X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=week4.mdwn;h=e3f0fb956068b0e6c33b07ce9a8ef0e247b98d66;hp=e69832fd8e1cfeebe530a1ff7c119835a460c0ba;hb=792521cd3b2e337d425aadc7d8f09a2eab2eb391;hpb=6c76653f70358ec2dd633335e378bf8ef98fe215

diff --git a/week4.mdwn b/week4.mdwn
index e69832fd..e3f0fb95 100644
--- a/week4.mdwn
+++ b/week4.mdwn
@@ -6,11 +6,11 @@ A: That's easy: let `T` be an arbitrary term in the lambda calculus.  If
 `T` has a fixed point, then there exists some `X` such that `X <~~>
 TX` (that's what it means to *have* a fixed point).
 
-<pre>
-let W = \x.T(xx) in
-let X = WW in
-X = WW = (\x.T(xx))W = T(WW) = TX
-</pre>
+<pre><code>
+let L = \x. T (x x) in
+let X = L L in
+X &equiv; L L &equiv; (\x. T (x x)) L ~~> T (L L) &equiv; T X
+</code></pre>
 
 Please slow down and make sure that you understand what justified each
 of the equalities in the last line.
@@ -437,7 +437,7 @@ of the list multiplied to, because that would affect the answer you passed
 along to the continue-leftwards handler.
 
 A **version 5** list encodes the kind of fold operation we're envisaging here, in
-the same way that v3 (and [v4](/advanced/#v4)) lists encoded the simpler fold operation.
+the same way that v3 (and [v4](/advanced/#index1h1)) lists encoded the simpler fold operation.
 Roughly, the list `[5;4;3;2;1]` would look like this:
 
 
@@ -566,6 +566,6 @@ detail](http://okmij.org/ftp/Streams.html#enumerator-stream).
 				larger_computation
 
 3.	To extract tails efficiently, too, it'd be nice to fuse the apparatus developed
-	in these v5 lists with the ideas from [v4](/advanced/#v4) lists.
+	in these v5 lists with the ideas from [v4](/advanced/#index1h1) lists.
 	But that also is left as an exercise.