def _add_base_clause(self: Formula, clause: List[int]) -> None:
"""Add a clause to the formula, only during initialization.
"""
clause_object = Clause(clause)
self.formula.append(clause_object)
head_var, tail_var = clause_object.get_head_tail_var()
if head_var not in self.variable_clauses:
self.variable_clauses[head_var] = set()
self.variable_clauses[head_var].add(clause_object)
if tail_var not in self.variable_clauses:
self.variable_clauses[tail_var] = set()
self.variable_clauses[tail_var].add(clause_object)
if len(clause) == 1:
self.unit_clauses.add(clause_object)
def add_clause(self: Formula, clause: List[int]) -> None:
"""Add a clause to the formula after initialization.
:param clause: a list of `Literal`s that are contained in the clause;
each variable must appear in `clause` at most once. `clause` cannot contain literals
in variables not already present in the representation.
"""
clause_object = Clause(clause)
clause_object.assign(self.assignment)
self.formula.append(clause_object)
# update mutation history and state history
old_head_var, old_tail_var = clause_object.get_head_tail_var()
was_valid = False
was_unsat = len(clause) == 0
for d in range(0, self.decision_level + 1):
clause_object.assign_decision_level(self.assignment, d)
state, head_var, tail_var = clause_object.get_state(
self.assignment.get_assignment_at_level(d))
if head_var != old_head_var or tail_var != old_tail_var:
self.mutation_history[d].add(clause_object)
# can actually be commented out since we never make
# decisions while the formila is valid or unsat
was_valid = was_valid or state == Clause.SATISFIED
was_unsat = was_unsat or state == Clause.UNSATISFIED
if self.state_history[d] == Formula.SATISFIED and not was_valid:
self.state_history[d] = Formula.UNRESOLVED
if was_unsat:
self.state_history[d] = Formula.UNSATISFIED
# update current state
state, head_var, tail_var = clause_object.get_state(self.assignment)
if state == Clause.UNRESOLVED or state == Clause.UNIT:
if head_var not in self.variable_clauses:
self.variable_clauses[head_var] = set()
self.variable_clauses[head_var].add(clause_object)
if tail_var not in self.variable_clauses:
self.variable_clauses[tail_var] = set()
self.variable_clauses[tail_var].add(clause_object)
# update unit clauses
if state == Clause.UNIT:
self.unit_clauses.add(clause_object)
# update unsat clauses
if state == Clause.UNSATISFIED:
self.unsat_clauses.add(clause_object)
def test_init(self: TestClause):
clause = Clause([-6, 5, -4, 3, -2, 1])
self.assertEqual(clause.get_head_tail_var(), (6, 1))