X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=topics%2Fweek3_combinatory_logic.mdwn;h=0ddb4469254d3c4faeae7ce1cb02d249eac0c2a8;hp=c15424f9951ec1348b11839313dbccef19b9cac5;hb=82981fcd3e99f6f2927c2a958340800fbd842d9c;hpb=6f90fa9381988785d23d45beae679a7acfd3aefa

diff --git a/topics/week3_combinatory_logic.mdwn b/topics/week3_combinatory_logic.mdwn
index c15424f9..0ddb4469 100644
--- a/topics/week3_combinatory_logic.mdwn
+++ b/topics/week3_combinatory_logic.mdwn
@@ -175,6 +175,17 @@ used to establish a correspondence between two natural language grammars, one
 of which is based on lambda-like abstraction, the other of which is based on
 Combinatory Logic-like manipulations.
 
+[WARNING: the mapping from the lambda calculus to Combinatory Logic
+has been changed since the class in which it was presented.  It now
+matches the presentation in Barendregt.  The revised version is
+cleaner, and more elegant.  If you spent a lot of time working to
+understand the original version, there's good news and bad news.  The
+bad news is that things have changed.  The good news is that the new
+version described the same mapping as before, but does it in a cleaner
+way.  That is, the CL term that a given lambda term maps onto hasn't
+changed, only the details of how that CL term gets computed.  Sorry if
+the changeup causes any distress!]
+
 In order to establish the correspondence, we need to get a bit more
 official about what counts as an expression in CL.  We'll endow CL
 with an infinite stock of variable symbols, just like the lambda