highs-sys 1.14.2

#include "HCheckConfig.h"
#include "Highs.h"
#include "SpecialLps.h"
#include "catch.hpp"

const bool dev_run = false;

bool doubleEqual(const double v0, const double v1) {
  return std::fabs(v0 - v1) < 1e-8;
}

void presolveSolvePostsolve(const std::string& model_file,
                            const bool solve_relaxation = false);

TEST_CASE("presolve-solve-postsolve-lp", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/25fv47.mps";
  presolveSolvePostsolve(model_file);
}

TEST_CASE("postsolve-no-basis", "[highs_test_presolve]") {
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/afiro.mps";
  highs.readModel(model_file);
  highs.run();
  const double objective_function_value =
      highs.getInfo().objective_function_value;
  highs.clearSolver();
  highs.presolve();
  HighsLp presolved_lp = highs.getPresolvedLp();
  Highs highs1;
  highs1.setOptionValue("output_flag", dev_run);
  if (dev_run)
    printf("presolved_lp.integrality_.size() = %d\n",
           int(presolved_lp.integrality_.size()));
  presolved_lp.integrality_.clear();
  highs1.setOptionValue("presolve", kHighsOffString);
  highs1.passModel(presolved_lp);
  highs1.run();
  HighsSolution solution = highs1.getSolution();
  HighsStatus status;
  for (HighsInt k = 0; k < 2; k++) {
    if (dev_run)
      printf(
          "Calling highs.postsolve(solution) with solution.col_value.size() = "
          "%d solution.col_dual.size() = %d\n",
          int(solution.col_value.size()), int(solution.col_dual.size()));
    status = highs.postsolve(solution);
    if (k == 0) {
      // With dual values, optimality can be identified
      REQUIRE(status == HighsStatus::kOk);
      REQUIRE(highs.getModelStatus() == HighsModelStatus::kOptimal);
    } else {
      // Without dual values, optimality can't be identified
      REQUIRE(status == HighsStatus::kWarning);
      REQUIRE(highs.getModelStatus() == HighsModelStatus::kUnknown);
    }
    REQUIRE(std::fabs(highs.getInfo().objective_function_value -
                      objective_function_value) <=
            1e-8 * std::max(1.0, std::fabs(objective_function_value)));
    // Compare the primal solution for the reduced and original problem
    HighsSolution postsolve_solution = highs.getSolution();
    const HighsInt* original_col_indices = highs.getPresolveOrigColsIndex();
    //    const HighsInt* original_row_indices =
    //    highs.getPresolveOrigRowsIndex();
    if (dev_run)
      printf(
          "Presolved model   Original model\n"
          "Col      Primal  Col      Primal\n");
    for (HighsInt iCol = 0; iCol < presolved_lp.num_col_; iCol++) {
      HighsInt original_iCol = original_col_indices[iCol];
      if (dev_run)
        printf("%3d %11.5g  %3d %11.5g\n", int(iCol), solution.col_value[iCol],
               int(original_iCol), postsolve_solution.col_value[original_iCol]);
      REQUIRE(doubleEqual(solution.col_value[iCol],
                          postsolve_solution.col_value[original_iCol]));
    }
    solution.dual_valid = false;
    solution.col_dual.clear();
    solution.row_dual.clear();
  }

  highs.resetGlobalScheduler(true);
}

TEST_CASE("presolve-solve-postsolve-mip", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/flugpl.mps";
  presolveSolvePostsolve(model_file);
}

TEST_CASE("presolve-solve-postsolve-relaxation", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/flugpl.mps";
  presolveSolvePostsolve(model_file, true);
}

TEST_CASE("presolve", "[highs_test_presolve]") {
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);

  // Make sure that an empty LP returns kNotReduced
  const HighsModel& presolved_model = highs.getPresolvedModel();
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kNotReduced);

  std::string model_file;
  model_file = std::string(HIGHS_DIR) + "/check/instances/adlittle.mps";
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kReduced);
  REQUIRE(!presolved_model.isEmpty());

  model_file = std::string(HIGHS_DIR) + "/check/instances/gas11.mps";
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() ==
          HighsPresolveStatus::kUnboundedOrInfeasible);
  REQUIRE(presolved_model.isEmpty());

