def get_bounds(self, formula_manager=None):
fm = smt if formula_manager is None else formula_manager
bounds = []
for v, (lb, ub) in self.var_domains.items():
symbol = self.get_symbol(v, formula_manager)
if lb is not None:
bounds.append(smt.LE(smt.Real(float(lb)), symbol))
if ub is not None:
bounds.append(smt.LE(symbol, smt.Real(float(ub))))
return fm.And(*bounds)
def ast_to_smt(self, node):
"""
:type node: Node
"""
def convert_children(number=None):
if number is not None and len(node.children) != number:
raise Exception(
"The number of children ({}) differed from {}".format(
len(node.children), number))
return [self.ast_to_smt(child) for child in node.children]
if node.name == "ite":
return smt.Ite(*convert_children(3))
elif node.name == "~":
return smt.Not(*convert_children(1))
elif node.name == "^":
return smt.Pow(*convert_children(2))
elif node.name == "&":
return smt.And(*convert_children())
elif node.name == "|":
return smt.Or(*convert_children())
elif node.name == "*":
return smt.Times(*convert_children())
elif node.name == "+":
return smt.Plus(*convert_children())
elif node.name == "-":
return smt.Minus(*convert_children(2))
elif node.name == "<=":
return smt.LE(*convert_children(2))
elif node.name == ">=":
return smt.GE(*convert_children(2))
elif node.name == "<":
return smt.LT(*convert_children(2))
elif node.name == ">":
return smt.GT(*convert_children(2))
elif node.name == "=":
return smt.Equals(*convert_children(2))
elif node.name == "const":
c_type, c_value = [child.name for child in node.children]
if c_type == "bool":
return smt.Bool(bool(c_value))
elif c_type == "real":
return smt.Real(float(c_value))
else:
raise Exception("Unknown constant type {}".format(c_type))
elif node.name == "var":
v_type, v_name = [child.name for child in node.children]
if v_type == "bool":
v_smt_type = smt.BOOL
elif v_type == "real":
v_smt_type = smt.REAL
else:
raise Exception("Unknown variable type {}".format(v_type))
return smt.Symbol(v_name, v_smt_type)
else:
raise RuntimeError("Unrecognized node type '{}'".format(node.name))
def _test_to_smt(self, operator):
operator = operator.to_canonical()
# FIXME Integer rounding only applicable if x >= 0
def to_symbol(s):
return smt.Symbol(s, typename=smt.types.INT)
import math
items = [smt.Times(smt.Int(int(math.floor(v))), to_symbol(k)) for k, v in operator.lhs.items()]
lhs = smt.Plus([smt.Int(0)] + items)
rhs = smt.Int(int(math.floor(operator.rhs)))
assert operator.symbol == "<="
return smt.LE(lhs, rhs)
def generate_half_space(domain, real_count):
coefficients = [smt.Real(random.random() * 2 - 1) * domain.get_symbol(domain.real_vars[i]) for i in
range(real_count)]
return smt.LE(smt.Plus(*coefficients), smt.Real(random.random() * 2 - 1))
def __getExpressionTree(symbolicExpression):
# TODO LATER: take into account bitwise shift operations
args = []
castType = None
if len(symbolicExpression.args) > 0:
for symbolicArg in symbolicExpression.args:
arg, type = Solver.__getExpressionTree(symbolicArg)
args.append(arg)
if castType is None:
castType = type
else:
if castType.literal == 'Integer':
if type.literal == 'Real':
castType = type
# TODO LATER: consider other possible castings
if castType.literal == 'Real':
for i in range(len(args)):
args[i] = pysmt.ToReal(args[i])
if isinstance(symbolicExpression, sympy.Not):
if castType.literal == 'Integer':
return pysmt.Equals(args[0], pysmt.Int(0)), Type('Bool')
elif castType.literal == 'Real':
return pysmt.Equals(args[0], pysmt.Real(0)), Type('Bool')
elif castType.literal == 'Bool':
return pysmt.Not(args[0]), Type('Bool')
else: # castType.literal == 'BitVector'
return pysmt.BVNot(args[0]), Type('BitVector')
elif isinstance(symbolicExpression, sympy.Lt):
return pysmt.LT(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.Gt):
