Re: A simple situation shows confusion about basic concepts

From: Konstantinos <>
Date: Wed, 27 Oct 2004 02:25:42 -0400
Message-ID: <>

> Thank you for your replies, fellows. It seems I may have got you confused
> with the attribute 'relation_type' in the KB entity. That has nothing to
> do with relationships between tables in the database model. Its purpose is
> to specify the type of *conceptual* relationship the two UCs of a KB entry
> have, e.g. the concepts of "car" and "vehicle" have a "is a"
> relation_type. From his comment above, it seems Laconic2 understood it,
> while I am not so sure Kostas did.

I think everybody understood that crystal clear. :-) You have what Alan says, a rectangle for the UC relation and the diamond that relates UC to itself, which as I said is a reflexive association.

Since you have different kinds of relation types (yes the relations between UCs, nothing to do with the relations or tables of the database), Laconic2 is also right in that all 3 attributes uc1_id, uc2_id and relation_type are the primary key. If you do decide to use autonumbers, I would suggest you use them on the UC table, not the KB table. I find this to be useless and redundant.

I am not sure, however, if this a flexible design for a knowledge-base but neither can I suggest an alternative as this is not my domain. If you are into knowledge bases and ontologies, take a look at Protege. It is free software from Stanford university.

Konstantinos Received on Wed Oct 27 2004 - 08:25:42 CEST

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