llvm-project/mlir/unittests/Analysis/Presburger/SimplexTest.cpp

595 lines
22 KiB
C++

//===- SimplexTest.cpp - Tests for Simplex --------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Parser.h"
#include "Utils.h"
#include "mlir/Analysis/Presburger/Simplex.h"
#include "mlir/IR/MLIRContext.h"
#include <gmock/gmock.h>
#include <gtest/gtest.h>
using namespace mlir;
using namespace presburger;
/// Convenience functions to pass literals to Simplex.
void addInequality(SimplexBase &simplex, ArrayRef<int64_t> coeffs) {
simplex.addInequality(getMPIntVec(coeffs));
}
void addEquality(SimplexBase &simplex, ArrayRef<int64_t> coeffs) {
simplex.addEquality(getMPIntVec(coeffs));
}
bool isRedundantInequality(Simplex &simplex, ArrayRef<int64_t> coeffs) {
return simplex.isRedundantInequality(getMPIntVec(coeffs));
}
bool isRedundantInequality(LexSimplex &simplex, ArrayRef<int64_t> coeffs) {
return simplex.isRedundantInequality(getMPIntVec(coeffs));
}
bool isRedundantEquality(Simplex &simplex, ArrayRef<int64_t> coeffs) {
return simplex.isRedundantEquality(getMPIntVec(coeffs));
}
bool isSeparateInequality(LexSimplex &simplex, ArrayRef<int64_t> coeffs) {
return simplex.isSeparateInequality(getMPIntVec(coeffs));
}
Simplex::IneqType findIneqType(Simplex &simplex, ArrayRef<int64_t> coeffs) {
return simplex.findIneqType(getMPIntVec(coeffs));
}
/// Take a snapshot, add constraints making the set empty, and rollback.
/// The set should not be empty after rolling back. We add additional
/// constraints after the set is already empty and roll back the addition
/// of these. The set should be marked non-empty only once we rollback
/// past the addition of the first constraint that made it empty.
TEST(SimplexTest, emptyRollback) {
Simplex simplex(2);
// (u - v) >= 0
addInequality(simplex, {1, -1, 0});
ASSERT_FALSE(simplex.isEmpty());
unsigned snapshot = simplex.getSnapshot();
// (u - v) <= -1
addInequality(simplex, {-1, 1, -1});
ASSERT_TRUE(simplex.isEmpty());
unsigned snapshot2 = simplex.getSnapshot();
// (u - v) <= -3
addInequality(simplex, {-1, 1, -3});
ASSERT_TRUE(simplex.isEmpty());
simplex.rollback(snapshot2);
ASSERT_TRUE(simplex.isEmpty());
simplex.rollback(snapshot);
ASSERT_FALSE(simplex.isEmpty());
}
/// Check that the set gets marked as empty when we add contradictory
/// constraints.
TEST(SimplexTest, addEquality_separate) {
Simplex simplex(1);
addInequality(simplex, {1, -1}); // x >= 1.
ASSERT_FALSE(simplex.isEmpty());
addEquality(simplex, {1, 0}); // x == 0.
EXPECT_TRUE(simplex.isEmpty());
}
void expectInequalityMakesSetEmpty(Simplex &simplex, ArrayRef<int64_t> coeffs,
bool expect) {
ASSERT_FALSE(simplex.isEmpty());
unsigned snapshot = simplex.getSnapshot();
addInequality(simplex, coeffs);
EXPECT_EQ(simplex.isEmpty(), expect);
simplex.rollback(snapshot);
}
TEST(SimplexTest, addInequality_rollback) {
Simplex simplex(3);
SmallVector<int64_t, 4> coeffs[]{{1, 0, 0, 0}, // u >= 0.
{-1, 0, 0, 0}, // u <= 0.
{1, -1, 1, 0}, // u - v + w >= 0.
{1, 1, -1, 0}}; // u + v - w >= 0.
// The above constraints force u = 0 and v = w.
// The constraints below violate v = w.
SmallVector<int64_t, 4> checkCoeffs[]{{0, 1, -1, -1}, // v - w >= 1.
{0, -1, 1, -1}}; // v - w <= -1.
for (int run = 0; run < 4; run++) {
unsigned snapshot = simplex.getSnapshot();
expectInequalityMakesSetEmpty(simplex, checkCoeffs[0], false);
expectInequalityMakesSetEmpty(simplex, checkCoeffs[1], false);
for (int i = 0; i < 4; i++)
addInequality(simplex, coeffs[(run + i) % 4]);
expectInequalityMakesSetEmpty(simplex, checkCoeffs[0], true);
expectInequalityMakesSetEmpty(simplex, checkCoeffs[1], true);
simplex.rollback(snapshot);
EXPECT_EQ(simplex.getNumConstraints(), 0u);
expectInequalityMakesSetEmpty(simplex, checkCoeffs[0], false);
expectInequalityMakesSetEmpty(simplex, checkCoeffs[1], false);
}
}
Simplex simplexFromConstraints(unsigned nDim,
ArrayRef<SmallVector<int64_t, 8>> ineqs,
ArrayRef<SmallVector<int64_t, 8>> eqs) {
Simplex simplex(nDim);
for (const auto &ineq : ineqs)
addInequality(simplex, ineq);
for (const auto &eq : eqs)
addEquality(simplex, eq);
return simplex;
}
TEST(SimplexTest, isUnbounded) {
EXPECT_FALSE(simplexFromConstraints(
2, {{1, 1, 0}, {-1, -1, 0}, {1, -1, 5}, {-1, 1, -5}}, {})
.isUnbounded());
EXPECT_TRUE(
simplexFromConstraints(2, {{1, 1, 0}, {1, -1, 5}, {-1, 1, -5}}, {})
.isUnbounded());
EXPECT_TRUE(
simplexFromConstraints(2, {{-1, -1, 0}, {1, -1, 5}, {-1, 1, -5}}, {})
.isUnbounded());
EXPECT_TRUE(simplexFromConstraints(2, {}, {}).isUnbounded());
EXPECT_FALSE(simplexFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 0, -1},
{0, -2, 0, 1},
{0, 0, 2, -1},
{0, 0, -2, 1},
},
{})
.isUnbounded());
EXPECT_TRUE(simplexFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 0, -1},
{0, -2, 0, 1},
{0, 0, -2, 1},
},
{})
.isUnbounded());
EXPECT_TRUE(simplexFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 0, -1},
{0, -2, 0, 1},
{0, 0, 2, -1},
},
{})
.isUnbounded());
// Bounded set with equalities.
EXPECT_FALSE(simplexFromConstraints(2,
{{1, 1, 1}, // x + y >= -1.
{-1, -1, 1}}, // x + y <= 1.
{{1, -1, 0}} // x = y.
)
.isUnbounded());
// Unbounded set with equalities.
EXPECT_TRUE(simplexFromConstraints(3,
{{1, 1, 1, 1}, // x + y + z >= -1.
{-1, -1, -1, 1}}, // x + y + z <= 1.
{{1, -1, -1, 0}} // x = y + z.
)
.isUnbounded());
// Rational empty set.
EXPECT_FALSE(simplexFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 2, -1},
{0, -2, -2, 1},
{3, 3, 3, -4},
},
{})
.isUnbounded());
}
TEST(SimplexTest, getSamplePointIfIntegral) {
// Empty set.
EXPECT_FALSE(simplexFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 2, -1},
{0, -2, -2, 1},
{3, 3, 3, -4},
},
{})
.getSamplePointIfIntegral()
.has_value());
auto maybeSample = simplexFromConstraints(2,
{// x = y - 2.
{1, -1, 2},
{-1, 1, -2},
// x + y = 2.
{1, 1, -2},
{-1, -1, 2}},
{})
.getSamplePointIfIntegral();
EXPECT_TRUE(maybeSample.has_value());
EXPECT_THAT(*maybeSample, testing::ElementsAre(0, 2));
auto maybeSample2 = simplexFromConstraints(2,
{
{1, 0, 0}, // x >= 0.
