"""For more tests on satisfiability, see test_dimacs""" from sympy.assumptions.ask import Q from sympy.core.symbol import symbols from sympy.logic.boolalg import And, Implies, Equivalent, true, false from sympy.logic.inference import literal_symbol, \ pl_true, satisfiable, valid, entails, PropKB from sympy.logic.algorithms.dpll import dpll, dpll_satisfiable, \ find_pure_symbol, find_unit_clause, unit_propagate, \ find_pure_symbol_int_repr, find_unit_clause_int_repr, \ unit_propagate_int_repr from sympy.logic.algorithms.dpll2 import dpll_satisfiable as dpll2_satisfiable from sympy.testing.pytest import raises def test_literal(): A, B = symbols('A,B') assert literal_symbol(True) is True assert literal_symbol(False) is False assert literal_symbol(A) is A assert literal_symbol(~A) is A def test_find_pure_symbol(): A, B, C = symbols('A,B,C') assert find_pure_symbol([A], [A]) == (A, True) assert find_pure_symbol([A, B], [~A | B, ~B | A]) == (None, None) assert find_pure_symbol([A, B, C], [ A | ~B, ~B | ~C, C | A]) == (A, True) assert find_pure_symbol([A, B, C], [~A | B, B | ~C, C | A]) == (B, True) assert find_pure_symbol([A, B, C], [~A | ~B, ~B | ~C, C | A]) == (B, False) assert find_pure_symbol( [A, B, C], [~A | B, ~B | ~C, C | A]) == (None, None) def test_find_pure_symbol_int_repr(): assert find_pure_symbol_int_repr([1], [{1}]) == (1, True) assert find_pure_symbol_int_repr([1, 2], [{-1, 2}, {-2, 1}]) == (None, None) assert find_pure_symbol_int_repr([1, 2, 3], [{1, -2}, {-2, -3}, {3, 1}]) == (1, True) assert find_pure_symbol_int_repr([1, 2, 3], [{-1, 2}, {2, -3}, {3, 1}]) == (2, True) assert find_pure_symbol_int_repr([1, 2, 3], [{-1, -2}, {-2, -3}, {3, 1}]) == (2, False) assert find_pure_symbol_int_repr([1, 2, 3], [{-1, 2}, {-2, -3}, {3, 1}]) == (None, None) def test_unit_clause(): A, B, C = symbols('A,B,C') assert find_unit_clause([A], {}) == (A, True) assert find_unit_clause([A, ~A], {}) == (A, True) # Wrong ?? assert find_unit_clause([A | B], {A: True}) == (B, True) assert find_unit_clause([A | B], {B: True}) == (A, True) assert find_unit_clause( [A | B | C, B | ~C, A | ~B], {A: True}) == (B, False) assert find_unit_clause([A | B | C, B | ~C, A | B], {A: True}) == (B, True) assert find_unit_clause([A | B | C, B | ~C, A ], {}) == (A, True) def test_unit_clause_int_repr(): assert find_unit_clause_int_repr(map(set, [[1]]), {}) == (1, True) assert find_unit_clause_int_repr(map(set, [[1], [-1]]), {}) == (1, True) assert find_unit_clause_int_repr([{1, 2}], {1: True}) == (2, True) assert find_unit_clause_int_repr([{1, 2}], {2: True}) == (1, True) assert find_unit_clause_int_repr(map(set, [[1, 2, 3], [2, -3], [1, -2]]), {1: True}) == (2, False) assert find_unit_clause_int_repr(map(set, [[1, 2, 3], [3, -3], [1, 2]]), {1: True}) == (2, True) A, B, C = symbols('A,B,C') assert find_unit_clause([A | B | C, B | ~C, A ], {}) == (A, True) def test_unit_propagate(): A, B, C = symbols('A,B,C') assert unit_propagate([A | B], A) == [] assert unit_propagate([A | B, ~A | C, ~C | B, A], A) == [C, ~C | B, A] def test_unit_propagate_int_repr(): assert unit_propagate_int_repr([{1, 2}], 1) == [] assert unit_propagate_int_repr(map(set, [[1, 2], [-1, 3], [-3, 2], [1]]), 1) == [{3}, {-3, 2}] def test_dpll(): """This is also tested in test_dimacs""" A, B, C = symbols('A,B,C') assert dpll([A | B], [A, B], {A: True, B: True}) == {A: True, B: True} def test_dpll_satisfiable(): A, B, C = symbols('A,B,C') assert dpll_satisfiable( A & ~A ) is False assert dpll_satisfiable( A & ~B ) == {A: True, B: False} assert dpll_satisfiable( A | B ) in ({A: True}, {B: True}, {A: True, B: True}) assert dpll_satisfiable( (~A | B) & (~B | A) ) in ({A: True, B: True}, {A: False, B: False}) assert dpll_satisfiable( (A | B) & (~B | C) ) in ({A: True, B: False}, {A: True, C: True}, {B: True, C: True}) assert dpll_satisfiable( A & B & C ) == {A: True, B: True, C: True} assert dpll_satisfiable( (A | B) & (A >> B) ) == {B: True} assert dpll_satisfiable( Equivalent(A, B) & A ) == {A: True, B: True} assert