您能告诉我如何拆分 unsat 核心的子句吗?
这是问题2,关于找到未饱和的核心后,我将尝试再次寻找。
您想告诉我如何做到这一点吗?
非常感谢。
如何拆分以下子句
`and` (`or` (`<=_int` 1002 x1) (`<=_int` 1000 x1)) (`and` (`or` (`<=_int` 0 (`+_int` x2 (`*_int` -1003 x1))) (`<=_int` 0 (`+_int` x2 (`*_int` -1230 x1)))) (`and` (`or` (`<=_int` 0 (`+_int` x3 (`*_int` -1999 x2)))
关于问题2,
cout<<s.check(3,assumptions)<<endl;
expr_vector core = s.unsat_core();
................
expr assumptions2[2] = {p1,p3};
cout<<"check next"<<s.check(2,assumptions2)<<endl;
expr_vector core1 = s.unsat_core();
for(unsigned int k=0;k<core1.size();++k){
cout<<"New core size "<<k<<endl;
cout<<"New unsat core "<<core1[k]<<endl;
}
再次调用unsat core函数,它不能再次给出unsat core。
非常感谢。
我不确定我是否理解你的问题。看来你有一个形式的断言(and c1 (and c2 c3))
,并且您想要跟踪c1
, c2
and c3
单独。
在 Z3 中,我们使用答案文字来跟踪断言。答案文字本质上是一个新的布尔值,用于跟踪断言。也就是说,断言是否被(Z3)使用来显示整组断言的不可满足性。例如,如果我们想跟踪断言F
,我们创建一个新的布尔变量p
并断言p implies F
。然后,我们提供p
作为 check 方法的参数。
If F
是一个大合词,我们想要单独跟踪它的元素,我们应该提取它的元素并为每个元素创建一个答案文字。这是实现这一技巧的完整示例。您可以通过将其包含在example.cpp
Z3 发行版中包含的文件。请注意,您必须包括#include<vector>
.
/**
\brief Unsat core example 2
*/
void unsat_core_example2() {
std::cout << "unsat core example 2\n";
context c;
// The answer literal mechanism, described in the previous example,
// tracks assertions. An assertion can be a complicated
// formula containing containing the conjunction of many subformulas.
expr p1 = c.bool_const("p1");
expr x = c.int_const("x");
expr y = c.int_const("y");
solver s(c);
expr F = x > 10 && y > x && y < 5 && y > 0;
s.add(implies(p1, F));
expr assumptions[1] = { p1 };
std::cout << s.check(1, assumptions) << "\n";
expr_vector core = s.unsat_core();
std::cout << core << "\n";
std::cout << "size: " << core.size() << "\n";
for (unsigned i = 0; i < core.size(); i++) {
std::cout << core[i] << "\n";
}
// The core is not very informative, since p1 is tracking the formula F
// that is a conjunction of subformulas.
// Now, we use the following piece of code to break this conjunction
// into individual subformulas. First, we flat the conjunctions by
// using the method simplify.
std::vector<expr> qs; // auxiliary vector used to store new answer literals.
assert(F.is_app()); // I'm assuming F is an application.
if (F.decl().decl_kind() == Z3_OP_AND) {
// F is a conjunction
std::cout << "F num. args (before simplify): " << F.num_args() << "\n";
F = F.simplify();
std::cout << "F num. args (after simplify): " << F.num_args() << "\n";
for (unsigned i = 0; i < F.num_args(); i++) {
std::cout << "Creating answer literal q" << i << " for " << F.arg(i) << "\n";
std::stringstream qname; qname << "q" << i;
expr qi = c.bool_const(qname.str().c_str()); // create a new answer literal
s.add(implies(qi, F.arg(i)));
qs.push_back(qi);
}
}
// The solver s already contains p1 => F
// To disable F, we add (not p1) as an additional assumption
qs.push_back(!p1);
std::cout << s.check(qs.size(), &qs[0]) << "\n";
expr_vector core2 = s.unsat_core();
std::cout << core2 << "\n";
std::cout << "size: " << core2.size() << "\n";
for (unsigned i = 0; i < core2.size(); i++) {
std::cout << core2[i] << "\n";
}
}
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