def variables_to_numbers(effect, conditions):
new_effect_args = list(effect.args)
rename_map = {}
for i, arg in enumerate(effect.args):
if arg[0] == "?":
rename_map[arg] = i
new_effect_args[i] = i
new_effect = pddl.Atom(effect.predicate, new_effect_args)
# There are three possibilities for arguments in conditions:
# 1. They are variables that occur in the effect. In that case,
# they are replaced by the corresponding position in the
# effect, as indicated by the rename_map.
# 2. They are constants. In that case, the unifier must guarantee
# that they are matched appropriately. In that case, they are
# not modified (remain strings denoting objects).
# 3. They are variables that don't occur in the effect (are
# projected away). This is only allowed in projection rules.
# Such arguments are also not modified (remain "?x" strings).
new_conditions = []
for cond in conditions:
new_cond_args = [rename_map.get(arg, arg) for arg in cond.args]
new_conditions.append(pddl.Atom(cond.predicate, new_cond_args))
return new_effect, new_conditions
def condition_to_rule_body(parameters, condition):
for par in parameters:
yield pddl.Atom(par.type, [par.name])
if not isinstance(condition, pddl.Truth):
if isinstance(condition, pddl.ExistentialCondition):
for par in condition.parameters:
yield pddl.Atom(par.type, [par.name])
condition = condition.parts[0]
if isinstance(condition, pddl.Conjunction):
parts = condition.parts
else:
parts = (condition,)
for part in parts:
assert isinstance(part, pddl.Literal), "Condition not normalized"
if not part.negated:
yield part
def build_rules(self, rules):
axiom = self.owner
app_rule_head = get_axiom_predicate(axiom)
app_rule_body = list(condition_to_rule_body(axiom.parameters, self.condition))
rules.append((app_rule_body, app_rule_head))
eff_rule_head = pddl.Atom(axiom.name, [par.name for par in axiom.parameters])
eff_rule_body = [app_rule_head]
rules.append((eff_rule_body, eff_rule_head))
def _rename_duplicate_variables(self, atom, new_conditions):
used_variables = set()
for i, var_name in enumerate(atom.args):
if var_name[0] == "?":
if var_name in used_variables:
new_var_name = "%s@%d" % (var_name, len(new_conditions))
atom = atom.rename_variables({var_name: new_var_name})
new_conditions.append(
pddl.Atom("=", [var_name, new_var_name]))
else:
used_variables.add(var_name)
return atom
def substitute_complicated_goal(task):
goal = task.goal
if isinstance(goal, pddl.Literal):
return
elif isinstance(goal, pddl.Conjunction):
for item in goal.parts:
if not isinstance(item, pddl.Literal):
break
else:
return
new_axiom = task.add_axiom([], goal)
task.goal = pddl.Atom(new_axiom.name, new_axiom.parameters)
def remove_free_effect_variables(self):
"""Remove free effect variables like the variable Y in the rule
p(X, Y) :- q(X). This is done by introducing a new predicate
@object, setting it true for all objects, and translating the above
rule to p(X, Y) :- q(X), @object(Y).
After calling this, no new objects should be introduced!"""
# Note: This should never be necessary for typed domains.
# Leaving it in at the moment regardless.
must_add_predicate = False
for rule in self.rules:
eff_vars = get_variables([rule.effect])
cond_vars = get_variables(rule.conditions)
if not eff_vars.issubset(cond_vars):
must_add_predicate = True
eff_vars -= cond_vars
for var in eff_vars:
rule.add_condition(pddl.Atom("@object", [var]))
if must_add_predicate:
print("Unbound effect variables: Adding @object predicate.")
self.facts += [
Fact(pddl.Atom("@object", [obj])) for obj in self.objects
]
def convert_trivial_rules(self):
"""Convert rules with an empty condition into facts.
This must be called after bounding rule effects, so that rules with an
empty condition must necessarily have a variable-free effect.
Variable-free effects are the only ones for which a distinction between
ground and symbolic atoms is not necessary."""
must_delete_rules = []
for i, rule in enumerate(self.rules):
if not rule.conditions:
assert not get_variables([rule.effect])
self.add_fact(
pddl.Atom(rule.effect.predicate, rule.effect.args))
must_delete_rules.append(i)
if must_delete_rules:
print("Trivial rules: Converted to facts.")
for rule_no in must_delete_rules[::-1]:
del self.rules[rule_no]
def test_normalization():
prog = PrologProgram()
prog.add_fact(pddl.Atom("at", ["foo", "bar"]))
prog.add_fact(pddl.Atom("truck", ["bollerwagen"]))
prog.add_fact(pddl.Atom("truck", ["segway"]))
prog.add_rule(
Rule([pddl.Atom("truck", ["?X"])], pddl.Atom("at", ["?X", "?Y"])))
prog.add_rule(
Rule([pddl.Atom("truck", ["X"]),
pddl.Atom("location", ["?Y"])], pddl.Atom("at", ["?X", "?Y"])))
prog.add_rule(
Rule([pddl.Atom("truck", ["?X"]),
pddl.Atom("location", ["?Y"])], pddl.Atom("at", ["?X", "?X"])))
prog.add_rule(
Rule([pddl.Atom("p", ["?Y", "?Z", "?Y", "?Z"])],
pddl.Atom("q", ["?Y", "?Y"])))
prog.add_rule(Rule([], pddl.Atom("foo", [])))
prog.add_rule(Rule([], pddl.Atom("bar", ["X"])))
prog.normalize()
prog.dump()
def translate_typed_object(prog, obj, type_dict):
supertypes = type_dict[obj.type].supertype_names
for type_name in [obj.type] + supertypes:
prog.add_fact(pddl.Atom(type_name, [obj.name]))
def build_rules(self, rules):
rule_head_name = "@goal-reachable"
rule_head = pddl.Atom("@goal-reachable", [])
rule_body = list(condition_to_rule_body([], self.condition))
rules.append((rule_body, rule_head))
def get_axiom_predicate(axiom):
name = axiom
variables = [par.name for par in axiom.parameters]
if isinstance(axiom.condition, pddl.ExistentialCondition):
variables += [par.name for par in axiom.condition.parameters]
return pddl.Atom(name, variables)
def push(self, predicate, args):
self.num_pushes += 1
eff_tuple = (predicate, ) + tuple(args)
if eff_tuple not in self.enqueued:
self.enqueued.add(eff_tuple)
self.queue.append(pddl.Atom(predicate, list(args)))
def project_rule(rule, conditions, name_generator):
predicate = name_generator.next()
effect_variables = set(rule.effect.args) & get_variables(conditions)
effect = pddl.Atom(predicate, list(effect_variables))
projected_rule = Rule(conditions, effect)
return projected_rule
def add_rule(self, type, conditions, effect_vars):
effect = pddl.Atom(self.name_generator.next(), effect_vars)
rule = pddl_to_prolog.Rule(conditions, effect)
rule.type = type
self.result.append(rule)
return rule.effect