如何从 z3py 中的 Z3 Solver object 中获取现有约束？

Question

例如，我想从 s 中获取现有约束并进入优化 object。

from z3 import *

a = Int('a')
x = Int('x')
b = Array('I', IntSort(), IntSort())
s = Solver()

s.add(a >= 0)
s.add(x == 0)
s.add(Select(b, 0) == 10)
s.add(Select(b, x) >= a)

opt = Optimize()
opt.add(s.constraints)

obj1 = opt.maximize(a)
obj2 = opt.minimize(a)

opt.set('priority', 'box')   # Setting Boxed Multi-Objective Optimization

is_sat = opt.check()
assert is_sat

print("Max(a): " + str(obj1.value()))
print("Min(a): " + str(obj2.value()))

那么结果会是这样的。

~$ python test.py 
Max(a): 10
Min(a): 0

Answer 1

如果想要获得添加到Solver （或Optimize ）实例的所有约束的向量，可以使用方法assertions() ：

 | assertions(self) | Return an AST vector containing all added constraints. | | >>> s = Solver() | >>> s.assertions() | [] | >>> a = Int('a') | >>> s.add(a > 0) | >>> s.add(a < 10) | >>> s.assertions() | [a > 0, a < 10]

[来源：z3 文档]

例子：

from z3 import *

a = Int('a')
x = Int('x')
b = Array('I', IntSort(), IntSort())

s = Solver()

s.add(a >= 0)
s.add(x == 0)
s.add(Select(b, 0) == 10)
s.add(Select(b, x) >= a)

opt = Optimize()

opt.add(s.assertions())

obj1 = opt.maximize(a)
obj2 = opt.minimize(a)

opt.set('priority', 'box')

is_sat = opt.check()
assert is_sat

print("Max(a): " + str(obj1.value()))
print("Min(a): " + str(obj2.value()))

Output：

~$ python test.py 
Max(a): 10
Min(a): 0