{-1, 0, 0}, // x <= 0.
},
{
{0, 1, -2} // y = 2.
})
.getSamplePointIfIntegral();
EXPECT_TRUE(maybeSample2.has_value());
EXPECT_THAT(*maybeSample2, testing::ElementsAre(0, 2));
EXPECT_FALSE(simplexFromConstraints(1,
{// 2x = 1. (no integer solutions)
{2, -1},
{-2, +1}},
{})
.getSamplePointIfIntegral()
.has_value());
}
/// Some basic sanity checks involving zero or one variables.
TEST(SimplexTest, isMarkedRedundant_no_var_ge_zero) {
Simplex simplex(0);
addInequality(simplex, {0}); // 0 >= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_TRUE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_no_var_eq) {
Simplex simplex(0);
addEquality(simplex, {0}); // 0 == 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_TRUE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_pos_var_eq) {
Simplex simplex(1);
addEquality(simplex, {1, 0}); // x == 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_FALSE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_zero_var_eq) {
Simplex simplex(1);
addEquality(simplex, {0, 0}); // 0x == 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_TRUE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_neg_var_eq) {
Simplex simplex(1);
addEquality(simplex, {-1, 0}); // -x == 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_FALSE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_pos_var_ge) {
Simplex simplex(1);
addInequality(simplex, {1, 0}); // x >= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_FALSE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_zero_var_ge) {
Simplex simplex(1);
addInequality(simplex, {0, 0}); // 0x >= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_TRUE(simplex.isMarkedRedundant(0));
}
TEST(SimplexTest, isMarkedRedundant_neg_var_ge) {
Simplex simplex(1);
addInequality(simplex, {-1, 0}); // x <= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_FALSE(simplex.isMarkedRedundant(0));
}
/// None of the constraints are redundant. Slightly more complicated test
/// involving an equality.
TEST(SimplexTest, isMarkedRedundant_no_redundant) {
Simplex simplex(3);
addEquality(simplex, {-1, 0, 1, 0}); // u = w.
addInequality(simplex, {-1, 16, 0, 15}); // 15 - (u - 16v) >= 0.
addInequality(simplex, {1, -16, 0, 0}); // (u - 16v) >= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
for (unsigned i = 0; i < simplex.getNumConstraints(); ++i)
EXPECT_FALSE(simplex.isMarkedRedundant(i)) << "i = " << i << "\n";
}
TEST(SimplexTest, isMarkedRedundant_repeated_constraints) {
Simplex simplex(3);
// [4] to [7] are repeats of [0] to [3].
addInequality(simplex, {0, -1, 0, 1}); // [0]: y <= 1.
addInequality(simplex, {-1, 0, 8, 7}); // [1]: 8z >= x - 7.
addInequality(simplex, {1, 0, -8, 0}); // [2]: 8z <= x.
addInequality(simplex, {0, 1, 0, 0}); // [3]: y >= 0.
addInequality(simplex, {-1, 0, 8, 7}); // [4]: 8z >= 7 - x.
addInequality(simplex, {1, 0, -8, 0}); // [5]: 8z <= x.
addInequality(simplex, {0, 1, 0, 0}); // [6]: y >= 0.
addInequality(simplex, {0, -1, 0, 1}); // [7]: y <= 1.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_EQ(simplex.isMarkedRedundant(0), true);
EXPECT_EQ(simplex.isMarkedRedundant(1), true);
EXPECT_EQ(simplex.isMarkedRedundant(2), true);
EXPECT_EQ(simplex.isMarkedRedundant(3), true);
EXPECT_EQ(simplex.isMarkedRedundant(4), false);
EXPECT_EQ(simplex.isMarkedRedundant(5), false);
EXPECT_EQ(simplex.isMarkedRedundant(6), false);
EXPECT_EQ(simplex.isMarkedRedundant(7), false);
}
TEST(SimplexTest, isMarkedRedundant) {
Simplex simplex(3);
addInequality(simplex, {0, -1, 0, 1}); // [0]: y <= 1.
