notes for week 4

diff --git a/assignment3.mdwn b/assignment3.mdwn
index 4e3c4f3..f93afd6 100644 (file)
--- a/assignment3.mdwn
+++ b/assignment3.mdwn
@@ -4,7 +4,7 @@ Assignment 3
 Once again, the lambda evaluator will make working through this
 assignment much faster and more secure.
 
 Once again, the lambda evaluator will make working through this
 assignment much faster and more secure.
 

-*Writing recursive functions on version 1 style lists*
+##Writing recursive functions on version 1 style lists##

 
 Recall that version 1 style lists are constructed like this:
 
 
 Recall that version 1 style lists are constructed like this:
 


@@ -46,7 +46,7 @@ eq 3 3
 
 Then `length mylist` evaluates to 3.
 
 
 Then `length mylist` evaluates to 3.
 

-1. What does `head (tail (tail mylist))` evaluate to?
+1. Warm-up: What does `head (tail (tail mylist))` evaluate to?

 
 2. Using the `length` function as a model, and using the predecessor
 function, write a function that computes factorials.  (Recall that n!,
 
 2. Using the `length` function as a model, and using the predecessor
 function, write a function that computes factorials.  (Recall that n!,


@@ -65,9 +65,17 @@ same length.  That is,
 
      listLenEq mylist (makeList meh (makeList meh nil))) ~~> false
 
 
      listLenEq mylist (makeList meh (makeList meh nil))) ~~> false
 

-

 4. Now write the same function, but don't use the length function (hint: use `leq` as a model).
 
 4. Now write the same function, but don't use the length function (hint: use `leq` as a model).
 

+##Trees##
+
+Since we'll be working with linguistic objects, let's approximate
+trees as follows: a tree is a version 1 list
+a Church number is a tree, and 
+if A and B are trees, then (make-pair A B) is a tree.
+
+
+

 
 [The following should be correct, but won't run in my browser:
 
 
 [The following should be correct, but won't run in my browser: