def iff_clause(self, tseitin_literal_x, tseitin_literal_y):
"""
get equation (x <-> y) and append to f (x <-> y) <-> g
witch in CNF it: (x||-y||-g)&&(-x||y||-g)&&(g||y||x)&&(-x||-y||g)
:param tseitin_literal_x
:param tseitin_literal_y
:return: the new name of (x <-> y)
"""
g = Literal(self.generate_name())
c = Clause()
c.append(tseitin_literal_x)
c.append(-tseitin_literal_y)
c.append(-g)
self.f.append(c)
c = Clause()
c.append(-tseitin_literal_x)
c.append(tseitin_literal_y)
c.append(-g)
self.f.append(c)
c = Clause()
c.append(-tseitin_literal_x)
c.append(-tseitin_literal_y)
c.append(g)
self.f.append(c)
c = Clause()
c.append(tseitin_literal_x)
c.append(tseitin_literal_y)
c.append(g)
self.f.append(c)
return g
def not_clause(self, tseitin_literal):
g = Literal(self.generate_name())
c = Clause()
c.append(-tseitin_literal)
c.append(-g)
self.f.append(c)
c = Clause()
c.append(tseitin_literal)
c.append(g)
self.f.append(c)
return g
def resolve_conflict(self):
calc_conflict = Clause()
for l in self.imp_graph.lit_assign_ord:
calc_conflict.append(-l)
f_len = len(self.formula)
f_doc = self.formula
conf_doc = self.conflict
if self.lvl == 0:
self.set_unsat()
return
learnt_clause = self.imp_graph.explain(self.conflict,
self.last_decision[0])
self.imp_graph.del_conflicts()
lvls = set([self.var_assign[l.x]["lvl"] for l in learnt_clause])
if len(lvls) == 1:
if lvls.pop() == 0:
self.set_unsat()
return
else:
backjump_lvl = 0
else:
lvls.remove(max(lvls))
backjump_lvl = max(lvls)
self.backjump(backjump_lvl)
self.add_clause(learnt_clause)
self.conflict = None
if (f_len + 1) != len(self.formula):
raise Exception("No clause learnt: " + str(learnt_clause) +
"\n Old formula=" + str(f_doc) + "\nNew formula=" +
str(self.formula) + "\nOriginal conflict=" +
str(conf_doc) + "\nExplained=" +
str(learnt_clause) + "\nCalculated=" +
str(calc_conflict))
def resolve_clauses(c1, c2, lit):
if (lit in c1) and (-lit in c2):
pos = c1
neg = c2
elif (lit in c2) and (-lit in c1):
pos = c2
neg = c1
else:
raise Exception(
"Attempt to resolve clauses around a wrong literal. c1={} and c2={} literal={}"
.format(c1, c2, lit))
new_clause = Clause()
for l in pos:
if l != lit:
new_clause.append(l)
for l in neg:
if l != -lit:
new_clause.append(l)
return new_clause
def run_TsetinTransformation(self, tree):
self.parser(tree)
c = Clause()
c.append(self.var_name)
self.f.append(c)
return self.f
from SAT.Preprocess import remove_redundant_clauses
from SAT.CNF_formula import CNF_formula, Clause, Literal
from SAT.Assignment import Assignment
f = CNF_formula()
c1 = Clause()
c2 = Clause()
c3 = Clause()
c4 = Clause()
for i in {1, -4}:
c1.append(Literal(i))
for i in {2}:
c2.append(Literal(i))
for i in {-2, 3}:
c3.append(Literal(i))
for i in {-2, -3, 4}:
c4.append(Literal(i))
f.append(c1)
f.append(c2)
f.append(c3)
f.append(c4)
print("Original formula={}\n".format(f))
a = Assignment(f)
print("Initial Assignment:{}".format(a))
a.plp_iteration()
print("Assignment after PLP:{}".format(a))
from SAT.Preprocess import remove_redundant_clauses
from SAT.CNF_formula import CNF_formula, Clause, Literal
f = CNF_formula()
c1 = Clause()
c2 = Clause()
c3 = Clause()
c4 = Clause()
c5 = Clause()
c6 = Clause()
for i in {1, 2, 3}:
c1.append(Literal(i))
c2.append(Literal(i))
for i in {1, 2, 2}:
c3.append(Literal(i))
for i in {1, 2, -2}:
c4.append(Literal(i))
f.append(c1)
f.append(c2)
f.append(c3)
f.append(c4)
f.append(c5)
f.append(c6)
f_pp = remove_redundant_clauses(f)
f_target = CNF_formula()
c1_target = Clause()
c2_target = Clause()