diff --git a/steffen-schuldenzucker.md b/steffen-schuldenzucker.md
index 3e53111cc..2c1e7aa8e 100644
--- a/steffen-schuldenzucker.md
+++ b/steffen-schuldenzucker.md
@@ -28,6 +28,10 @@
   - [[category theory]]
     - [[steffen]] did some during earlier studies -- perhaps it was too early. Later in studies it came very handy.
     - also used it in [[haskell]]
+    - it's useful because you can map betwen categories
+      - had algebraic data types
+      - wanted to do probability theory
+      - you can map between the two
 
 
 [//begin]: # "Autogenerated link references for markdown compatibility"