Search found 31 matches

by abb.omidi
2 months ago
Forum: Modeling
Topic: Issue on executing an option file
Replies: 0
Views: 732

Issue on executing an option file

Dear community team, I am trying to solve an NLP problem by using Baron solver via the Neos interface in the GAMS v.34. The option file contains two local parameters of the Baron solver and is as follows: option nlp= Baron; $onecho > baron.opt numloc 0 dolocal 0 $offecho model.optfile=1; When I have...
by abb.omidi
4 months ago
Forum: Modeling
Topic: Defining the planning horizon in the RCPSP
Replies: 0
Views: 835

Defining the planning horizon in the RCPSP

Dear support team, I am trying to write an optimization model related to the resource-constrained project schedule based on Pritsker et al. formulation. The model is as follows: test.jpg When I have defined the objective function as shown in the model, the final solution is incorrect but, when I wri...
by abb.omidi
5 months ago
Forum: Modeling
Topic: Issue with the reformulating MINLP
Replies: 0
Views: 756

Issue with the reformulating MINLP

Dear support team, I have tried to solve an optimization problem (an MINLP) to minimize the number of items that need to be stored. The objective function is as follows: objective function: Minimize z = sum(i, R(i)/x(i)) Where, R(i), i in {1, ..., n}, given constant and x(i) are integer variables. I...
by abb.omidi
1 year ago
Forum: Modeling
Topic: Solving MIP using MCP
Replies: 0
Views: 878

Solving MIP using MCP

Dear community team, I'm trying to solve a BIP using MCP solver. When I run the problem I have the following issue: Discrete variables can only appear in MIP, RMIP, MINLP, RMINLP, MIQCP or RMIQCP MPEC RMPEC problems. I was wondering if, A) Is it possible to use MCP solver for BIP/MIP? B) I'm trying ...
by abb.omidi
1 year ago
Forum: Modeling
Topic: Implementing decomposition method
Replies: 2
Views: 776

Re: Implementing decomposition method

Dear Dr Bussieck,

Many thanks for your suggestion.
As I'm not any experience in the graph colouring and I am interested in scheduling model, I'm wondering if, are there any related materials for the scheduling problems?

Regards
Omidi
by abb.omidi
1 year ago
Forum: Modeling
Topic: Implementing decomposition method
Replies: 2
Views: 776

Implementing decomposition method

Dear support team, I have often used GAMS and now have tried to implement a Dantzig-Wolfe Decomposition for an LP problem. It works fine for a small instance. Now, I'm trying to extend the DW-based algorithm to solve the MIP model. I'm aware that some of the algorithms like heuristic-based CG, can b...
by abb.omidi
1 year ago
Forum: Modeling
Topic: GAMS Kestrel Issue
Replies: 3
Views: 1703

Re: GAMS Kestrel Issue

Dear Dr Bussieck, Many thanks for your detailed explanations. The issue was fixed and the model was solved by the kestrel. I have another issue and I was wondering if, you could advise me about that. I have tried to solve a scheduling problem and regard to, the model is a large scale, I would like t...
by abb.omidi
1 year ago
Forum: Modeling
Topic: GAMS Kestrel Issue
Replies: 3
Views: 1703

GAMS Kestrel Issue

Dear support team, I tried to use GAMS and Kestrel a while and it worked fine. Recently, I downloaded the new GAMS version (30.1.0 re01a340 WEX-WEI x86 64bit/MS Windows) and I activated it by using a trial licence. Now, I'm trying to solve an optimization model using GAMS/Kestrel. When I run the GAM...
by abb.omidi
1 year ago
Forum: Modeling
Topic: Special constraint formulation
Replies: 0
Views: 1175

Special constraint formulation

Hello community team, I have tried to write a scheduling problem which has been described by Sousa and Wolsey in machine scheduling. I'm going to use two different approaches to write my code. First, using the special syntax into the constraint and second, create dynamic sets. The following code des...
by abb.omidi
1 year ago
Forum: Modeling
Topic: How to execute a warm start using GAMS/Cplex
Replies: 0
Views: 1146

How to execute a warm start using GAMS/Cplex

Dear community team, I have tried to solve a scheduling model. I would like to use a warm start to solve my problem because The model takes much time to solve optimally even for a small set of given data. The model statistic and what I'm looking for are as follows. The original model, a small instan...