diff --git a/00_Introduction.lhs b/00_Introduction.lhs
index b4720ad..1ef0d29 100644
--- a/00_Introduction.lhs
+++ b/00_Introduction.lhs
@@ -222,6 +222,7 @@ A -> C [label="h'\n=g'∘f\n=g∘f'"]
### Examples
Which can be a valid category by choosing ∘ appropriately?
+The identity morphisms are assumed.
A[label="★"]
@@ -251,8 +252,11 @@ A -> C
-A -> B [constraint=false]
-B -> C [constraint=false]
+A[pos="0,0"]
+B[pos="2,0"]
+C[pos="1,-1"]
+A -> B
+B -> C
B -> A
C -> A