Z3 无法通过测试证明两个使用 Kleene 代数的简单程序之间的等价性，但 Mathematica 和 Reduce 能够

Question

我们这里的问题是表明

在测试中使用 Kleene 代数。

在 b 的值由 p 保留的情况下，我们有交换条件 bp = pb;两个程序之间的等价性简化为等式

在 b 的值不被 p 保留的情况下，我们有交换性条件 pc = cp；两个程序之间的等价性简化为等式

我正在尝试使用以下 SMT-LIB 代码证明第一个等式

(declare-sort S)
(declare-fun sum (S S) S)
(declare-fun mult (S S) S)
(declare-fun neg (S) S)
(assert (forall ((x S) (y S) (z S)) (= (mult x (sum y z)) (sum (mult x y) (mult y z)))   ) )
(assert (forall ((x S) (y S) (z S)) (= (mult (sum y z) x) (sum (mult y x) (mult z x)))   ) )
(assert (forall ((x S) (y S) (z S)) (= (mult x (mult y z)) (mult (mult x y) z))    ))
(check-sat)
(push)
(declare-fun b () S)
(declare-fun p () S)
(declare-fun q () S)
(declare-fun r () S)
(assert (= (mult b p) (mult p b)) )
(check-sat)
(pop)

但我正在获取超时；也就是说Z3不能满足交换条件bp = pb。请在线运行此示例here .

Z3 无法证明这些方程，但 Mathematica 和 Reduce 可以。 Z3 没有定理证明器那么强大。你同意吗？

Answer 1

使用 Z3 和以下 SMT-LIB 代码证明了第一个方程

(declare-sort S)
(declare-fun e () S)
(declare-fun O () S)
(declare-fun mult (S S) S)
(declare-fun sum  (S S) S)
(declare-fun leq (S S) Bool)
(declare-fun negation (S) S)
(declare-fun test (S) Bool)
(assert (forall ((x S) (y S))  (= (sum x y) (sum y x ))))
(assert (forall ((x S) (y S) (z S)) (= (sum (sum x y) z) (sum x (sum y z)))))
(assert (forall ((x S)) (= (sum O x)  x)))
(assert (forall ((x S)) (= (sum x x)  x)))
(assert (forall ((x S) (y S) (z S)) (= (mult (mult x y) z) (mult x (mult y z)))))
(assert (forall ((x S)) (= (mult e x)  x)))
(assert (forall ((x S)) (= (mult x e)  x)))
(assert (forall ((x S) (y S) (z S)) (= (mult x (sum y z) ) (sum   (mult x y) (mult x z)))))
(assert (forall ((x S) (y S) (z S)) (= (mult (sum x y) z ) (sum   (mult x z) (mult y z)))))
(assert (forall ((x S)) (= (mult x O)  O)))
(assert (forall ((x S)) (= (mult O x)  O)))
(assert (forall ((x S) (y S))  (= (leq x y) (= (sum x y) y))))
(assert (forall ((x S) (y S)) (=> (and (test x) (test y) )  (= (mult x y) (mult y x))) ) )
(assert (forall ((x S)) (=> (test x) (= (sum x (negation x)) e)  ))) 
(assert (forall ((x S)) (=> (test x) (= (mult x (negation x)) O)  ))) 
(check-sat)

(push)
;; bpq + b`pr = p(bq + b`r)
(declare-fun b () S)
(declare-fun p () S)
(declare-fun q () S)
(declare-fun r () S)
(assert (=> (test b) (= (mult p b) (mult b p))   )) 
(assert  (=> (test b) (= (mult p (negation b)) (mult (negation b) p)))) 
(check-sat)
(assert (not (=> (test b) (= (sum (mult b (mult p q)) (mult (negation b) (mult p r) )) 
                                                               (mult p (sum (mult b q) (mult (negation b) r)))))      ) ) 
(check-sat)
(pop)
(echo "Proved: bpq + b`pr = p(bq + b`r)")

输出是

sat
sat
unsat
Proved: bpq + b`pr = p(bq + b`r)

请在线运行此证明here