“…Examples include trees [24], block graphs [18], series-parallel graphs [26], bipartite permutation graphs, and co-triangulated graphs [29]. Various approximation algorithms for MMM and MWMM have been proposed in the literature (see for instance [4,9,13,14,16,23,28]). Another line of research on MMM and MWMM considers the development of exponential time exact combinatorial algorithms [12,32].…”