def zero_blocks(self, f):
"""divides the zero set of f into blocks
>>> from polybori import *
>>> r = declare_ring(["x", "y", "z"], dict())
>>> e = CNFEncoder(r)
>>> e.zero_blocks(r.variable(0)*r.variable(1)*r.variable(2))
[{y: 0}, {z: 0}, {x: 0}]
"""
f = Polynomial(f)
variables = f.vars_as_monomial()
space = variables.divisors()
variables = list(variables.variables())
zeros = f.zeros_in(space)
rest = zeros
res = list()
def choose_old(s):
return iter(rest).next() # somewhat
#inefficient compared to polynomials lex_lead
def choose(s):
indices = []
assert not s.empty()
nav = s.navigation()
while not nav.constant():
e = nav.else_branch()
t = nav.then_branch()
if e.constant() and not e.terminal_one():
indices.append(nav.value())
nav = t
else:
if self.random_generator.randint(0, 1):
indices.append(nav.value())
nav = t
else:
nav = e
assert nav.terminal_one()
res = self.one_set
for i in reversed(indices):
res = ite(i, res, self.empty_set)
return iter(res).next()
while not rest.empty():
l = choose(rest)
l_variables = set(l.variables())
def get_val(var):
if var in l_variables:
return 1
return 0
block_dict = dict([(v, get_val(v)) for v in variables])
l = l.set()
self.random_generator.shuffle(variables)
for v in variables:
candidate = l.change(v.index())
if candidate.diff(zeros).empty():
l = l.union(candidate)
del block_dict[v]
rest = rest.diff(l)
res.append(block_dict)
return res
def zero_blocks(self, f):
"""divides the zero set of f into blocks
>>> from polybori import *
>>> r = declare_ring(["x", "y", "z"], dict())
>>> e = CNFEncoder(r)
>>> e.zero_blocks(r.variable(0)*r.variable(1)*r.variable(2))
[{y: 0}, {z: 0}, {x: 0}]
"""
f=Polynomial(f)
variables = f.vars_as_monomial()
space = variables.divisors()
variables = list(variables.variables())
zeros = f.zeros_in(space)
rest = zeros
res = list()
def choose_old(s):
return iter(rest).next()# somewhat
#inefficient compared to polynomials lex_lead
def choose(s):
indices = []
assert not s.empty()
nav = s.navigation()
while not nav.constant():
e = nav.else_branch()
t = nav.then_branch()
if e.constant() and not e.terminal_one():
indices.append(nav.value())
nav = t
else:
if self.random_generator.randint(0,1):
indices.append(nav.value())
nav = t
else:
nav = e
assert nav.terminal_one()
res = self.one_set
for i in reversed(indices):
res = ite(i, res, self.empty_set)
return iter(res).next()
while not rest.empty():
l = choose(rest)
l_variables = set(l.variables())
def get_val(var):
if var in l_variables:
return 1
return 0
block_dict = dict([(v, get_val(v)) for v in variables])
l = l.set()
self.random_generator.shuffle(variables)
for v in variables:
candidate = l.change(v.index())
if candidate.diff(zeros).empty():
l = l.union(candidate)
del block_dict[v]
rest = rest.diff(l)
res.append(block_dict)
return res
