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  • Articles: DFG German National Licenses  (2)
  • 05B40  (1)
  • Dewey (17th): 651.8  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    BIT 10 (1970), S. 443-456 
    ISSN: 1572-9125
    Keywords: Dewey (17th): 651.8 ; U.D.C.: 007 681.322.025 ; Trees ; search Structures ; data ; file ; tree Information Retrieval
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract An important property of file structures is their behavior when the underlying distribution of access frequencies is non-uniform. In this note we consider methods for structuring files so that initially unknown but non-uniform access frequencies are exploited in a way that reduces mean search times. As a specific illustration a simple algorithm is applied to sequence search trees and shown to produce structures with mean search times that are significantly less than those produced by an algorithm creating tree structures independent of access frequencies. An analytic result is obtained for this improvement when access frequencies are uniform. Samples from the results of Monte Carlo simulations are used to illustrate this improvement when access frequencies are non-uniform.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Probability theory and related fields 102 (1995), S. 105-121 
    ISSN: 1432-2064
    Keywords: 60D05 ; 05B40 ; 52A22
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary Letn random intervalsI 1, ...,I n be chosen by selecting endpoints independently from the uniform distribution on [0.1]. Apacking is a pairwise disjoint subset of the intervals; itswasted space is the Lebesgue measure of the points of [0,1] not covered by the packing. In any set of intervals the packing with least wasted space is computationally easy to find; but its expected wasted space in the random case is not obvious. We show that with high probability for largen, this “best” packing has wasted space $$O(\frac{{\log ^2 n}}{n})$$ . It turns out that if the endpoints 0 and 1 are identified, so that the problem is now one of packing random arcs in a unit-circumference circle, then optimal wasted space is reduced toO(1/n). Interestingly, there is a striking difference between thesizes of the best packings: about logn intervals in the unit interval case, but usually only one or two arcs in the circle case.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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