Subject: HW #3
From: "William J. Rapaport" <rapaport@buffalo.edu>
Date: Sat, 19 Sep 2009 11:25:25 -0400 (EDT)

A student writes:
"For question number 4 on homework #3, which refers to question 32 in
the book, I looked at the next problem number 33, and found it a lot
easier to do the problem instead of the way you referred to in your
example, and I wanted to make sure it was acceptable. So your problem I
would do:

"Some dog is a pet."

Let x be the domain of dogs.
Pet(x) = "x is a pet."

Ex[Pet(x)]

-Ex[Pet(x)]
Ax-[Pet(x)]

Not all dogs are pets.

If some of the quantifiers don't work its because I copied and pasted
from your emails, but like I said I was wondering if this format was
acceptable where basically we can choose the domain. Thanks!"

Reply:  I have 2 replies:

1. Although the book's method is not what I intended, as long as the
   book allows it for problem 33, I'll allow it for problem 32.

2. However, your English translation of "Ax[Pet(x)]" is not correct :-)