Add qubo solver

qiskit/qubo/qubo_qiskit.py

@@ -0,0 +1,42 @@
+import copy
+import sys
+
+from qiskit.algorithms.minimum_eigensolvers import QAOA
+from qiskit.algorithms.optimizers import COBYLA
+from qiskit.primitives import Sampler
+from qiskit_optimization import QuadraticProgram
+from qiskit_optimization.algorithms import MinimumEigenOptimizer
+from qiskit_optimization.problems import VarType
+
+if len(sys.argv) != 3:
+    raise TypeError('This script expects exactly 2 arguments. Input file (argument 1) and output file (argument 2).')
+
+input_path = sys.argv[1]
+output_path = sys.argv[2]
+
+qp = QuadraticProgram()
+qp.read_from_lp_file(input_path)
+
+
+def relax_problem(problem):
+    """Change all variables to continuous."""
+    relaxed_problem = copy.deepcopy(problem)
+    for variable in relaxed_problem.variables:
+        variable.vartype = VarType.CONTINUOUS
+
+    return relaxed_problem
+
+qubo = qp
+# qubo = relax_problem(QuadraticProgramToQubo().convert(qp))
+# print(qp.prettyprint())
+
+qaoa_mes = QAOA(Sampler(), optimizer=COBYLA(), initial_point=[0.0, 1.0])
+
+qaoa = MinimumEigenOptimizer(qaoa_mes)
+
+qaoa_result = qaoa.solve(qubo)
+print(qaoa_result.prettyprint())
+
+f = open(output_path, 'w')
+f.write(qaoa_result.prettyprint())
+f.close()

qiskit/requirements.txt

@@ -5,5 +5,5 @@
 numpy
 pygmlparser
 qiskit == 0.44.*
-qiskit_optimization
+qiskit_optimization[cplex]
 qiskit-aer

src/main/java/edu/kit/provideq/toolbox/meta/ProblemType.java

@@ -4,6 +4,7 @@
 import edu.kit.provideq.toolbox.SolveRequest;
 import edu.kit.provideq.toolbox.featuremodel.SolveFeatureModelRequest;
 import edu.kit.provideq.toolbox.maxcut.SolveMaxCutRequest;
+import edu.kit.provideq.toolbox.qubo.SolveQuboRequest;
 import edu.kit.provideq.toolbox.sat.SolveSatRequest;
 
 /**
@@ -38,7 +39,14 @@ public enum ProblemType {
    * @see <a href="https://sdq.kastel.kit.edu/publications/pdfs/kowal2016b.pdf">
    *      "Explaining Anomalies in Feature Models", Kowal et al., 2026</a>
    */
-  FEATURE_MODEL_ANOMALY_VOID("feature-model-anomaly-void", SolveFeatureModelRequest.class);
+  FEATURE_MODEL_ANOMALY_VOID("feature-model-anomaly-void", SolveFeatureModelRequest.class),
+  /**
+   * QUBO (Quadratic Unconstrained Binary Optimization)
+   * A combinatorial optimization problem.
+   * For a given quadratic term with binary decision variables,
+   * find the minimal variable assignment of the term.
+   */
+  QUBO("qubo", SolveQuboRequest.class);
 
   private final String id;
   private final Class<? extends SolveRequest<?>> requestType;