addInequality(simplex, {1, 0, 0, -1}); // [1]: x >= 1.
addInequality(simplex, {-1, 0, 0, 2}); // [2]: x <= 2.
addInequality(simplex, {-1, 0, 2, 7}); // [3]: 2z >= x - 7.
addInequality(simplex, {1, 0, -2, 0}); // [4]: 2z <= x.
addInequality(simplex, {0, 1, 0, 0}); // [5]: y >= 0.
addInequality(simplex, {0, 1, -2, 1}); // [6]: y >= 2z - 1.
addInequality(simplex, {-1, 1, 0, 1}); // [7]: y >= x - 1.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
// [0], [1], [3], [4], [7] together imply [2], [5], [6] must hold.
//
// From [7], [0]: x <= y + 1 <= 2, so we have [2].
// From [7], [1]: y >= x - 1 >= 0, so we have [5].
// From [4], [7]: 2z - 1 <= x - 1 <= y, so we have [6].
EXPECT_FALSE(simplex.isMarkedRedundant(0));
EXPECT_FALSE(simplex.isMarkedRedundant(1));
EXPECT_TRUE(simplex.isMarkedRedundant(2));
EXPECT_FALSE(simplex.isMarkedRedundant(3));
EXPECT_FALSE(simplex.isMarkedRedundant(4));
EXPECT_TRUE(simplex.isMarkedRedundant(5));
EXPECT_TRUE(simplex.isMarkedRedundant(6));
EXPECT_FALSE(simplex.isMarkedRedundant(7));
}
TEST(SimplexTest, isMarkedRedundantTiledLoopNestConstraints) {
Simplex simplex(3); // Variables are x, y, N.
addInequality(simplex, {1, 0, 0, 0}); // [0]: x >= 0.
addInequality(simplex, {-32, 0, 1, -1}); // [1]: 32x <= N - 1.
addInequality(simplex, {0, 1, 0, 0}); // [2]: y >= 0.
addInequality(simplex, {-32, 1, 0, 0}); // [3]: y >= 32x.
addInequality(simplex, {32, -1, 0, 31}); // [4]: y <= 32x + 31.
addInequality(simplex, {0, -1, 1, -1}); // [5]: y <= N - 1.
// [3] and [0] imply [2], as we have y >= 32x >= 0.
// [3] and [5] imply [1], as we have 32x <= y <= N - 1.
simplex.detectRedundant();
EXPECT_FALSE(simplex.isMarkedRedundant(0));
EXPECT_TRUE(simplex.isMarkedRedundant(1));
EXPECT_TRUE(simplex.isMarkedRedundant(2));
EXPECT_FALSE(simplex.isMarkedRedundant(3));
EXPECT_FALSE(simplex.isMarkedRedundant(4));
EXPECT_FALSE(simplex.isMarkedRedundant(5));
}
TEST(SimplexTest, pivotRedundantRegressionTest) {
Simplex simplex(2);
addInequality(simplex, {-1, 0, -1}); // x <= -1.
unsigned snapshot = simplex.getSnapshot();
addInequality(simplex, {-1, 0, -2}); // x <= -2.
addInequality(simplex, {-3, 0, -6});
// This first marks x <= -1 as redundant. Then it performs some more pivots
// to check if the other constraints are redundant. Pivot must update the
// non-redundant rows as well, otherwise these pivots result in an incorrect
// tableau state. In particular, after the rollback below, some rows that are
// NOT marked redundant will have an incorrect state.
simplex.detectRedundant();
// After the rollback, the only remaining constraint is x <= -1.
