (German National Licenses)
    Fulltext
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