Flow-cut gaps for integer and fractional multiflows
نویسندگان
چکیده
منابع مشابه
Integer multiflows and metric packings beyond the cut condition
Graphs, and more generally matroids, where the simplest possible necessary condition, the ‘Cut Condition’, is also su5cient for multi ow feasibility, have been characterized by Seymour. In this work we exhibit the ‘next’ necessary conditions — there are three of them — and characterize the subclass of matroids where these are also su5cient for multi ow feasibility, or for the existence of integ...
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Let M be a binary matroi d defined on the finite set E(M) and p a function assigning integer values to the elements of E(M). We think of the negative values of p as representing demands and of the nonnegative values as representing capacities. Define F(p) = {e E E(M): p(e) <O}. A flow problem is a pair (M, p). It has a solution if there exists a muir@ox!, that is a function @: V&(M)+ IL!, defin...
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Seymour 10] has characterized graphs and more generally matroids in which the simplest possible necessary condition, the \cut condition", is also suucient for multiiow feasibility. In this work we exhibit the next level of necessary conditions, three conditions which correspond in a well-deened way to minimally non-ideal binary clutters. We characterize the subclass of matroids where the presen...
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Branch-and-cut methods are exact algorithms for integer programming problems. They consist of a combination of a cutting plane method with a branch-and-bound algorithm. These methods work by solving a sequence of linear programming relaxations of the integer programming problem. Cutting plane methods improve the relaxation of the problem to more closely approximate the integer programming probl...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series B
سال: 2013
ISSN: 0095-8956
DOI: 10.1016/j.jctb.2012.11.002