On Wed, Jul 25, 2012 at 6:25 AM, John F Sowa
<sowa@xxxxxxxxxxx> wrote:
...
JFS
>> "(that p)" is a kind of quasi-quotation that allows
>> variables in p to be bound to quantifiers outside of p.
PH
> Hmm, I don't think it is correct to think of it as quasi-quotation.
> Rather than quoting the sentence, it treats it as defining a
> zero-ary predicate, and creates a term denoting that entity.
The backquote in LISP can be applied to any _expression_. The IKL
'that' operator can be implemented in LISP by applying backquote
to sentences in some version of logic.
That is probably right. And certainly the "that" operator is syntactically analogous to backquote in that it is a term forming operator that permits quantifying in, which is of course perhaps the most significant difference between LISP quote and backquote. But Pat is (as always) right about the great semantic differences between the "that" and quasi-quotation.
-chris