z3 with some improvements:
-
BitVec
:- Change the right shift operation to be logical instead of arithmetic
-
Add the
ByteVec
class -
Add some helper methods for solving:
easy_solve
find_all_solutions
easy_prove
-
Add some helper methods for optimizing:
maximize
minimize
-
Add some helper functions for z3 variables/constants:
BoolToInt
Sgn
TruncDiv
These features were first provided by z4, before z3 included these features. They have now been removed from z4.
-
BoolRef
: -
Helper functions:
Abs
cf08cdf
Install with pip install z4-solver
.
import z4
a, b = z4.Ints("a b")
print(z4.easy_solve([a <= 10, b <= 10, a + b == 15]))
Output:
[b = 5, a = 10]
import z4
a, b = z4.Ints("a b")
print(*z4.find_all_solutions([a <= 10, b <= 10, a + b == 15]), sep="\n")
Output:
[b = 5, a = 10]
[b = 6, a = 9]
[b = 7, a = 8]
[b = 8, a = 7]
[b = 9, a = 6]
[b = 10, a = 5]
Let's try and prove that 2 * a >= a
for all integers a
:
import z4
a = z4.Int("a")
print(z4.easy_prove(2 * a >= a))
Output
Traceback (most recent call last):
...
z4.Z3CounterExample: [a = -1]
This isn't true so we get an exception with the counter-example a = -1
. Of course 2 * -1 = -2
which is less than -1
.
Let's try again with the assumption that a
must be non-negative:
print(z4.easy_prove(z4.Implies(a >= 0, 2 * a >= a)))
Output:
True