Disjoint paths in sparse graphs ?
We generalize all the results obtained for maximum integer multiflow and minimum multicut problems in trees by Garg, Vazirani and Yannakakis [N. Garg, V.V. Vazirani, M. Yannakakis, Primal-dual approximation algorithms for integral flow and multicut in trees, Algorithmica 18 (1997) 320] to graphs with a fixed cyclomatic number, while this cannot be achieved for other classical generalizations of trees. We also introduce thek k -edge-outerplanar graphs, a class of planar graphs with arbitrary (but bounded) tree-width that generalizes the cacti, and show that the integrality gap of the maximum edge-disjoint paths problem is bounded in these graphs.
disjoint paths approximation algorithms planar graphs polynomial-time solvability bounded tree-width