| Popis: |
Given an undirected connected graph G = ( V , E ) , the minimum linear arrangement problem (MinLA) consists in determining a permutation π ≔ ( π 1 , … , π n ) of the node-set V = { 1 , … , n } , which minimizes the sum of edge costs | π i − π j | over all edges { i , j } ∈ E . We introduce a compact quadratic formulation, prove its correctness, and generate new mixed-integer linear formulations that require a very small number of variables and constraints. The idea behind the way we model permutations allows the development of strong valid constraints to strengthen the new formulations. We also adapt some cutting plane procedures from the literature to one of the new models. Computational experiments with benchmark and new instances are very encouraging and improve state-of-the-art solution approaches from the literature. |
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