Answers to: need help for bi-objective optimization with ILOG CPLEX for a distribution networkhttp://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network<p>hello,</p>
<p>I'm a beginner and I just started my thesis, I'm working on a bi-objective optimization ( cost +environmental impact) for a distribution network. I managed to model the objective functions but in order to run an optimization with ILOG CPLEX I need your help.
in my mathematical model I'm proposing two transport modes with two different costs, how can I process it in ILOG CPLEX ? all I find is tutorials for a network with one cost for transportation?</p>
<p>anyone can help and thank you in advance
( excuse my english)</p>enMon, 21 Mar 2016 15:38:41 -0400Answer by Paul Rubinhttp://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network/13480<p>I'm not sure I understand your question correctly, but if you are asking what I think you are asking, just create two sets of transportation variables, one for each mode, with different costs. Anywhere you would have used a single transportation variable (e.g., the volume of A moved from B to C), you now use a sum of two variables (volume of A moved B to C using mode 1 PLUS volume of A moved B to C using mode 2).</p>Paul RubinMon, 21 Mar 2016 15:38:41 -0400http://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network/13480Comment by Sune on Sune's answerhttp://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network#13452<p>You can take a look at this stuff: <a href="https://github.com/SuneGadegaard/TwoPhaseMethod">https://github.com/SuneGadegaard/TwoPhaseMethod</a> . I do not guarantee (but I hope) that it is bug-free! It is a simple straightforward implementation of a two-phase method that use CPLEX to solve the sub-problems arising. It should work for minimization problems.</p>SuneWed, 16 Mar 2016 05:59:25 -0400http://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network#13452Answer by Sunehttp://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network/13448<p>CPLEX is a single objective solver. If you want to solve bi-objective problems using CPLEX you need to implement a custom solver. Two popular choices for bi-objective problems are the \(\varepsilon\)-constraint method and two-phase methods.</p>SuneTue, 15 Mar 2016 14:49:08 -0400http://www.or-exchange.com/questions/13446/need-help-for-bi-objective-optimization-with-ilog-cplex-for-a-distribution-network/13448