src/main/java/edu/kit/provideq/toolbox/qubo/QuboMetaSolver.java

@@ -0,0 +1,44 @@
+package edu.kit.provideq.toolbox.qubo;
+
+import edu.kit.provideq.toolbox.meta.MetaSolver;
+import edu.kit.provideq.toolbox.meta.Problem;
+import edu.kit.provideq.toolbox.meta.ProblemType;
+import edu.kit.provideq.toolbox.meta.setting.MetaSolverSetting;
+import edu.kit.provideq.toolbox.qubo.solvers.QiskitQuboSolver;
+import edu.kit.provideq.toolbox.qubo.solvers.QuboSolver;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+/**
+ * Simple {@link MetaSolver} for MaxCut problems.
+ */
+@Component
+public class QuboMetaSolver extends MetaSolver<String, String, QuboSolver> {
+
+  @Autowired
+  public QuboMetaSolver(QiskitQuboSolver qiskitQuboSolver) {
+    super(ProblemType.QUBO, qiskitQuboSolver);
+  }
+
+  @Override
+  public QuboSolver findSolver(
+          Problem<String> problem,
+          List<MetaSolverSetting> metaSolverSettings) {
+    return (new ArrayList<>(this.solvers)).get((new Random()).nextInt(this.solvers.size()));
+  }
+
+  @Override
+  public List<String> getExampleProblems() {
+    return List.of("""
+        Maximize
+          3x + y
+        Subject To
+        Binary
+          x y
+        End
+        """);
+  }
+}

src/main/java/edu/kit/provideq/toolbox/qubo/SolveQuboRequest.java

@@ -0,0 +1,11 @@
+package edu.kit.provideq.toolbox.qubo;
+
+import edu.kit.provideq.toolbox.SolveRequest;
+
+/**
+ * POST Requests to /solve/qubo should have a response body of this form.
+ * The needed formula the qubo formula to solve in the
+ * <a href="https://www.gurobi.com/documentation/current/refman/lp_format.html">LP format</a>.
+ */
+public class SolveQuboRequest extends SolveRequest<String> {
+}

src/main/java/edu/kit/provideq/toolbox/qubo/solvers/QiskitQuboSolver.java

@@ -0,0 +1,60 @@
+package edu.kit.provideq.toolbox.qubo.solvers;
+
+import edu.kit.provideq.toolbox.PythonProcessRunner;
+import edu.kit.provideq.toolbox.Solution;
+import edu.kit.provideq.toolbox.SubRoutinePool;
+import edu.kit.provideq.toolbox.meta.Problem;
+import edu.kit.provideq.toolbox.meta.ProblemType;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.ApplicationContext;
+import org.springframework.stereotype.Component;
+
+@Component
+public class QiskitQuboSolver extends QuboSolver {
+  private final String quboPath;
+  private final ApplicationContext context;
+
+  @Autowired
+  public QiskitQuboSolver(
+      @Value("${qiskit.directory.qubo}") String quboPath,
+      ApplicationContext context) {
+    this.quboPath = quboPath;
+    this.context = context;
+  }
+
+  @Override
+  public String getName() {
+    return "Qiskit Qubo";
+  }
+
+  @Override
+  public boolean canSolve(Problem<String> problem) {
+    return problem.type() == ProblemType.QUBO;
+  }
+
+  @Override
+  public void solve(Problem<String> problem, Solution<String> solution,
+                    SubRoutinePool subRoutinePool) {
+    // Run Qiskit solver via console
+    var processResult = context
+        .getBean(
+            PythonProcessRunner.class,
+            quboPath,
+            "qubo_qiskit.py")
+        .addProblemFilePathToProcessCommand()
+        .addSolutionFilePathToProcessCommand()
+        .problemFileName("problem.lp")
+        .run(problem.type(), solution.getId(), problem.problemData());
+
+    // Return if process failed
+    if (!processResult.success()) {
+      solution.setDebugData(processResult.output());
+      solution.abort();
+      return;
+    }
+
+    solution.setSolutionData(processResult.output());
+    solution.complete();
+  }
+}

src/main/java/edu/kit/provideq/toolbox/qubo/solvers/QuboSolver.java

@@ -0,0 +1,6 @@
+package edu.kit.provideq.toolbox.qubo.solvers;
+
+import edu.kit.provideq.toolbox.meta.ProblemSolver;
+
+public abstract class QuboSolver implements ProblemSolver<String, String> {
+}

src/main/resources/application.properties

@@ -6,6 +6,7 @@ gams.directory.sat=${gams.directory}/sat
 
 qiskit.directory=qiskit
 qiskit.directory.max-cut=${qiskit.directory}/max-cut
+qiskit.directory.qubo=${qiskit.directory}/qubo
 
 cirq.directory=cirq
 cirq.directory.max-cut=${cirq.directory}/max-cut