X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?a=blobdiff_plain;f=week1.mdwn;h=0207f0ceae92b3e0eafc4513fa279d8007de294e;hb=6ca041c08f7d5eccc1550af16de405c66fb23139;hp=5ae3e65f5c154f36a84432585178ed81bdb179ba;hpb=9452f39dcc5b7babde45142e2b24e3617813d6a6;p=lambda.git

diff --git a/week1.mdwn b/week1.mdwn
index 5ae3e65f..0207f0ce 100644
--- a/week1.mdwn
+++ b/week1.mdwn
@@ -39,8 +39,27 @@ Basics of Lambda Calculus
 
 The lambda calculus we'll be focusing on for the first part of the course has no types. (Some prefer to say it instead has a single type---but if you say that, you have to say that functions from this type to this type also belong to this type. Which is weird.)
 
+Here is its syntax:
+
+<blockquote>
+<strong>Variables</strong>: <code>x</code>, <code>y</code>, <code>z</code>...
+</blockquote>
+
+Each variable is an expression. For any expressions M and N and variable a, the following are also expressions:
+
+<blockquote>
+<strong>Abstract</strong>: <code>(&lambda;a M)</code>
+</blockquote>
+
+We'll tend to write <code>(&lambda;a M)</code> as just `(\a M)`, so we don't have to write out the markup code for the <code>&lambda;</code>. You can yourself write <code>(&lambda;a M)</code> or `(\a M)` or `(lambda a M)`.
+
+<blockquote>
+<strong>Application</strong>: <code>(M N)</code>
+</blockquote>
+
 Some authors reserve the term "term" for just variables and abstracts. We'll probably just say "term" and "expression" indiscriminately for expressions of any of these three forms.
 
+<div>
 Examples of expressions:
 
 	x
@@ -52,6 +71,8 @@ Examples of expressions:
 	(x (\x x))
 	((\x (x x)) (\x (x x)))
 
+</div>
+
 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: