def test_exact_cover(self):
""" Exact Cover test """
algo = NumPyMinimumEigensolver()
result = algo.compute_minimum_eigenvalue(operator=self.qubit_op, aux_operators=[])
x = sample_most_likely(result.eigenstate)
ising_sol = exact_cover.get_solution(x)
np.testing.assert_array_equal(ising_sol, [0, 1, 1, 0])
oracle = self._brute_force()
self.assertEqual(exact_cover.check_solution_satisfiability(ising_sol, self.list_of_subsets),
oracle)
def test_exact_cover_vqe(self):
""" Exact Cover VQE test """
algorithm_globals.random_seed = 10598
q_i = QuantumInstance(BasicAer.get_backend('statevector_simulator'),
seed_simulator=algorithm_globals.random_seed,
seed_transpiler=algorithm_globals.random_seed)
result = VQE(EfficientSU2(self.qubit_op.num_qubits, reps=5),
COBYLA(),
max_evals_grouped=2,
quantum_instance=q_i).compute_minimum_eigenvalue(operator=self.qubit_op)
x = sample_most_likely(result.eigenstate)
ising_sol = exact_cover.get_solution(x)
oracle = self._brute_force()
self.assertEqual(exact_cover.check_solution_satisfiability(ising_sol, self.list_of_subsets),
oracle)
def _brute_force(self):
# brute-force way: try every possible assignment!
has_sol = False
def bitfield(n, length):
result = np.binary_repr(n, length)
return [int(digit) for digit in result] # [2:] to chop off the "0b" part
subsets = len(self.list_of_subsets)
maximum = 2 ** subsets
for i in range(maximum):
cur = bitfield(i, subsets)
cur_v = exact_cover.check_solution_satisfiability(cur, self.list_of_subsets)
if cur_v:
has_sol = True
break
return has_sol