diff --git a/doc/manual/source/the-model-file.rst b/doc/manual/source/the-model-file.rst
index a1437afa684aa86ec60358986a6dd9482851f633..c79b19371e85ee84ef1f42863d36cd0283c53fe7 100644
--- a/doc/manual/source/the-model-file.rst
+++ b/doc/manual/source/the-model-file.rst
@@ -3878,7 +3878,7 @@ speed-up on large models.
        .. math::
              LB = X   &\Rightarrow   F(X)>0\\
  
-             LB\leq X \leq UB &\Rightarrow   F(X)=0\\
+             LB < X < UB &\Rightarrow   F(X)=0\\
 
              X =UB &\Rightarrow   F(X)<0.