The Minimum Vulnerability Problem

Sepehr Assadi, Ehsan Emamjomeh-Zadeh, Ashkan Norouzi-Fard, Sadra Yazdanbod, Hamid Zarrabi-Zadeh
2014 Algorithmica  
We revisit the problem of finding k paths with a minimum number of shared edges between two vertices of a graph. An edge is called shared if it is used in more than one of the k paths. We provide a ⌊k/2⌋-approximation algorithm for this problem, improving the best previous approximation factor of k − 1. We also provide the first approximation algorithm for the problem with a sublinear approximation factor of O(n 3/4 ), where n is the number of vertices in the input graph. For sparse graphs,
more » ... as bounded-degree and planar graphs, we show that the approximation factor of our algorithm can be improved to O( √ n). While the problem is NP-hard, and even hard to approximate to within an O(log n) factor, we show that the problem is polynomially solvable when k is a constant. This settles an open problem posed by Omran et al. regarding the complexity of the problem for small values of k. We present most of our results in a more general form where each edge of the graph has a sharing cost and a sharing capacity, and there is vulnerability parameter r that determines the number of times an edge can be used among different paths before it is counted as a shared/vulnerable edge.
doi:10.1007/s00453-014-9927-z fatcat:q64tdoecxfbhzhx7xdf7ymtbli