Re: deductive databases

From: alex goldman <hello_at_spamm.er>
Date: Sat, 14 May 2005 08:14:32 -0700
Message-Id: <7089933.45HMLJbSju@yahoo.com>

Robert Low wrote:

> alex goldman wrote:

>> Robert Low wrote:
>>>But what is car(cons(X,Y),X)?
>> It's a relation (whereas in Lips, it would be a function)

>
> So it's just the statement that car of cons(X,Y) is X?

If the inference procedure "knew" about equality, we could write

car(cons(X, Y)) = X, or equivalently X = car(cons(X, Y))

In Prolog, it doesn't, so /one/ way to express "car" relation is like I did.

> (To put it another way, the pair (Z,X) satisfies car(Z,X)
> iff X is car(Z)?)

Er, no "iff", and we only defined car of arity 2. Received on Sat May 14 2005 - 10:14:32 CDT