  HighsLp lp;
  HighsModelStatus require_model_status;
  double optimal_objective;
  SpecialLps special_lps;

  special_lps.scipLpi3Lp(lp, require_model_status);
  highs.passModel(lp);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kInfeasible);
  REQUIRE(highs.getModelStatus() == require_model_status);
  REQUIRE(presolved_model.isEmpty());

  special_lps.distillationLp(lp, require_model_status, optimal_objective);
  // Have to set matrix dimensions to match presolved_model.lp_
  lp.setMatrixDimensions();
  highs.passModel(lp);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(lp.equalButForNames(presolved_model.lp_));
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kNotReduced);
  REQUIRE(highs.getModelStatus() == HighsModelStatus::kNotset);
  REQUIRE(!presolved_model.isEmpty());

  special_lps.primalDualInfeasible1Lp(lp, require_model_status);
  highs.passModel(lp);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kInfeasible);
  REQUIRE(highs.getModelStatus() == HighsModelStatus::kInfeasible);
  REQUIRE(presolved_model.isEmpty());
}

TEST_CASE("empty-row", "[highs_test_presolve]") {
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsLp lp;
  lp.num_col_ = 3;
  lp.num_row_ = 1;
  lp.col_cost_ = {-7.0, -6.0, -5.0};
  lp.col_lower_ = {-73.0, -83.0, -94.0};
  lp.col_upper_ = {62.0, 96.0, 62.0};
  lp.row_lower_ = {-19.0};
  lp.row_upper_ = {11.0};
  lp.a_matrix_.format_ = MatrixFormat::kRowwise;
  lp.a_matrix_.start_ = {0, 0};
  // LP has empty constraint matrix so doesn't need to be presolved,
  // and shouldn't be since this would cause vacuous null pointer
  // operation in util/HighsMatrixSlice.h (see #1531)
  highs.passModel(lp);
  highs.run();
  const HighsSolution& solution = highs.getSolution();
  const HighsBasis& basis = highs.getBasis();
  REQUIRE(HighsInt(solution.row_value.size()) == lp.num_row_);
  REQUIRE(HighsInt(basis.row_status.size()) == lp.num_row_);

  highs.resetGlobalScheduler(true);
}

void presolveSolvePostsolve(const std::string& model_file,
                            const bool solve_relaxation) {
  Highs highs0;
  Highs highs1;
  highs0.setOptionValue("output_flag", dev_run);
  highs1.setOptionValue("output_flag", dev_run);
  HighsStatus return_status;
  highs0.readModel(model_file);
  highs0.setOptionValue("solve_relaxation", solve_relaxation);
  return_status = highs0.presolve();
  REQUIRE(return_status == HighsStatus::kOk);
  HighsPresolveStatus model_presolve_status = highs0.getModelPresolveStatus();
  if (model_presolve_status == HighsPresolveStatus::kTimeout) {
    if (dev_run)
      printf("Presolve timeout: return status = %d\n", (int)return_status);
  }
  HighsLp lp = highs0.getPresolvedLp();
  highs1.passModel(lp);
  highs1.setOptionValue("solve_relaxation", solve_relaxation);
  highs1.setOptionValue("presolve", kHighsOffString);
  highs1.run();
  HighsSolution solution = highs1.getSolution();
  const double objective_value = highs1.getInfo().objective_function_value;
  if (lp.isMip() && !solve_relaxation) {
    return_status = highs0.postsolve(solution);
    REQUIRE(return_status == HighsStatus::kWarning);
    HighsModelStatus model_status = highs0.getModelStatus();
    REQUIRE(model_status == HighsModelStatus::kUnknown);
    const double dl_objective_value =
        std::fabs(highs0.getInfo().objective_function_value - objective_value);
    REQUIRE(dl_objective_value < 1e-9);
    REQUIRE(highs0.getInfo().primal_solution_status == kSolutionStatusFeasible);
    double mip_feasibility_tolerance;
    highs0.getOptionValue("mip_feasibility_tolerance",
                          mip_feasibility_tolerance);
    REQUIRE(highs0.getInfo().max_integrality_violation <=
            mip_feasibility_tolerance);
  } else {
    HighsBasis basis = highs1.getBasis();
    REQUIRE(basis.valid);
    return_status = highs0.postsolve(solution, basis);
    REQUIRE(return_status == HighsStatus::kOk);
    HighsModelStatus model_status = highs0.getModelStatus();
    REQUIRE(model_status == HighsModelStatus::kOptimal);
    REQUIRE(highs0.getInfo().simplex_iteration_count <= 0);
  }

  highs1.resetGlobalScheduler(true);
}

HighsStatus zeroCostColSing() {
  HighsLp lp;
  lp.num_col_ = 2;
  lp.num_row_ = 1;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(1);
  lp.a_matrix_.start_.push_back(2);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.value_.push_back(0.5);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.value_.push_back(0.5);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.row_lower_.push_back(0.1);
  lp.row_upper_.push_back(0.9);

  lp.col_cost_.push_back(0);
  lp.col_cost_.push_back(1);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

// handled by doubleton equality
HighsStatus colSingDoubletonEquality() {
  HighsLp lp;
  lp.num_col_ = 4;
  lp.num_row_ = 2;

  lp.a_matrix_.format_ = MatrixFormat::kColwise;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(2);
  lp.a_matrix_.start_.push_back(3);
  lp.a_matrix_.start_.push_back(4);
  lp.a_matrix_.start_.push_back(5);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(1);
  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(1);
  lp.a_matrix_.index_.push_back(1);

  lp.a_matrix_.value_.push_back(0.5);
  lp.a_matrix_.value_.push_back(0.5);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);
  lp.col_upper_.push_back(1);

  lp.row_lower_.push_back(1);
  lp.row_upper_.push_back(1);

  lp.row_lower_.push_back(0);
  lp.row_upper_.push_back(1);

  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(2);
  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(1);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

HighsStatus colSingDoubletonInequality() {
  HighsLp lp;
  lp.num_col_ = 4;
  lp.num_row_ = 2;

  lp.a_matrix_.format_ = MatrixFormat::kColwise;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(2);
  lp.a_matrix_.start_.push_back(3);
  lp.a_matrix_.start_.push_back(4);
  lp.a_matrix_.start_.push_back(5);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(1);
  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(1);
  lp.a_matrix_.index_.push_back(1);

  lp.a_matrix_.value_.push_back(0.5);
  lp.a_matrix_.value_.push_back(0.5);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);
  lp.col_upper_.push_back(1);

  lp.row_lower_.push_back(0);
  lp.row_upper_.push_back(1);

  lp.row_lower_.push_back(0);
  lp.row_upper_.push_back(1);

  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(2);
  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(1);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

// handled by doubleton equality
HighsStatus twoColSingDoubletonEquality() {
  HighsLp lp;
  lp.num_col_ = 2;
  lp.num_row_ = 1;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(1);
  lp.a_matrix_.start_.push_back(2);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(0);

  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.row_lower_.push_back(1);
  lp.row_upper_.push_back(1);

  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(2);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

// handled by special case.
HighsStatus twoColSingDoubletonInequality() {
  HighsLp lp;
  lp.num_col_ = 2;
  lp.num_row_ = 1;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(1);
  lp.a_matrix_.start_.push_back(2);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.index_.push_back(0);

  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.value_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.col_lower_.push_back(0);
  lp.col_upper_.push_back(1);

  lp.row_lower_.push_back(0);
  lp.row_upper_.push_back(1);

  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(2);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  highs.run();
  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

// No commas in test case name.
TEST_CASE("zero-cost", "[presolve-col-sing]") {
  if (dev_run) std::cout << "Presolve 1." << std::endl;
  HighsStatus status = zeroCostColSing();
  std::string str = highsStatusToString(status);
  CHECK(str == "OK");
}

TEST_CASE("col-sing-doubleton-eq", "[presolve-col-sing]") {
  if (dev_run) std::cout << "Presolve 2." << std::endl;
  HighsStatus status = colSingDoubletonEquality();
  std::string str = highsStatusToString(status);
  CHECK(str == "OK");
}

TEST_CASE("col-sing-doubleton-ineq", "[presolve-col-sing]") {
  if (dev_run) std::cout << "Presolve 3." << std::endl;
  HighsStatus status = colSingDoubletonInequality();
  std::string str = highsStatusToString(status);
  CHECK(str == "OK");
}

TEST_CASE("two-col-sing-doubleton-eq", "[presolve-col-sing]") {
  if (dev_run) std::cout << "Presolve 4." << std::endl;
  HighsStatus status = twoColSingDoubletonEquality();
  std::string str = highsStatusToString(status);
  CHECK(str == "OK");
}

TEST_CASE("two-col-sing-doubleton-ineq", "[presolve-col-sing]") {
  if (dev_run) std::cout << "Presolve 5." << std::endl;
  HighsStatus status = twoColSingDoubletonInequality();
  std::string str = highsStatusToString(status);
  REQUIRE(str == "OK");
}

// test case failing
HighsStatus issue425() {
  HighsLp lp;
  lp.num_col_ = 4;
  lp.num_row_ = 4;

  lp.a_matrix_.start_.push_back(0);
  lp.a_matrix_.start_.push_back(3);
  lp.a_matrix_.start_.push_back(5);
  lp.a_matrix_.start_.push_back(6);
  lp.a_matrix_.start_.push_back(7);

  lp.a_matrix_.index_.push_back(0);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.index_.push_back(2);
  lp.a_matrix_.value_.push_back(1);
  lp.a_matrix_.index_.push_back(3);
  lp.a_matrix_.value_.push_back(1);

  lp.a_matrix_.index_.push_back(1);
  lp.a_matrix_.value_.push_back(2);
  lp.a_matrix_.index_.push_back(3);
  lp.a_matrix_.value_.push_back(1);

  lp.a_matrix_.index_.push_back(3);
  lp.a_matrix_.value_.push_back(1);

  lp.a_matrix_.index_.push_back(3);
  lp.a_matrix_.value_.push_back(1);

  lp.col_lower_.assign(lp.num_col_, 0);
  lp.col_upper_.assign(lp.num_col_, kHighsInf);

  std::vector<double> b{1, 2, 2, 4};
  lp.row_lower_ = b;
  lp.row_upper_ = b;

  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(1);
  lp.col_cost_.push_back(2);

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  HighsStatus status = highs.passModel(lp);
  assert(status == HighsStatus::kOk);

  status = highs.run();

  highs.resetGlobalScheduler(true);

  return status;
}

TEST_CASE("presolve-issue-425", "[highs_test_presolve]") {
  if (dev_run) {
    std::cout << std::endl;
    std::cout << "Presolve issue 425." << std::endl;
  }
  HighsStatus status = issue425();
  REQUIRE(status == HighsStatus::kOk);
}

TEST_CASE("postsolve-reduced-to-empty", "[highs_test_presolve]") {
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  // Read MIP model "egout"
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/egout.mps";
  highs.readModel(model_file);

  // Turn into LP
  std::vector<HighsInt> vars(highs.getNumCol(), 1);
  std::vector<HighsVarType> integral(highs.getNumCol(),
                                     HighsVarType::kContinuous);
  highs.changeColsIntegrality(vars.data(), integral.data());

  // Presolve
  HighsStatus presolveStatus = highs.presolve();
  REQUIRE(presolveStatus == HighsStatus::kOk);

  // Presolve reduced the problem to empty
  REQUIRE(highs.getModelPresolveStatus() ==
          HighsPresolveStatus::kReducedToEmpty);

  // Set up empty solution
  HighsSolution hsol = HighsSolution();
  hsol.value_valid = true;
  hsol.dual_valid = true;

  // Postsolve solution
  HighsStatus postsolveStatus = highs.postsolve(hsol);
  REQUIRE(postsolveStatus == HighsStatus::kOk);

  // Postsolved solution should be feasible / optimal
  REQUIRE(highs.getModelStatus() == HighsModelStatus::kOptimal);
  REQUIRE(highs.getInfo().num_primal_infeasibilities == 0);
  REQUIRE(highs.getInfo().num_dual_infeasibilities == 0);
}

TEST_CASE("write-presolved-model", "[highs_test_presolve]") {
  const std::string test_name = Catch::getResultCapture().getCurrentTestName();
  const std::string presolved_model_file = test_name + ".mps";
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/afiro.mps";
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  REQUIRE(highs.readModel(model_file) == HighsStatus::kOk);
  highs.presolve();
  highs.writePresolvedModel(presolved_model_file);
  // Read and solve the presolved model using a new Highs instance
  Highs highs1;
  highs1.setOptionValue("output_flag", dev_run);
  highs1.readModel(presolved_model_file);
  highs1.run();
  // Extract the optimal solution and basis
  HighsSolution solution = highs1.getSolution();
  HighsBasis basis = highs1.getBasis();
  // Perform postsolve using the optimal solution and basis for the
  // presolved model
  highs.postsolve(solution, basis);
  // The solution should be optimal, so no solver is run, and
  // simplex_iteration_count is -1
  REQUIRE(highs.getInfo().simplex_iteration_count == -1);
  std::remove(presolved_model_file.c_str());