return pysmt.GT(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.Ge):
return pysmt.GE(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.Le):
return pysmt.LE(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.Eq):
return pysmt.Equals(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.Ne):
return pysmt.NotEquals(args[0], args[1]), Type('Bool')
elif isinstance(symbolicExpression, sympy.And):
if castType.literal == 'Bool':
return pysmt.And(args[0], args[1]), Type('Bool')
else: # type.literal == 'BitVector'
return pysmt.BVAnd(args[0], args[1]), castType
elif isinstance(symbolicExpression, sympy.Or):
if castType.literal == 'Bool':
return pysmt.Or(args[0], args[1]), Type('Bool')
else: # type.literal == 'BitVector'
return pysmt.BVOr(args[0], args[1]), castType
elif isinstance(symbolicExpression, sympy.Xor):
return pysmt.BVXor(args[0], args[1]), castType
elif isinstance(symbolicExpression, sympy.Add):
return pysmt.Plus(args), castType
elif isinstance(symbolicExpression, sympy.Mul):
return pysmt.Times(args), castType
elif isinstance(symbolicExpression, sympy.Pow):
return pysmt.Pow(args[0], args[1]), castType
# TODO LATER: deal with missing modulo operator from pysmt
else:
if isinstance(symbolicExpression, sympy.Symbol):
symbolType = Variable.symbolTypes[symbolicExpression.name]
literal = symbolType.getTypeForSolver()
designator = symbolType.designatorExpr1
type = Type(literal, designator)
return Solver.__encodeTerminal(symbolicExpression, type), type
elif isinstance(symbolicExpression, sympy.Integer):
type = Type('Integer')
return Solver.__encodeTerminal(symbolicExpression, type), type
elif isinstance(symbolicExpression, sympy.Rational):
type = Type('Real')
return Solver.__encodeTerminal(symbolicExpression, type), type
elif isinstance(symbolicExpression, sympy.Float):
type = Type('Real')
return Solver.__encodeTerminal(symbolicExpression, type), type
else:
type = Type('Real')
return Solver.__encodeTerminal(symbolicExpression, type), type
def initialize(self, mdp, colors, hole_options, reward_name, okay_states,
target_states, threshold, relation):
logger.warning("This approach has been tested sparsely.")
prob0E, prob1A = stormpy.compute_prob01min_states(
mdp, okay_states, target_states)
sink_states = ~okay_states
assert len(mdp.initial_states) == 1
self.state_vars = [
smt.Symbol("p_{}".format(i), smt.REAL)
for i in range(mdp.nr_states)
]
self.state_prob1_vars = [
smt.Symbol("asure_{}".format(i)) for i in range(mdp.nr_states)
]
self.state_probpos_vars = [
smt.Symbol("x_{}".format(i)) for i in range(mdp.nr_states)
]
self.state_order_vars = [
smt.Symbol("r_{}".format(i), smt.REAL)
for i in range(mdp.nr_states)
]
self.option_vars = dict()
for h, opts in hole_options.items():
self.option_vars[h] = {
index: smt.Symbol("h_{}_{}".format(h, opt))
for index, opt in enumerate(opts)
}
self.transition_system = []
logger.debug("Obtain rewards if necessary")
rewards = mdp.reward_models[reward_name] if reward_name else None
if rewards:
assert not rewards.has_transition_rewards
state_rewards = rewards.has_state_rewards
action_rewards = rewards.has_state_action_rewards
logger.debug(
"Model has state rewards: {}, has state/action rewards {}".
format(state_rewards, action_rewards))
self.transition_system.append(
self.state_prob1_vars[mdp.initial_states[0]])
threshold_inequality, action_constraint_inequality = self._to_smt_relation(
relation) # TODO or GE
self.transition_system.append(
threshold_inequality(self.state_vars[mdp.initial_states[0]],
smt.Real(float(threshold))))
state_order_domain_constraint = smt.And([
smt.And(smt.GE(var, smt.Real(0)), smt.LE(var, smt.Real(1)))
for var in self.state_order_vars
])
self.transition_system.append(state_order_domain_constraint)
#TODO how to ensure that prob is zero if there is no path.
