"Neo" <neo55592@[EMAIL PROTECTED]
> wrote in message
news:1145298018.123938.13480@[EMAIL PROTECTED]
>> ... calling one of us an idiot. Not sure who. :-)
>
> Well if you don't want the compliment, I'll take it :)
LOL
>
>> Prolog is not an inherently type-safe language ...
>
> This is slightly off-topic, but I am curious about your view:
These are good questions, but I'm not sure if you are asking me about my
views on relational data management or on logical rules management. The
difference is simple. Relational describes relation****ps like 'is a' and
'has a' and 'is defined by' while logical rules management simply states
'the relation****p is what you define it to be'.
It has been well over a decade since I wrote Prolog code, so if someone
reading this newsgroup knows Prolog and they see this, my sincere
apologies.
The concept is what I'm trying to convey.
I will answer your questions with statements that are (or resemble)
Prolog.
>
> 1) What is the proper name of the relation****p between person and John,
> person and Mary, fruit and apple, fruit and banana, etc. Ie, fill the
> verb in: person ____ john.
named_instance(john,person).
named_instance(mary,person).
subtype(apple,fruit).
subtype(banana,fruit).
>
> 2) What is the proper name of the reverse relation****p between John and
> person, Mary and person, apple and fruit, banana and fruit, etc. Ie,
> fill the verb in: john ___ person.
? named_instance(john, A )
(to which the system responds)
A = person
(I skipped your question. The answer to the logic of your question is: I
would consider john to be a named instance of the noun 'person').
>
> 3) Just as John and Mary "are" persons, and apple and banana "are"
> fruits, what are person and fruit?
person is a noun. fruit is a noun. In Prolog, they are atoms. They have
no 'meaning' except as defined by their relation****p with john and banana.
(You will notice that I use lower case, even for proper names. In Prolog,
lower case tokens are 'atoms' while a token that begins with a capital
letter is a variable).
>
> 4) Supposing the answer to question 3 is xyz, what is the proper name
> of the relation****p between xyz and person, xyz and fruit, etc?
not a sensible question in Prolog context. There is no notion of subtype
or
supertype. Only expression. Imagine that we are talking about Boolean
logic. A or B. Is A a variable? If we say "A is a B and B is a C,
therefore A is a C," we have defined the transitive property of 'is a'.
Before making the statement, the verb 'is a' had no such property. The
scope of this property may be quite limited. Prolog assumes this. Most
data management languages have a great many meta-rules. Prolog does too,
but they are not based on the data. They are, instead, based on the
logic.
>
> 5) Supposing the answer to question 3 is xyz, what is the proper name
> of the reverse relation****p between person and xyz, fruit and xyz, etc?
>
See above.
Let's say, in Prolog, you want to express the transitive nature of
'contains'. It could look like this:
contains(A, B) :- contains(A, X), contains(X, B).
Now let's establish some facts.
contains(cup, coin).
contains(bucket, cup).
contains(box, bucket).
contains(truck, box).
contains(****p, truck).
We are saying that the coin is in the cup is in the bucket is in the box
is
in the truck is in the ****p.
Now, ask the question: is the coin in the truck?
? contains(truck, coin)
to which the system responds:
yes.
(or 'true.' Not sure anymore ;-).
It does it by comparing the predicate contains/2 to each of the rules in
the
system. There are six matching rules. One is an expression. The rest
are
facts. The comparison doesn't match one of the facts, so the expression
is
invoked. The expression says: any item is inside another item if you can
find an intermediary where the item is in the intermediary and the
intermediary is in the other item... RECURSIVE. Using a depth-first
search,
the system quickly finds that the coin is in a cup where a cup is in a
bucket where a bucket is in a box where a box is in a truck, therefore the
coin is in the truck.
The entire program is in this post. There is nothing else.
HTH,
--
--- Nick Malik [Microsoft]
MCSD, CFPS, Certified Scrummaster
http://blogs.msdn.com/nickmalik
Disclaimer: Opinions expressed in this forum are my own, and not
representative of my employer.
I do not answer questions on behalf of my employer. I'm just a
programmer helping programmers.
--
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