  highs1.resetGlobalScheduler(true);
}

TEST_CASE("presolve-slacks", "[highs_test_presolve]") {
  // This LP reduces to empty, because the equation is a doubleton
  HighsLp lp;
  lp.num_col_ = 2;
  lp.num_row_ = 1;
  lp.col_cost_ = {1, 0};
  lp.col_lower_ = {0, 0};
  lp.col_upper_ = {kHighsInf, kHighsInf};
  lp.row_lower_ = {1};
  lp.row_upper_ = {1};
  lp.a_matrix_.start_ = {0, 1, 2};
  lp.a_matrix_.index_ = {0, 0};
  lp.a_matrix_.value_ = {1, 1};
  Highs h;
  h.setOptionValue("output_flag", dev_run);
  REQUIRE(h.passModel(lp) == HighsStatus::kOk);
  REQUIRE(h.presolve() == HighsStatus::kOk);
  REQUIRE(h.getPresolvedLp().num_col_ == 0);
  REQUIRE(h.getPresolvedLp().num_row_ == 0);

  lp.num_col_ = 4;
  lp.num_row_ = 2;
  lp.col_cost_ = {-10, -25, 0, 0};
  lp.col_lower_ = {0, 0, 0, 0};
  lp.col_upper_ = {kHighsInf, kHighsInf, kHighsInf, kHighsInf};
  lp.row_lower_ = {80, 120};
  lp.row_upper_ = {80, 120};
  lp.a_matrix_.start_ = {0, 2, 4, 5, 6};
  lp.a_matrix_.index_ = {0, 1, 0, 1, 0, 1};
  lp.a_matrix_.value_ = {1, 1, 2, 4, 1, 1};
  REQUIRE(h.setOptionValue("presolve_remove_slacks", true) == HighsStatus::kOk);
  REQUIRE(h.passModel(lp) == HighsStatus::kOk);
  REQUIRE(h.run() == HighsStatus::kOk);
  REQUIRE(h.presolve() == HighsStatus::kOk);
  REQUIRE(h.getPresolvedLp().num_col_ == 2);
  REQUIRE(h.getPresolvedLp().num_row_ == 2);

  h.resetGlobalScheduler(true);
}

TEST_CASE("presolve-issue-2095", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/issue-2095.mps";
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kReduced);
}

TEST_CASE("presolve-only-at-root", "[highs_test_presolve]") {
  std::string model_file = std::string(HIGHS_DIR) + "/check/instances/rgn.mps";

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  // Allow only presolve at root node
  highs.setOptionValue("mip_root_presolve_only", true);
  highs.readModel(model_file);
  REQUIRE(highs.run() == HighsStatus::kOk);

  highs.resetGlobalScheduler(true);
}

TEST_CASE("lifting-for-probing", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/gesa2.mps";

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  // Enable lifting for probing
  highs.setOptionValue("mip_lifting_for_probing", 1);
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
}

TEST_CASE("presolve-issue-2388", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/issue-2388.lp";
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() ==
          HighsPresolveStatus::kReducedToEmpty);
}

TEST_CASE("presolve-issue-2402", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/issue-2402.mps";
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kInfeasible);
}

TEST_CASE("presolve-issue-2446", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/issue-2446.mps";
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  highs.readModel(model_file);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
  REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kReduced);
}

TEST_CASE("presolve-solve-postsolve-no-col-dual", "[highs_test_presolve]") {
  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/afiro.mps";
  highs.readModel(model_file);
  highs.presolve();
  HighsLp presolved_lp = highs.getPresolvedLp();
  Highs highs1;
  highs1.setOptionValue("output_flag", dev_run);
  highs1.setOptionValue("presolve", kHighsOffString);
  highs1.passModel(presolved_lp);
  highs1.run();
  HighsSolution solution = highs1.getSolution();

  // Perform postsolve using the optimal solution and basis for the
  // presolved model
  REQUIRE(highs.postsolve(solution) == HighsStatus::kOk);

  // If row duals are supplied, then column duals must also be suppplied
  solution.col_dual.clear();
  REQUIRE(highs.postsolve(solution) == HighsStatus::kError);

  highs.resetGlobalScheduler(true);
}

TEST_CASE("presolve-egout-ac", "[highs_test_presolve]") {
  // Tests the case where, for this model when run_crossover is off,
  // sparsify is used to reduce the LP to empty. However, when
  // starting from an empty LP, basis postsolve is always used
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/egout-ac.mps";
  Highs h;
  h.setOptionValue("output_flag", dev_run);
  REQUIRE(h.setOptionValue("presolve_rule_logging", true) == HighsStatus::kOk);
  if (dev_run)
    REQUIRE(h.setOptionValue("log_dev_level", 1) == HighsStatus::kOk);
  REQUIRE(h.readModel(model_file) == HighsStatus::kOk);
  // Firstly check that pure presolve reduces the LP to empty
  REQUIRE(h.presolve() == HighsStatus::kOk);
  // Ensure that sparsify isn't called
  REQUIRE(h.getPresolveLog().rule[kPresolveRuleSparsify].call == 0);

  const HighsLp& presolved_lp = h.getPresolvedLp();
  REQUIRE(presolved_lp.num_col_ == 0);
  REQUIRE(presolved_lp.num_row_ == 0);