dpll_satisfiable( Equivalent(A, B) & ~A ) == {A: False, B: False} def test_dpll2_satisfiable(): A, B, C = symbols('A,B,C') assert dpll2_satisfiable( A & ~A ) is False assert dpll2_satisfiable( A & ~B ) == {A: True, B: False} assert dpll2_satisfiable( A | B ) in ({A: True}, {B: True}, {A: True, B: True}) assert dpll2_satisfiable( (~A | B) & (~B | A) ) in ({A: True, B: True}, {A: False, B: False}) assert dpll2_satisfiable( (A | B) & (~B | C) ) in ({A: True, B: False, C: True}, {A: True, B: True, C: True}) assert dpll2_satisfiable( A & B & C ) == {A: True, B: True, C: True} assert dpll2_satisfiable( (A | B) & (A >> B) ) in ({B: True, A: False}, {B: True, A: True}) assert dpll2_satisfiable( Equivalent(A, B) & A ) == {A: True, B: True} assert dpll2_satisfiable( Equivalent(A, B) & ~A ) == {A: False, B: False} def test_minisat22_satisfiable(): A, B, C = symbols('A,B,C') minisat22_satisfiable = lambda expr: satisfiable(expr, algorithm="minisat22") assert minisat22_satisfiable( A & ~A ) is False assert minisat22_satisfiable( A & ~B ) == {A: True, B: False} assert minisat22_satisfiable( A | B ) in ({A: True}, {B: False}, {A: False, B: True}, {A: True, B: True}, {A: True, B: False}) assert minisat22_satisfiable( (~A | B) & (~B | A) ) in ({A: True, B: True}, {A: False, B: False}) assert minisat22_satisfiable( (A | B) & (~B | C) ) in ({A: True, B: False, C: True}, {A: True, B: True, C: True}, {A: False, B: True, C: True}, {A: True, B: False, C: False}) assert minisat22_satisfiable( A & B & C ) == {A: True, B: True, C: True} assert minisat22_satisfiable( (A | B) & (A >> B) ) in ({B: True, A: False}, {B: True, A: True}) assert minisat22_satisfiable( Equivalent(A, B) & A ) == {A: True, B: True} assert minisat22_satisfiable( Equivalent(A, B) & ~A ) == {A: False, B: False} def test_minisat22_minimal_satisfiable(): A, B, C = symbols('A,B,C') minisat22_satisfiable = lambda expr, minimal=True: satisfiable(expr, algorithm="minisat22", minimal=True) assert minisat22_satisfiable( A & ~A ) is False assert minisat22_satisfiable( A & ~B ) == {A: True, B: False} assert minisat22_satisfiable( A | B ) in ({A: True}, {B: False}, {A: False, B: True}, {A: True, B: True}, {A: True, B: False}) assert minisat22_satisfiable( (~A | B) & (~B | A) ) in ({A: True, B: True}, {A: False, B: False}) assert minisat22_satisfiable( (A | B) & (~B | C) ) in ({A: True, B: False, C: True}, {A: True, B: True, C: True}, {A: False, B: True, C: True}, {A: True, B: False, C: False}) assert minisat22_satisfiable( A & B & C ) == {A: True, B: True, C: True} assert minisat22_satisfiable( (A | B) & (A >> B) ) in ({B: True, A: False}, {B: True, A: True}) assert minisat22_satisfiable( Equivalent(A, B) & A ) == {A: True, B: True} assert minisat22_satisfiable( Equivalent(A, B) & ~A ) == {A: False, B: False} g = satisfiable((A | B | C),algorithm="minisat22",minimal=True,all_models=True) sol = next(g) first_solution = {key for key, value in sol.items() if value} sol=next(g) second_solution = {key for key, value in sol.items() if value} sol=next(g) third_solution = {key for key, value in sol.items() if value} assert not first_solution <= second_solution assert not second_solution <= third_solution assert not first_solution <= third_solution def test_satisfiable(): A, B, C = symbols('A,B,C') assert satisfiable(A & (A >> B) & ~B) is False def test_valid(): A, B, C = symbols('A,B,C') assert valid(A >> (B >> A)) is True assert valid((A >> (B >> C)) >> ((A >> B) >> (A >> C))) is True assert valid((~B >> ~A) >> (A >> B)) is True assert valid(A | B | C) is False assert valid(A >> B) is False def test_pl_true(): A, B, C = symbols('A,B,C') assert pl_true(True) is True assert pl_true( A & B, {A: True, B: True}) is True assert pl_true( A | B, {A: True}) is True assert pl_true( A | B, {B: True}) is True assert pl_true( A | B, {A: None, B: True}) is True assert pl_true( A >> B, {A: False}) is True assert pl_true( A | B | ~C, {A: False, B: True, C: True}) is True assert pl_true(Equivalent(A, B), {A: False, B: False}) is True # test for