def helper(f, used, substs):
if is_variable(f):
if f in substs: return substs[f]
else: return f
if is_quantified(f):
# does this quantifier use a variable that is already used?
clashing = (used & set(f.vars)) # set intersection
if len(clashing) > 0:
for var in clashing:
existing = used.union(*list(map(vars, substs.values())))
# rename any clashing variable
var2 = variant(var, existing)
substs[var] = var2
used.update(f.vars)
arg = helper(f.args[0], used, substs)
return Quantifier(f.op,
[subst(substs, x) for x in f.vars],
*[subst(substs, x) for x in f.args])
else:
used.update(f.vars)
arg = helper(f.args[0], used, substs)
return Quantifier(f.op, f.vars, arg)
else:
return Expr(f.op, *[helper(x, used, substs) for x in f.args])
def formula_to_rst(f):
""" Convert a FOL formula to an RST tree. """
get_log().debug(str(f))
if f.op == OP_AND:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Conjunction", None, *msgs)
# test = lambda x: (x.op == '&' or x.op == '|')
# if any(map(test, f.args)):
# m.marker = ', and'
# else:
m.marker = "and"
return m
if f.op == OP_OR:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Disjunction", None, *msgs)
# test = lambda x: (x.op != 'forall' and
# x.op != 'exists')
# if any(map(test, f.args)):
# m.marker = ', or'
# else:
m.marker = "or"
return m
if f.op == OP_IMPLIES:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Imply", msgs[0], msgs[1])
return m
if f.op == OP_IMPLIED_BY:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Imply", msgs[1], msgs[0])
return m
if f.op == OP_EQUIVALENT:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Equivalent", msgs[0], msgs[1])
return m
if f.op == OP_EQUALS:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Equality", msgs[0], *msgs[1:])
return m
if f.op == OP_NOTEQUALS:
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Inequality", msgs[0], *msgs[1:])
return m
if f.op == OP_FORALL:
vars = [formula_to_rst(x) for x in f.vars]
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Quantifier", vars, *msgs)
m.marker = "for all"
return m
if f.op == OP_EXISTS:
vars = [formula_to_rst(x) for x in f.vars]
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Quantifier", vars, *msgs)
if len(f.vars) == 1:
m.marker = "there exists"
else:
m.marker = "there exist"
return m
if f.op == OP_NOT and is_predicate(f.args[0]):
get_log().debug("negated predicate: " + str(f))
arg = f.args[0]
m = PredicateMsg(arg, *[formula_to_rst(x) for x in arg.args])
m._features = {"NEGATED": "true"}
return m
if f.op == OP_NOT and is_variable(f.args[0]):
get_log().debug("negated variable: " + str(f))
arg = f.args[0]
m = NounPhrase(PlaceHolder(arg.op), Word("not", "DETERMINER"))
return m
if f.op == OP_NOT:
get_log().debug("negated formula: " + str(f))
msgs = [formula_to_rst(x) for x in f.args]
m = Message("Negation", msgs[0], *msgs[1:])
m.marker = "it is not the case that"
return m
if is_predicate(f):
get_log().debug("predicate: " + str(f))
return PredicateMsg(f, *[formula_to_rst(x) for x in f.args])
if is_function(f):
get_log().debug("function: " + str(f))
return PlaceHolder(f.op, PredicateMsg(f, *[formula_to_rst(x) for x in f.args]))
else:
get_log().debug("None: " + repr(f))
return PredicateMsg(f)