From 7b80daef951f850ecab4e539d103607c7808d73b Mon Sep 17 00:00:00 2001
From: Jim Pryor
Date: Mon, 22 Nov 2010 05:50:57 -0500
Subject: [PATCH] assign7 tweak
Signed-off-by: Jim Pryor
---
assignment7.mdwn | 2 +-
hints/assignment_7_hint_1.mdwn | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/assignment7.mdwn b/assignment7.mdwn
index 5db178b2..d6cb6813 100644
--- a/assignment7.mdwn
+++ b/assignment7.mdwn
@@ -19,7 +19,7 @@
* You don't need to re-express the epistemic modality part of their semantics, just their treatment of extensional predicate logic. Though extra credit if you want to do the whole thing.
- * You'll want to use the implementation of "implicitly represented" mutable variables that we discussed at the end of this week's meeting, or the "state monad" Chris presented, which is a simple version of the former.
+ * You'll want to use "implicitly represented" mutable variables, or a State monad.
* Here are some [hints](/hints/assignment_7_hint_1).
diff --git a/hints/assignment_7_hint_1.mdwn b/hints/assignment_7_hint_1.mdwn
index ac15e19b..a68c826a 100644
--- a/hints/assignment_7_hint_1.mdwn
+++ b/hints/assignment_7_hint_1.mdwn
@@ -5,9 +5,9 @@
* Where they say "reference system," which they use the letter `r` for, that corresponds to what we've been calling "assignments", and have been using the letter `g` for.
-* Where they say `r[x/n]`, that's our `g{x:=n}`, or in OCaml, `fun var -> if var = 'x' then n else g var`.
+* Where they say `r[x/n]`, that's our `g{x:=n}`, which we could represent in OCaml as `fun var -> if var = 'x' then n else g var`. (Earlier we represented assignments as lists of pairs, here we're representing them as functions. Either can work.)
-* Their function `g`, which assigns entities from the domain to pegs, corresponds to our store function, which assigns entities to indexes. To avoid confusion, I'll use `r` for assignments, like they do, and avoid using `g` altogether. Instead I'll use `h` for stores. (We can't use `s` because GS&V use that for something else, which they call "information states.")
+* Their function `g`, which assigns entities from the domain to pegs, corresponds to a store with several indexes. To avoid confusion, I'll use `r` for assignments, like they do, and avoid using `g` altogether. Instead I'll use `h` for stores. (We can't use `s` because GS&V use that for something else, which they call "information states.")
* At several places they talk about some things being *real extensions* of other things. This confused me at first, because they don't ever define a notion of "real extension." (They do define what they mean by "extensions.") Eventually, it emerges that what they mean is what I'd call a *proper extension*: an extension which isn't identical to the original.
--
2.11.0