X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=topics%2Fweek2_lambda_intro.mdwn;h=d002abf8da0287a592c2286749f95f22a2326ab6;hp=3718d317134eab8993ec3684dc644e4bae948ca4;hb=4ab26de71d9694f5a65a80cd87d11734cc6aa02b;hpb=a9aa00567a448746beece0fd605b29fadb64686c

diff --git a/topics/week2_lambda_intro.mdwn b/topics/week2_lambda_intro.mdwn
index 3718d317..d002abf8 100644
--- a/topics/week2_lambda_intro.mdwn
+++ b/topics/week2_lambda_intro.mdwn
@@ -228,7 +228,12 @@ abbreviates:
 
     ((\x (\y (x y))) x)
 
-We didn't have to insert any parentheses around the inner body of `\y. (x y)` because they were already there.
+The outermost parentheses were added because we have an application. `(\x. \y.
+...)` became `(\x (\y. ...))` because of the rule for dots. We didn't have to
+insert any parentheses around the inner body of `\y. (x y)` because they were
+already there. That is, in expressions of the form `\y. (...)`, the dot abbreviates
+nothing. It's harmless to write such a dot, though, and it can be conceptually
+helpful especially in light of the next convention...
 
 
 **Merging lambdas** An expression of the form `(\x (\y M))`, or equivalently, `(\x. \y. M)`, can be abbreviated as:
@@ -270,7 +275,7 @@ For some lambda terms, it is easy to see what function they represent:
 simply returns `M`: `((\x x) M) ~~> M`.
 
 > `(\x (x x))` duplicates its argument (applies it to itself):
-`((\x (x x)) M) ~~> (M M)` <!-- **M** or &omega;; W is \uv.uvv -->
+`((\x (x x)) M) ~~> (M M)` <!-- **M** or &omega;; W is \uv.uvv, L is \uv.u(vv) -->
 
 > `(\x (\y (y x)))` reorders its two arguments:
 `(((\x  (\y (y x))) M) N) ~~> (N M)` <!-- **T**; C is \uvx.uxv -->