diff --git a/extras/courses.md b/extras/courses.md
index 820ba8a..1f1594e 100644
--- a/extras/courses.md
+++ b/extras/courses.md
@@ -129,6 +129,7 @@ Courses | Duration | Effort
 ### Computer Graphics
 
 ### Artificial Intelligence
+:-- | :--: | :--:
 [Discrete Optimization](https://www.coursera.org/course/optimization)| 9 weeks | 10-20 hours/week
 
 ### Machine Learning