Re: Storing data and code in a Db with LISP-like interface

From: Bob Badour <>
Date: Fri, 21 Apr 2006 18:33:19 GMT
Message-ID: <Pz92g.63780$>

JOG wrote:

> Bob Badour wrote:

>>JOG wrote:
>>>Bob Badour wrote:
>>>>Alvin Ryder wrote:
>>>>>I agree linked-lists aren't as powerful as the RM but LISP and Prolog
>>>>>are not merely about lists.
>>>>>Both Prolog and LISP can represent information and indeed knowledge
>>>>>well beyond the RM, that's why they are popular with the ai community!
>>>>Given the standard definitions of information and knowledge, that's a
>>>>rather astounding claim. Do you have anything that might back it up?
>>>Prolog models a greater subset of predicate logic than relational
>>>theory due to its inclusion of negation and disjunction. As such it has
>>>been traditional popular in classic-AI as the basis of inference
>>>engines. Whether this allows it to offer a better representation of
>>>'knowledge' is up for debate.
>> [snip]
>>Are you suggesting that NOT is not negation or that OR is not

> Of course not. I am sure this is a rhetorical question but I cannot
> ascertain its point - I think you are referring to relational algebra,
> but this is not the same as the use of negation in explicit
> declarations such as P(x) || Q(y) (for instance). In RM the user has
> to remember this predicate. In Prolog, the program memorises it for
> you, for good or for bad. To compare the two is hence comparing apples
> and oranges.

The point is the relational model basically supports both with the one small requirement that one must specify one's universe. I do not understand what you mean by 'has to remember this predicate'.

>>I am curious what basis you think you have for the
>>astounding statement: "Prolog models a greater subset of predicate logic
>>than relational theory due to its inclusion of negation and disjunction."

> I am regurgitating from memory - I think it _may_ have been Codd
> speaking of the active decision on his part to use the subset of
> predicate logic that he did, but I will have to dig it out in the piles
> of papers I have.

Somehow, I doubt Prolog returns many infinite sets.

> Either way, prolog is a dwindling language anyhow:
> (

I don't see where you established it is dwindling. Other than the fact it might be included in the first 50 languages, I doubt it ever occupied a spot in the top 50. Received on Fri Apr 21 2006 - 20:33:19 CEST

Original text of this message