Metric random matchings with applications
نویسنده
چکیده
Let ({1, 2, . . . , n}, d) be a metric space. We analyze the expected value and the variance of ∑bn/2c i=1 d(π(2i − 1),π(2i)) for a uniformly random permutation π of {1, 2, . . . , n}, leading to the following results: • Consider the problem of finding a point in {1, 2, . . . , n} with the minimum sum of distances to all points. We show that this problem has a randomized algorithm that (1) always outputs a (2 + )-approximate solution in expected O(n/ 2) time and that (2) inherits Indyk’s [9, 10] algorithm to output a (1 + )-approximate solution in O(n/ 2) time with probability Ω(1), where ∈ (0, 1). • The average distance in ({1, 2, . . . , n}, d) can be approximated in O(n/ ) time to within a multiplicative factor in [ 1/2 − , 1 ] with probability 1/2 + Ω(1), where > 0. • Assume d to be a graph metric. Then the average distance in ({1, 2, . . . , n}, d) can be approximated in O(n) time to within a multiplicative factor in [ 1− , 1 + ] with probability 1/2 + Ω(1), where = ω(1/n1/4).
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ورودعنوان ژورنال:
- CoRR
دوره abs/1703.08433 شماره
صفحات -
تاریخ انتشار 2017