// The maximum value of x should be -1.
simplex.rollback(snapshot);
MaybeOptimum<Fraction> maxX =
simplex.computeOptimum(Simplex::Direction::Up, getMPIntVec({1, 0, 0}));
EXPECT_TRUE(maxX.isBounded() && *maxX == Fraction(-1, 1));
}
TEST(SimplexTest, addInequality_already_redundant) {
Simplex simplex(1);
addInequality(simplex, {1, -1}); // x >= 1.
addInequality(simplex, {1, 0}); // x >= 0.
simplex.detectRedundant();
ASSERT_FALSE(simplex.isEmpty());
EXPECT_FALSE(simplex.isMarkedRedundant(0));
EXPECT_TRUE(simplex.isMarkedRedundant(1));
}
TEST(SimplexTest, appendVariable) {
Simplex simplex(1);
unsigned snapshot1 = simplex.getSnapshot();
simplex.appendVariable();
simplex.appendVariable(0);
EXPECT_EQ(simplex.getNumVariables(), 2u);
int64_t yMin = 2, yMax = 5;
addInequality(simplex, {0, 1, -yMin}); // y >= 2.
addInequality(simplex, {0, -1, yMax}); // y <= 5.
unsigned snapshot2 = simplex.getSnapshot();
simplex.appendVariable(2);
EXPECT_EQ(simplex.getNumVariables(), 4u);
simplex.rollback(snapshot2);
EXPECT_EQ(simplex.getNumVariables(), 2u);
EXPECT_EQ(simplex.getNumConstraints(), 2u);
EXPECT_EQ(simplex.computeIntegerBounds(getMPIntVec({0, 1, 0})),
std::make_pair(MaybeOptimum<MPInt>(MPInt(yMin)),
MaybeOptimum<MPInt>(MPInt(yMax))));
simplex.rollback(snapshot1);
EXPECT_EQ(simplex.getNumVariables(), 1u);
EXPECT_EQ(simplex.getNumConstraints(), 0u);
}
TEST(SimplexTest, isRedundantInequality) {
Simplex simplex(2);
addInequality(simplex, {0, -1, 2}); // y <= 2.
addInequality(simplex, {1, 0, 0}); // x >= 0.
addEquality(simplex, {-1, 1, 0}); // y = x.
EXPECT_TRUE(isRedundantInequality(simplex, {-1, 0, 2})); // x <= 2.
EXPECT_TRUE(isRedundantInequality(simplex, {0, 1, 0})); // y >= 0.
EXPECT_FALSE(isRedundantInequality(simplex, {-1, 0, -1})); // x <= -1.
EXPECT_FALSE(isRedundantInequality(simplex, {0, 1, -2})); // y >= 2.
EXPECT_FALSE(isRedundantInequality(simplex, {0, 1, -1})); // y >= 1.
}
TEST(SimplexTest, ineqType) {
Simplex simplex(2);
addInequality(simplex, {0, -1, 2}); // y <= 2.
addInequality(simplex, {1, 0, 0}); // x >= 0.
addEquality(simplex, {-1, 1, 0}); // y = x.
EXPECT_EQ(findIneqType(simplex, {-1, 0, 2}),
Simplex::IneqType::Redundant); // x <= 2.
EXPECT_EQ(findIneqType(simplex, {0, 1, 0}),
Simplex::IneqType::Redundant); // y >= 0.
EXPECT_EQ(findIneqType(simplex, {0, 1, -1}),
Simplex::IneqType::Cut); // y >= 1.
EXPECT_EQ(findIneqType(simplex, {-1, 0, 1}),
Simplex::IneqType::Cut); // x <= 1.
EXPECT_EQ(findIneqType(simplex, {0, 1, -2}),
Simplex::IneqType::Cut); // y >= 2.
EXPECT_EQ(findIneqType(simplex, {-1, 0, -1}),
Simplex::IneqType::Separate); // x <= -1.
}
TEST(SimplexTest, isRedundantEquality) {
Simplex simplex(2);
addInequality(simplex, {0, -1, 2}); // y <= 2.
addInequality(simplex, {1, 0, 0}); // x >= 0.
addEquality(simplex, {-1, 1, 0}); // y = x.
EXPECT_TRUE(isRedundantEquality(simplex, {-1, 1, 0})); // y = x.
