1,720,999 research outputs found

    Rational queueing

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    Min sum clustering with penalties

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    Given a complete graph G=(V,E), a weight function on its edges, and a penalty function on its vertices, the penalized k-min-sum problem is the problem of finding a partition of V to k+1 sets, S1,...,Sk+1, minimizing , where for , and p(S)=[summation operator]i[set membership, variant]Spi. Our main result is a randomized approximation scheme for the metric version of the penalized 1-min-sum problem, when the ratio between the minimal and maximal penalty is bounded. For the metric penalized k-min-sum problem where k is a constant, we offer a 2-approximation.Min sum clustering Outliers Randomized approximation scheme

    The maximum saving partition problem

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    The input to the MAXIMUM SAVING PARTITION PROBLEM consists of a set V= 1,…,n , weights wi, a function f, and a family S of feasible subsets of V. The output is a partition (S1,…,Sl) such that Siset membership, variantS, and View the MathML source is maximized. We present a general View the MathML source-approximation algorithm, and improved algorithms for special cases of the function f.ou

    Flow trees for vertex-capacitated networks

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    AbstractGiven a graph G=(V,E) with a cost function c(S)⩾0∀S⊆V, we want to represent all possible min-cut values between pairs of vertices i and j. We consider also the special case with an additive cost c where there are vertex capacities c(v)⩾0 ∀v∈V, and for a subset S⊆V, c(S)=∑v∈Sc(v). We consider two variants of cuts: in the first one, separation, {i} and {j} are feasible cuts that disconnect i and j. In the second variant, vertex-cut, a cut-set that disconnects i from j does not include i or j. We consider both variants for undirected and directed graphs. We prove that there is a flow-tree for separations in undirected graphs. We also show that a compact representation does not exist for vertex-cuts in undirected graphs, even with additive costs. For directed graphs, a compact representation of the cut-values does not exist even with additive costs, for neither the separation nor the vertex-cut cases
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