Questions Tagged With hub-locationhttp://www.or-exchange.com/tags/hub-location/?type=rssquestions tagged <span class="tag">hub-location</span>enFri, 23 Feb 2018 19:46:12 -0500Cannot obtain the results from the hub location literature using CPLEXhttp://www.or-exchange.com/questions/15443/cannot-obtain-the-results-from-the-hub-location-literature-using-cplex<p>I have wrote the .mod file for the Single Allocation Hub Location Problem, following the mathematical program given in this paper: </p>
<blockquote>
<p>Skorin-Kapov D, Skorin-Kapov J,
O'Kelly M (1996) Tight linear
programming relaxations of
uncapacitated p-hub median problems.
European Journal of Operational
Research 94 (1996) 582-593</p>
</blockquote>
<p>Somehow I can not obtain the results provided by the authors. I am doing something wrong, but I can not find out what I am doing wrong. </p>
<pre><code>// nodes
int n = ...;
range N = 0..n-1;
// direct-line transport cost
float directTransportCost[N][N] = ...;
// discount coefficient
float alpha = ...;
// demand
float w[N][N] = ...;
// transport cost
float c[i in N][j in N][k in N][m in N] =
directTransportCost[i][k] + alpha * directTransportCost[k][m] + directTransportCost[m][j];
// decision variables
dvar boolean z[N][N];
dvar float+ x[N][N][N][N];
// cost minimization objective
minimize
(sum(i in N, j in N, k in N, m in N) w[i][j] * c[i][j][k][m] * x[i][j][k][m]);
subject to {
// number of hubs
// ctNumberOfHubs:
sum(k in N) z[k][k] == 4; // Inconsistency is observed not only for 4 hubs, but for every given number of hubs
// single allocation
forall(i in N)
//ctSingleAllocation:
sum(k in N) z[i][k] == 1;
// allocation to hub
forall(i in N, k in N)
//ctAllocation2Hub:
z[i][k] <= z[k][k];
// allocation of flow from origin
forall(i in N, j in N, k in N)
//ctOriginFlowAllocation:
sum(m in N) x[i][j][k][m] == z[i][k];
// allocation of flow to destination
forall(i in N, j in N, m in N)
//ctDestinationFlowAllocation:
sum(k in N) x[i][j][k][m] == z[j][m];
}
</code></pre>DDChFri, 23 Feb 2018 19:46:12 -0500http://www.or-exchange.com/questions/15443/cannot-obtain-the-results-from-the-hub-location-literature-using-cplexoplhub-locationcplexComputing Cost Matrix for the Hub Location Problemhttp://www.or-exchange.com/questions/7877/computing-cost-matrix-for-the-hub-location-problem<p>Dear all,</p>
<p>How can I compute the cost of traveling shipments between nodes in a hub location problem using distances of nodes? Is there any measure to use? How can I manage it?</p>nadiaThu, 25 Apr 2013 05:10:52 -0400http://www.or-exchange.com/questions/7877/computing-cost-matrix-for-the-hub-location-problemhub-locationfacility-locationlocation