From 46354da45e90d803a324be20b6613a8700349a1c Mon Sep 17 00:00:00 2001 From: Jim Pryor Date: Wed, 15 Sep 2010 23:21:55 -0400 Subject: [PATCH 1/1] week1: fix markup processing? Signed-off-by: Jim Pryor --- week1.mdwn | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) diff --git a/week1.mdwn b/week1.mdwn index 5eba0211..1bc2309e 100644 --- a/week1.mdwn +++ b/week1.mdwn @@ -285,18 +285,16 @@ It's possible to enhance the lambda calculus so that functions do get identified It's often said that dynamic systems are distinguished because they are the ones in which **order matters**. However, there are many ways in which order can matter. If we have a trivalent boolean system, for example---easily had in a purely functional calculus---we might choose to give a truth-table like this for "and": -

-true and true   = true
-true and true   = true
-true and *      = *
-true and false  = false
-* and true      = *
-* and *         = *
-* and false     = *
-false and true  = false
-false and *     = false
-false and false = false
-
+ true and true = true + true and true = true + true and * = * + true and false = false + * and true = * + * and * = * + * and false = * + false and true = false + false and * = false + false and false = false And then we'd notice that `* and false` has a different intepretation than `false and *`. (The same phenomenon is already present with the material conditional in bivalent logics; but seeing that a non-symmetric semantics for `and` is available even for functional languages is instructive.) @@ -674,7 +672,7 @@ Here's how it looks to say the same thing in various of these languages. and there's no more mutation going on there than there is in: 
∀x. (F x or ∀x (not (F x)))
-
+ When a previously-bound variable is rebound in the way we see here, that's called **shadowing**: the outer binding is shadowed during the scope of the inner binding. -- 2.11.0