select_parameter_value_constraints = []
for h, opts in self.option_vars.items():
select_parameter_value_constraints.append(
smt.Or(ov for ov in opts.values()))
for i, opt1 in enumerate(opts.values()):
for opt2 in list(opts.values())[i + 1:]:
select_parameter_value_constraints.append(
smt.Not(smt.And(opt1, opt2)))
#logger.debug("Consistency: {}".format(smt.And(select_parameter_value_constraints)))
self.transition_system.append(
smt.And(select_parameter_value_constraints))
for state in mdp.states:
if sink_states.get(state.id):
assert rewards is None
self.transition_system.append(
smt.Equals(self.state_vars[state.id], smt.REAL(0)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(
smt.Not(self.state_prob1_vars[state.id]))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(
smt.Equals(self.state_order_vars[state.id], smt.Real(0)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
elif target_states.get(state.id):
self.transition_system.append(
smt.Equals(self.state_order_vars[state.id], smt.Real(1)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(self.state_prob1_vars[state.id])
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
if rewards is None:
self.transition_system.append(
smt.Equals(self.state_vars[state.id], smt.Real(1)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
else:
self.transition_system.append(
self.state_probpos_vars[state.id])
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(
smt.Equals(self.state_vars[state.id], smt.Real(0)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
else:
state_in_prob1A = False
state_in_prob0E = False
if prob0E.get(state.id):
state_in_prob0E = True
else:
self.transition_system.append(
smt.Equals(self.state_order_vars[state.id],
smt.Real(1)))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(
self.state_probpos_vars[state.id])
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
if rewards and not state_in_prob0E:
if prob1A.get(state.id):
self.transition_system.append(
self.state_prob1_vars[state.id])
logger.debug("Constraint: {}".format(
self.transition_system[-1]))
state_in_prob1A = True
for action in state.actions:
action_index = mdp.nondeterministic_choice_indices[
state.id] + action.id
#logger.debug("Action index: {}".format(action_index))
precondition = smt.And([
self.option_vars[hole][list(option)[0]] for hole,
option in colors.get(action_index, dict()).items()
])
reward_value = None
if rewards:
reward_const = (rewards.get_state_reward(
state.id) if state_rewards else 0.0) + (
rewards.get_state_action_reward(action_index)
if action_rewards else 0.0)
reward_value = smt.Real(reward_const)
act_constraint = action_constraint_inequality(
self.state_vars[state.id],
smt.Plus([
smt.Times(smt.Real(t.value()), self.
state_vars[t.column])
for t in action.transitions
] + [reward_value] if reward_value else []))
full_act_constraint = act_constraint
if state_in_prob0E:
if not rewards:
full_act_constraint = smt.And(
smt.Implies(self.state_probpos_vars[state.id],
act_constraint),
smt.Implies(
smt.Not(self.state_probpos_vars),
smt.Equals(self.state_vars[state.id],
smt.Real(0))))
self.transition_system.append(
smt.Implies(
precondition,
smt.Iff(
self.state_probpos_vars[state.id],
smt.Or([
smt.And(
self.state_probpos_vars[t.column],
smt.LT(
self.state_order_vars[
state.id],
self.state_order_vars[
t.column]))
for t in action.transitions
]))))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
if rewards and not state_in_prob1A:
# prob_one(state) <-> probpos AND for all succ prob_one(succ)
self.transition_system.append(
smt.Implies(
precondition,
smt.Iff(
self.state_prob1_vars[state.id],
smt.And([
self.state_prob1_vars[t.column]
for t in action.transitions
] + [self.state_probpos_vars[state.id]]))))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
self.transition_system.append(
smt.Implies(precondition, full_act_constraint))
#logger.debug("Constraint: {}".format(self.transition_system[-1]))
if rewards:
self.transition_system.append(
smt.And([smt.GE(sv, smt.Real(0)) for sv in self.state_vars]))
else:
self.transition_system.append(
smt.And([
smt.And(smt.GE(sv, smt.Real(0)), smt.LE(sv, smt.Real(1)))
for sv in self.state_vars
]))
#print(self.transition_system)
formula = smt.And(self.transition_system)
logger.info("Start SMT solver")
model = smt.get_model(formula)
if model:
logger.info("SAT: Found {}".format(model))
else:
logger.info("UNSAT.")