From a9fda81d0350fa586f9ef12c10309adab65847b0 Mon Sep 17 00:00:00 2001
From: Murphy Berzish <murphy.berzish@gmail.com>
Date: Thu, 18 Jan 2018 17:53:42 -0500
Subject: [PATCH] check polarity

---
 src/smt/theory_str.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/smt/theory_str.cpp b/src/smt/theory_str.cpp
index 1f84b5faf..dceb17a06 100644
--- a/src/smt/theory_str.cpp
+++ b/src/smt/theory_str.cpp
@@ -9856,7 +9856,7 @@ namespace smt {
                             if ( (current_assignment == l_true && !assumption.get_polarity())
                                     || (current_assignment == l_false && assumption.get_polarity())) {
                                 // invert sense
-                                NOT_IMPLEMENTED_YET();
+                                zero_solution = !zero_solution;
                             }
 
                             if (zero_solution) {