X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?a=blobdiff_plain;f=topics%2Fweek3_what_is_computation.mdwn;h=48d231dd4d222048b5d810500ad66de0d4526417;hb=7acee0fbdbcefcac2ebf8e27e8b0312767dc575e;hp=0c9c5c5431a09124fabcf1b9ec1869a283dd5e59;hpb=63156a22b401c0fdbe7a6b98ac0e402977ec8a5b;p=lambda.git
diff --git a/topics/week3_what_is_computation.mdwn b/topics/week3_what_is_computation.mdwn
index 0c9c5c54..48d231dd 100644
--- a/topics/week3_what_is_computation.mdwn
+++ b/topics/week3_what_is_computation.mdwn
@@ -135,11 +135,13 @@ pathological examples where the results do not align so well:
(\x. x x) (\x. x x) ~~> (\x. x x) (\x. x x) ~~> (\x. x x) (\x. x x) ~~> ...
In this example, reduction returns the exact same lambda term. There
-is no simplification at all.
+is no simplification at all. (As we mentioned in class, the term `(\x. x x)` is often referred to in these discussions as (little) ω or "omega", or sometimes **M**; and its self-application ω ω
, displayed above, is called (big) Ω or "Omega".)
+
+Even worse, consider this term:
(\x. x x x) (\x. x x x) ~~> (\x. x x x) (\x. x x x) (\x. x x x) ~~> ...
-Even worse, in this case, the "reduced" form is longer and more
+Here, the "reduced" form is longer and more
complex by any reasonable measure.
We may have to settle for the idea that a well-chosen reduction system