EXPECT_TRUE(isRedundantEquality(simplex, {1, -1, 0})); // x = y.
EXPECT_FALSE(isRedundantEquality(simplex, {0, 1, -1})); // y = 1.
addEquality(simplex, {0, -1, 2}); // y = 2.
EXPECT_TRUE(isRedundantEquality(simplex, {-1, 0, 2})); // x = 2.
}
TEST(SimplexTest, IsRationalSubsetOf) {
IntegerPolyhedron univ = parseIntegerPolyhedron("(x) : ()");
IntegerPolyhedron empty =
parseIntegerPolyhedron("(x) : (x + 0 >= 0, -x - 1 >= 0)");
IntegerPolyhedron s1 = parseIntegerPolyhedron("(x) : ( x >= 0, -x + 4 >= 0)");
IntegerPolyhedron s2 =
parseIntegerPolyhedron("(x) : (x - 1 >= 0, -x + 3 >= 0)");
Simplex simUniv(univ);
Simplex simEmpty(empty);
Simplex sim1(s1);
Simplex sim2(s2);
EXPECT_TRUE(simUniv.isRationalSubsetOf(univ));
EXPECT_TRUE(simEmpty.isRationalSubsetOf(empty));
EXPECT_TRUE(sim1.isRationalSubsetOf(s1));
EXPECT_TRUE(sim2.isRationalSubsetOf(s2));
EXPECT_TRUE(simEmpty.isRationalSubsetOf(univ));
EXPECT_TRUE(simEmpty.isRationalSubsetOf(s1));
EXPECT_TRUE(simEmpty.isRationalSubsetOf(s2));
EXPECT_TRUE(simEmpty.isRationalSubsetOf(empty));
EXPECT_TRUE(simUniv.isRationalSubsetOf(univ));
EXPECT_FALSE(simUniv.isRationalSubsetOf(s1));
EXPECT_FALSE(simUniv.isRationalSubsetOf(s2));
EXPECT_FALSE(simUniv.isRationalSubsetOf(empty));
EXPECT_TRUE(sim1.isRationalSubsetOf(univ));
EXPECT_TRUE(sim1.isRationalSubsetOf(s1));
EXPECT_FALSE(sim1.isRationalSubsetOf(s2));
EXPECT_FALSE(sim1.isRationalSubsetOf(empty));
EXPECT_TRUE(sim2.isRationalSubsetOf(univ));
EXPECT_TRUE(sim2.isRationalSubsetOf(s1));
EXPECT_TRUE(sim2.isRationalSubsetOf(s2));
EXPECT_FALSE(sim2.isRationalSubsetOf(empty));
}
TEST(SimplexTest, addDivisionVariable) {
Simplex simplex(/*nVar=*/1);
simplex.addDivisionVariable(getMPIntVec({1, 0}), MPInt(2));
addInequality(simplex, {1, 0, -3}); // x >= 3.
addInequality(simplex, {-1, 0, 9}); // x <= 9.
Optional<SmallVector<MPInt, 8>> sample = simplex.findIntegerSample();
ASSERT_TRUE(sample.has_value());
EXPECT_EQ((*sample)[0] / 2, (*sample)[1]);
}
TEST(SimplexTest, LexIneqType) {
LexSimplex simplex(/*nVar=*/1);
addInequality(simplex, {2, -1}); // x >= 1/2.
// Redundant inequality x >= 2/3.
EXPECT_TRUE(isRedundantInequality(simplex, {3, -2}));
EXPECT_FALSE(isSeparateInequality(simplex, {3, -2}));
// Separate inequality x <= 2/3.
EXPECT_FALSE(isRedundantInequality(simplex, {-3, 2}));
EXPECT_TRUE(isSeparateInequality(simplex, {-3, 2}));
// Cut inequality x <= 1.
EXPECT_FALSE(isRedundantInequality(simplex, {-1, 1}));
EXPECT_FALSE(isSeparateInequality(simplex, {-1, 1}));
}