def main():
em = ExprManager()
smt = SmtEngine(em)
# Prove that for integers x and y:
# x > 0 AND y > 0 => 2x + y >= 3
integer = em.integerType()
x = em.mkVar("x", integer)
y = em.mkVar("y", integer)
zero = em.mkConst(Rational(0))
x_positive = em.mkExpr(CVC4.GT, x, zero)
y_positive = em.mkExpr(CVC4.GT, y, zero)
two = em.mkConst(Rational(2))
twox = em.mkExpr(CVC4.MULT, two, x)
twox_plus_y = em.mkExpr(CVC4.PLUS, twox, y)
three = em.mkConst(Rational(3))
twox_plus_y_geq_3 = em.mkExpr(CVC4.GEQ, twox_plus_y, three)
formula = Expr(em.mkExpr(CVC4.AND, x_positive,
y_positive)).impExpr(Expr(twox_plus_y_geq_3))
print "Checking validity of formula " + formula.toString() + " with CVC4."
print "CVC4 should report VALID."
print "Result from CVC4 is: " + smt.query(formula).toString()
return 0
def constant(cls, v, solver):
em = solver.getExprManager()
return cls(em.mkConst(Rational(Integer(str(v)))), solver)
def get_cvc4_const(em, float_val):
if float_val is None:
return None
f = Fraction(float_val).limit_denominator(100000000)
return em.mkConst(Rational(f.numerator, f.denominator))