  HighsSolution solution;
  HighsBasis basis;
  basis.useful = true;
  solution.value_valid = true;
  solution.dual_valid = true;
  // Check that postsolve with the empty solution and basis runs OK -
  // ie doesn't trigger assert due to sparsify having been used
  REQUIRE(h.postsolve(solution, basis) == HighsStatus::kOk);

  // Check that using IPM with crossover runs OK without using
  // sparsify
  REQUIRE(h.setOptionValue("solver", kIpmString) == HighsStatus::kOk);
  REQUIRE(h.run() == HighsStatus::kOk);
  REQUIRE(h.getPresolveLog().rule[kPresolveRuleSparsify].call == 0);

  // Check that pure presolve reduces the LP to empty without using
  // sparsify
  REQUIRE(h.presolve() == HighsStatus::kOk);
  REQUIRE(h.getPresolveLog().rule[kPresolveRuleSparsify].call == 0);
  REQUIRE(h.postsolve(solution, basis) == HighsStatus::kOk);

  // Check that pure presolve reduces the LP to empty using sparsify
  // when lp_presolve_requires_basis_postsolve is false
  bool lp_presolve_requires_basis_postsolve = false;
  REQUIRE(h.setOptionValue("lp_presolve_requires_basis_postsolve",
                           lp_presolve_requires_basis_postsolve) ==
          HighsStatus::kOk);
  REQUIRE(h.presolve() == HighsStatus::kOk);
  REQUIRE(h.getPresolveLog().rule[kPresolveRuleSparsify].call > 0);
  REQUIRE(h.postsolve(solution, basis) == HighsStatus::kOk);
  REQUIRE(h.getOptions().lp_presolve_requires_basis_postsolve ==
          lp_presolve_requires_basis_postsolve);

  // Now, with crossover off
  REQUIRE(h.setOptionValue("run_crossover", kHighsOffString) ==
          HighsStatus::kOk);

  // Now reset lp_presolve_requires_basis_postsolve default to true,
  // to test whether it's set false due to running IPM without
  // crossover
  lp_presolve_requires_basis_postsolve = true;
  REQUIRE(h.setOptionValue("lp_presolve_requires_basis_postsolve",
                           lp_presolve_requires_basis_postsolve) ==
          HighsStatus::kOk);

  REQUIRE(h.clearSolver() == HighsStatus::kOk);
  REQUIRE(h.run() == HighsStatus::kOk);
  REQUIRE(h.getPresolveLog().rule[kPresolveRuleSparsify].call > 0);
  // Ensure that lp_presolve_requires_basis_postsolve has been reset
  // to true, after being set false before presolve when using IPM
  // without crossover
  REQUIRE(h.getOptions().lp_presolve_requires_basis_postsolve ==
          lp_presolve_requires_basis_postsolve);

  h.resetGlobalScheduler(true);
}

TEST_CASE("dual-bound-tightening", "[highs_test_presolve]") {
  std::string model_file =
      std::string(HIGHS_DIR) + "/check/instances/gesa2.mps";

  Highs highs;
  highs.setOptionValue("output_flag", dev_run);
  highs.readModel(model_file);

  // complement variables to get code coverage
  HighsLp lp = highs.getLp();
  std::transform(lp.a_matrix_.value_.begin(), lp.a_matrix_.value_.end(),
                 lp.a_matrix_.value_.begin(), [](double v) { return -v; });
  std::transform(lp.col_cost_.begin(), lp.col_cost_.end(), lp.col_cost_.begin(),
                 [](double v) { return -v; });
  std::transform(lp.col_upper_.begin(), lp.col_upper_.end(),
                 lp.col_upper_.begin(), [](double v) { return -v; });
  std::transform(lp.col_lower_.begin(), lp.col_lower_.end(),
                 lp.col_lower_.begin(), [](double v) { return -v; });
  std::swap(lp.col_lower_, lp.col_upper_);

  highs.passModel(lp);
  REQUIRE(highs.presolve() == HighsStatus::kOk);
}