def solve(t):
"""Solve the given goal using Z3."""
s = z3.Solver()
# First strip foralls from t.
while Term.is_all(t):
t = t.arg.subst_bound(Var(t.arg.var_name, t.arg.var_T))
s.add(z3.Not(convert(t)))
return str(s.check()) == 'unsat'
def strip_all_implies(t, names):
"""Given a term of the form
!x_1 ... x_k. A_1 --> ... --> A_n --> C.
Return the triple ([v_1, ..., v_k], [A_1, ... A_n], C), where
v_1, ..., v_k are new variables with the given names, and
A_1, ..., A_n, C are the body of the input term, with bound variables
substituted for v_1, ..., v_k.
"""
if Term.is_all(t):
assert len(names) > 0, "strip_all_implies: not enough names input."
assert isinstance(names[0],
str), "strip_all_implies: names must be strings."
v = Var(names[0], t.arg.var_T)
vars, As, C = strip_all_implies(t.arg.subst_bound(v), names[1:])
return ([v] + vars, As, C)
else:
assert len(names) == 0, "strip_all_implies: too many names input."
As, C = t.strip_implies()
return ([], As, C)