def comparing_two_variable_orders():
n = 6
# declare variables
vrs = ['x{i}'.format(i=i) for i in range(2 * n)]
bdd = _bdd.BDD()
bdd.declare(*vrs)
# equality constraints cause difficulties with BDD size
expr_1 = r' /\ '.join(
" x{i} <=> x{j} ".format(i=i, j=(i + n + 1) % (2*n)) for i in range(n))
u = bdd.add_expr(expr_1)
expr_2 = r' /\ '.join(
" x{i} <=> x{j} ".format(i=2 * i, j=(2 * i + 1)) for i in range(n))
v = bdd.add_expr(expr_2)
bdd.collect_garbage()
# an order that yields a small BDD for `expr`
good_order = ['x{i}'.format(i=i - 1) for i in
[1, 7, 3, 9, 5, 11,
2, 8, 4, 10, 6, 12]]
# an order that yields a large BDD for `expr`
bad_order = list(vrs)
# plot
_bdd.reorder(bdd, list_to_dict(good_order))
bdd.dump('good.pdf')
_bdd.reorder(bdd, list_to_dict(bad_order))
bdd.dump('bad.pdf')
def comparing_two_variable_orders():
n = 6
# declare variables
vrs = ['x{i}'.format(i=i) for i in range(2 * n)]
bdd = _bdd.BDD()
bdd.declare(*vrs)
# equality constraints cause difficulties with BDD size
expr_1 = r' /\ '.join(
" x{i} <=> x{j} ".format(i=i, j=(i + n + 1) % (2*n)) for i in range(n))
u = bdd.add_expr(expr_1)
expr_2 = r' /\ '.join(
" x{i} <=> x{j} ".format(i=2 * i, j=(2 * i + 1)) for i in range(n))
v = bdd.add_expr(expr_2)
bdd.collect_garbage()
# an order that yields a small BDD for `expr`
good_order = ['x{i}'.format(i=i - 1) for i in
[1, 7, 3, 9, 5, 11,
2, 8, 4, 10, 6, 12]]
# an order that yields a large BDD for `expr`
bad_order = list(vrs)
# plot
_bdd.reorder(bdd, list_to_dict(good_order))
bdd.dump('good.pdf')
_bdd.reorder(bdd, list_to_dict(bad_order))
bdd.dump('bad.pdf')
def dump_bdd_using_autoref(u, fname):
# copy from `dd.cudd` to `dd.autoref`
b = autoref.BDD()
cudd_bdd = u.bdd
_bdd.copy_vars(cudd_bdd, b)
r = _bdd.copy_bdd(u, cudd_bdd, b)
autoref.reorder(b)
b.dump(fname, [r])
print('dumped BDD to file "{f}"'.format(f=fname))
def demo_static_reordering():
"""How to invoke reordering explicitly."""
print(
'\n' + (50 * '-') +
'\ndemo of static reordering\n' +
(50 * '-'))
bdd = _bdd.BDD()
bdd.declare('z1', 'z2', 'z3', 'y1', 'y2', 'y3')
expr = '(z1 /\ y1) \/ (z2 /\ y2) \/ (z3 /\ y3)'
u = bdd.add_expr(expr)
print_manager_size(bdd)
# invoke sifting
_bdd.reorder(bdd)
print_manager_size(bdd)
def demo_specific_var_order():
"""How to permute the variables to a desired order."""
print(
'\n' + (50 * '-') +
'\ndemo of user-defined variable permutation\n' +
(50 * '-'))
bdd = _bdd.BDD()
bdd.declare('a', 'b', 'c')
u = bdd.add_expr('(a \/ b) /\ ~ c')
print_var_levels(bdd)
# reorder
desired_order = dict(a=2, b=0, c=1)
_bdd.reorder(bdd, desired_order)
# confirm
print_var_levels(bdd)
def bdd_img_special_order(exp, order):
bdd = _bdd.BDD()
bdd.configure(reordering = True)
order_dict = dict((k.strip(), int(v.strip())) for k,v in
(item.split(':') for item in order.split(',')))
for key, value in order_dict.items():
bdd.add_var(key)
u = bdd.add_expr(exp)
# print(order_dict)
# print(bdd.vars)
_bdd.reorder(bdd, order_dict)
# print(bdd.vars)
bdd.collect_garbage()
rand = str(randrange(0, 100))
bdd.dump('../images/bdd_reorder_special' + rand + '.png')
global filename_reorder_special
filename_reorder_special = '../images/bdd_reorder_special' + rand + '.png'
def test_reorder_2():
bdd = _bdd.BDD()
vrs = [
'x', 'y', 'z', 'a', 'b', 'c', 'e', 'z1', 'z2', 'z3', 'y1', 'y2', 'y3'
]
bdd = _bdd.BDD()
bdd.declare(*vrs)
expr_1 = '(~ z \/ (c /\ b)) /\ e /\ (a /\ (~ x \/ y))'
# Figs. 6.24, 6.25 Baier 2008
expr_2 = '(z1 /\ y1) \/ (z2 /\ y2) \/ (z3 /\ y3)'
u = bdd.add_expr(expr_1)
v = bdd.add_expr(expr_2)
bdd.collect_garbage()
n = len(bdd)
assert n == 23, n
_bdd.reorder(bdd)
n_ = len(bdd)
assert n > n_, (n, n_)
bdd.assert_consistent()
def test_function_properties():
bdd = _bdd.BDD()
bdd.declare('x', 'y')
order = dict(x=0, y=1)
_bdd.reorder(bdd, order)
u = bdd.add_expr('x \/ y')
y = bdd.add_expr('y')
# Assigned first because in presence of a bug
# different property calls could yield
# different values.
level = u.level
assert level == 0, level
var = u.var
assert var == 'x', var
low = u.low
assert low == y, low
high = u.high
assert high == bdd.true, high
ref = u.ref
assert ref == 1, ref
assert not u.negated
support = u.support
assert support == {'x', 'y'}, support
def comparing_two_variable_orders():
n = 6
# declare variables
vrs = ['x{i}'.format(i=i) for i in range(n)]
primed_vars = [prime(var) for var in vrs]
bdd = _bdd.BDD()
bdd.declare(*(vrs + primed_vars))
# equality constraints cause difficulties with BDD size
expr = r' /\ '.join(
" {var} <=> {var}' ".format(var=var) for var in vrs)
u = bdd.add_expr(expr)
bdd.collect_garbage()
# an order that yields a small BDD for `expr`
good_order = list()
for var in vrs:
good_order.extend([var, prime(var)])
# an order that yields a large BDD for `expr`
bad_order = list(vrs)
bad_order.extend(prime(var) for var in vrs)
# plot
_bdd.reorder(bdd, list_to_dict(good_order))
bdd.dump('good.pdf')
_bdd.reorder(bdd, list_to_dict(bad_order))
bdd.dump('bad.pdf')
def test_reorder():
bdd = _bdd.BDD()
bdd.declare('x', 'y', 'z')
u = bdd.add_expr('(x /\ y) \/ z')
_bdd.reorder(bdd)
assert u in bdd
