week1: tweaks

Signed-off-by: Jim Pryor <profjim@jimpryor.net>

diff --git a/week1.mdwn b/week1.mdwn
index cacb73f..af079ed 100644 (file)
--- a/week1.mdwn
+++ b/week1.mdwn
@@ -59,6 +59,8 @@ We'll tend to write <code>(&lambda;a M)</code> as just `(\a M)`, so we don't hav
 
 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.
 
+Samples of expressions
+
 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 **beta-reduction** or "beta-contraction". Suppose you have some expression of the form:
 
        ((\a M) N)