对于下面的问题，解决方案存在，但z3说UNSAT。
(set-logic QF_UFNRA)
(declare-fun a () Real)
(declare-fun b () Real)
(declare-fun c () Real)
(declare-fun d () Real)
(declare-fun e () Real)
(declare-fun f () Real)
(declare-fun g () Real)
(declare-fun h () Real)
(assert (and (<= a 1.0) (> a 0.0)))
(assert (and (<= b 1.0) (> b 0.0)))
(assert (and (<= c 1.0) (> c 0.0)))
(assert (and (<= d 1.0) (> d 0.0)))
(assert (and (<= e 1.0) (>= e 0.0)))
(assert (and (<= f 1.0) (>= f 0.0)))
(assert (and (<= g 1.0) (>= g 0.0)))
(assert (and (<= h 1.0) (>= h 0.0)))
(assert (= (* (+ a b) (+ a c)) a))
(assert (= (* (+ a b) (+ b d)) b))
(assert (= (* (+ a c) (+ c d)) c))
(assert (= (* (+ b d) (+ c d)) d))
(assert (= (+ a b c d e f g h) 1.0))
(check-sat)
有效的解决方案：
a = 1/12, b = 1/4, c = 1/6, d = 1/2, e = f = g = h = 0
我无法弄清楚为什么z3表示不满意。
z3版本为z3-4.3.0-x64。