false assert pl_true(False) is False assert pl_true( A & B, {A: False, B: False}) is False assert pl_true( A & B, {A: False}) is False assert pl_true( A & B, {B: False}) is False assert pl_true( A | B, {A: False, B: False}) is False #test for None assert pl_true(B, {B: None}) is None assert pl_true( A & B, {A: True, B: None}) is None assert pl_true( A >> B, {A: True, B: None}) is None assert pl_true(Equivalent(A, B), {A: None}) is None assert pl_true(Equivalent(A, B), {A: True, B: None}) is None # Test for deep assert pl_true(A | B, {A: False}, deep=True) is None assert pl_true(~A & ~B, {A: False}, deep=True) is None assert pl_true(A | B, {A: False, B: False}, deep=True) is False assert pl_true(A & B & (~A | ~B), {A: True}, deep=True) is False assert pl_true((C >> A) >> (B >> A), {C: True}, deep=True) is True def test_pl_true_wrong_input(): from sympy.core.numbers import pi raises(ValueError, lambda: pl_true('John Cleese')) raises(ValueError, lambda: pl_true(42 + pi + pi ** 2)) raises(ValueError, lambda: pl_true(42)) def test_entails(): A, B, C = symbols('A, B, C') assert entails(A, [A >> B, ~B]) is False assert entails(B, [Equivalent(A, B), A]) is True assert entails((A >> B) >> (~A >> ~B)) is False assert entails((A >> B) >> (~B >> ~A)) is True def test_PropKB(): A, B, C = symbols('A,B,C') kb = PropKB() assert kb.ask(A >> B) is False assert kb.ask(A >> (B >> A)) is True kb.tell(A >> B) kb.tell(B >> C) assert kb.ask(A) is False assert kb.ask(B) is False assert kb.ask(C) is False assert kb.ask(~A) is False assert kb.ask(~B) is False assert kb.ask(~C) is False assert kb.ask(A >> C) is True kb.tell(A) assert kb.ask(A) is True assert kb.ask(B) is True assert kb.ask(C) is True assert kb.ask(~C) is False kb.retract(A) assert kb.ask(C) is False def test_propKB_tolerant(): """"tolerant to bad input""" kb = PropKB() A, B, C = symbols('A,B,C') assert kb.ask(B) is False def test_satisfiable_non_symbols(): x, y = symbols('x y') assumptions = Q.zero(x*y) facts = Implies(Q.zero(x*y), Q.zero(x) | Q.zero(y)) query = ~Q.zero(x) & ~Q.zero(y) refutations = [ {Q.zero(x): True, Q.zero(x*y): True}, {Q.zero(y): True, Q.zero(x*y): True}, {Q.zero(x): True, Q.zero(y): True, Q.zero(x*y): True}, {Q.zero(x): True, Q.zero(y): False, Q.zero(x*y): True}, {Q.zero(x): False, Q.zero(y): True, Q.zero(x*y): True}] assert not satisfiable(And(assumptions, facts, query), algorithm='dpll') assert satisfiable(And(assumptions, facts, ~query), algorithm='dpll') in refutations assert not satisfiable(And(assumptions, facts, query), algorithm='dpll2') assert satisfiable(And(assumptions, facts, ~query), algorithm='dpll2') in refutations def test_satisfiable_bool(): from sympy.core.singleton import S assert satisfiable(true) == {true: true} assert satisfiable(S.true) == {true: true} assert satisfiable(false) is False assert satisfiable(S.false) is False def test_satisfiable_all_models(): from sympy.abc import A, B assert next(satisfiable(False, all_models=True)) is False assert list(satisfiable((A >> ~A) & A, all_models=True)) == [False] assert list(satisfiable(True, all_models=True)) == [{true: true}] models = [{A: True, B: False}, {A: False, B: True}] result = satisfiable(A ^ B, all_models=True) models.remove(next(result)) models.remove(next(result)) raises(StopIteration, lambda: next(result)) assert not models assert list(satisfiable(Equivalent(A, B), all_models=True)) == \ [{A: False, B: False}, {A: True, B: True}] models = [{A: False, B: False}, {A: False, B: True}, {A: True, B: True}] for model in satisfiable(A >> B, all_models=True): models.remove(model) assert not models # This is a santiy test to check that only the required number # of solutions are generated. The expr below has 2**100 - 1 models # which would time out the test if all are generated at once. from sympy.utilities.iterables import numbered_symbols from sympy.logic.boolalg import Or sym = numbered_symbols() X = [next(sym) for i in range(100)] result = satisfiable(Or(*X), all_models=True) for i in range(10): assert next(result)