add anchor #deriving-y

diff --git a/topics/week4_fixed_point_combinators.mdwn b/topics/week4_fixed_point_combinators.mdwn
index b20212d..1ed99d2 100644 (file)
--- a/topics/week4_fixed_point_combinators.mdwn
+++ b/topics/week4_fixed_point_combinators.mdwn
@@ -293,6 +293,7 @@ The strategy we will present will turn out to be a general way of
 finding a fixed point for any lambda term.
 
 
+<a id=deriving-y></a>
 ## Deriving Y, a fixed point combinator ##
 
 How shall we begin?  Well, we need to find an argument to supply to