XGitUrl: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=week1.mdwn;h=cacb73fc61c4d49d4b4afa2cf2c4df05d533447e;hp=f449ed49e8663878d519af2e55ddea82fd44603a;hb=9a4224ba2c49f246262dd164b7a9102c3ad64fd5;hpb=c3468a4b473b3cff1028e1c3d652719595d32fd3
diff git a/week1.mdwn b/week1.mdwn
index f449ed49..cacb73fc 100644
 a/week1.mdwn
+++ b/week1.mdwn
@@ 57,18 +57,7 @@ We'll tend to write (λa M)
as just `(\a M)`, so we don't hav
Application: (M N)
Some authors reserve the term "term" for just variables and abstracts. We won't *participate* in that convention; we'll probably just say "term" and "expression" indiscriminately for expressions of any of these three forms.

Examples of expressions:

 x
 (y x)
 (x x)
 (\x y)
 (\x x)
 (\x (\y x))
 (x (\x x))
 ((\x (x x)) (\x (x x)))
+Some authors reserve the term "term" for just variables and abstracts. We won't participate in that convention; we'll probably just say "term" and "expression" indiscriminately for expressions of any of these three forms.
The *lambda* calculus has an associated proof theory. For now, we can regard the proof theory as having just one rule, called the rule of **betareduction** or "betacontraction". Suppose you have some expression of the form: