CODEWITHSUNDEEP
pythonz3z3py
florian.isopp
florian.isopp

Reputation: 862

Z3Py How to get values after solve() function

Could someone explain how to access the result values of the equation variables, when using the solve() function of the https://pypi.org/project/z3-solver/.

x, y = BitVecs('x y', 32)
solve(x + y == 2, x > 0, y > 0)

I have tried following to no avail

m = solve(x + y == 2, x > 0, y > 0)
print(m.x)

Mind, in this scenario we do not want to use the Solver

s = Solver()
s.add(And(x + y == 2, x > 0, y > 0))
s.check()
m = s.model()
print(m[x], m[y])

Upvotes: 0

Views: 1496

Answers (1)

Axel Kemper
Axel Kemper

Reputation: 11322

There seems to be no direct way. Function solve() prints the found solution but does not return the model.

The definition of solve() in file z3.py:

def solve(*args, **keywords):
    """Solve the constraints `*args`.

    This is a simple function for creating demonstrations. It creates a solver,
    configure it using the options in `keywords`, adds the constraints
    in `args`, and invokes check.

    >>> a = Int('a')
    >>> solve(a > 0, a < 2)
    [a = 1]
    """
    s = Solver()
    s.set(**keywords)
    s.add(*args)
    if keywords.get('show', False):
        print(s)
    r = s.check()
    if r == unsat:
        print("no solution")
    elif r == unknown:
        print("failed to solve")
        try:
            print(s.model())
        except Z3Exception:
            return
    else:
        print(s.model())

So, solve() is just a wrapper function. It creates a Solver() and does not expose the resulting model to access the variables.

Upvotes: 2

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