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.github/workflows | ||
org.emoflon.ilp | ||
org.emoflon.ilp.dependencies | ||
org.emoflon.ilp.feature | ||
org.emoflon.ilp.tests | ||
org.emoflon.ilp.updatesite | ||
scripts | ||
.gitignore | ||
.project | ||
LICENSE | ||
pom.xml | ||
README.md |
eMoflon-ILP
The goal of this plug-in is to simplify the use of different ILP solvers in Eclipse projects. Therefore, the plug-in provides an interface to specify the ILP problem only once instead of having to do different implementations for each solver individually. Switching between solvers is done by changing one parameter in the solver configuration.
How to install the plug-in
- Install at least one of the supported ILP solvers:
- Build + install the project to the local
.m2/
folder:
$ mvn clean install
How to build the plugin
- Install at least one of the supported ILP solvers:
- Build the project + feature + update site:
$ mvn clean package
How to run tests
Remember: Depending on the solver a license is necessary (e.g., for Gurobi).
- Run all tests:
$ mvn clean verify
- Run a specific test class (e.g., GlpkTest.java):
$ mvn -Dtest=GlpkTest -DfailIfNoTests=false verify
Before running tests with the CPLEX solver, it might be necessary to add the following Run Configuration to the VM Arguments (Eclipse: right click on the project -> Run as
-> Run Configurations
-> Arguments
tab), replace with the appropriate path, for example:
-Djava.library.path=/opt/ibm/ILOG/CPLEX_Studio2211/cplex/bin/x86-64_linux
Example Problem
Knapsack Problem
This example can be found in the test class SolverTest.java.
There is a set of items, which all have a weight and a value. The goal is to determine a collection of items, for which the profit is maximized but the capacity constraint is satisfied.
// Amount of items
int I = 6;
// Profit
int[] p = { 10, 13, 18, 32, 7, 15 };
// Weight
int[] w = { 11, 15, 20, 35, 10, 33 };
// Capacity
int c = 47;
// Create variables:
// 0 -> item i not put in knapsack
// 1 -> item i put in knapsack
List<BinaryVariable> x_i = new ArrayList<>();
for (int i = 0; i < I; i++) {
x_i.add(new BinaryVariable("x_" + i));
}
// Objective: maximize the total price of selected items
// maximize SUM(p_i * x_i)
Problem problem = new Problem();
problem.setType(ObjectiveType.MAX);
LinearFunction lin = new LinearFunction();
for (int i = 0; i < I; i++) {
lin.addTerm(x_i.get(i), p[i]);
}
// Constraint: Total weight must be equal or less than the capacity
// SUM(w_i * x_i) <= c
LinearConstraint c1 = new LinearConstraint(Operator.LESS_OR_EQUAL, c);
for (int i = 0; i < I; i++) {
c1.addTerm(x_i.get(i), w[i]);
}
// Model
problem.setObjective(lin);
problem.add(c1);
// Optimize
SolverConfig config = new SolverConfig(SolverType.GLPK, false, 0.0, true, 42, false, 0.0, false, 0, 0, true, false, false, null);
Solver solver = (new SolverHelper(config)).getSolver();
solver.buildILPProblem(problem);
SolverOutput out = solver.solve();
// Prints the result of the objective
System.out.println(out.toString());
// Sets the values for the Variables
solver.updateValuesFromSolution();
// Do something, e.g. print
solver.terminate();
Repository/Project structure
Name | Description |
---|---|
org.emoflon.ilp |
Contains the implementation of the plug-in. |
org.emoflon.ilp.feature |
Contains the information for the feature to export. |
org.emoflon.ilp.updatesite |
Contains the update site configuration (to include the feature above). |
org.emoflon.ilp.dependencies |
Contains all necessary dependencies (JARs of each solver). |
org.emoflon.ilp.tests |
Contains all tests and test-related content. |
ci.yml |
GitHub Actions configuration to build and test the plug-in. |
pom.xml |
Maven configuration file that contains the parent group/project. |
License
This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for more details.