FAST DETERMINISTIC PARALLEL BRANCH-AND-BOUND
Kieran T. Herley, Andrea Pietracaprina, Geppino Pucci · Parallel Processing Letters · 1999
The branch-and-bound problem involves determining the minimum cost leaf in a cost-labelled tree, subject to the constraint that only the root is known initially and that children are revealed only by visiting thier parent. We present the first efficient deterministic algorithm to solve the branch-and-bound problem for a tree T of constant degree on a p-processor parallel machine. Let c* be the cost of the minimum-cost leaf in T, and let n and h be the number of nodes and the height, respectively, of the subtree T* ⊆ T of nodes of cost less than or equal to c*. Our algorithm runs in O(n/p + h log 2(np)) time on an EREW-PRAM. Moreover, the running time faithfully reflects both communication and computation costs, unlike most of the previous results where the cost of local computation is ignored. For large ranges of the parameters, our algorithm matches the optimal performance of existing randomized strategies. The algorithm can be ported to any architecture for which an efficient implementation of Parallel Priority Queues [PP91] is available.