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Re: [ontolog-forum] Ontological Means for Systems Engineering

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Ian Bailey" <ian@xxxxxxxxxxxxxxxx>
Date: Fri, 23 Jan 2009 14:43:09 -0000
Message-id: <007d01c97d68$fb2fbb90$f18f32b0$@com>

Hi Matthew,


Then we can add a third class, call it “System” and put that name in a NameType intentionally constructed by Matthew. The point was that the name doesn’t matter as long as we can identify the extent of the class. For example, I might decide to call the class you identified “widget”. Extensionally, it’s the same class, I just give it a different name. Because IDEAS/BORO has a sophisticated(ish) naming pattern, I know that when Canadians say “system” they are referring to a different class to the one you call “system”.


We didn’t have the option to impose a new definition of “system” on any of the parties. They had their own definitions, and a tiny ontology project was going to stop the combined systems engineering departments of some the largest defence agencies in the world from doing things their own way. The same goes inside companies, I should add.  This is why corporate taxonomies are all given a stiff ignoring by the users, and one of the reasons why all those “corporate data model” projects of the 1990s ended up producing something no-one ever used. Either the users don’t agree with the terminology (in which case, they dismiss it off hand), or they see a word they think they recognise and use the model/taxonomy in an unexpected manner.




Ian Bailey



From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Matthew West
Sent: 23 January 2009 13:26
To: ian@xxxxxxxxxxxxxxxx; '[ontolog-forum] '
Subject: Re: [ontolog-forum] Ontological Means for Systems Engineering


Dear Ian,



The big challenge in ontology is to figure out what’s different about a system to any other physical item.

[MW] I agree

Why is a car considered a system, but a rock isn’t, for example.  We had a lot of debates around this in IDEAS meetings. You can easily ascertain the extents of aircraft, armoured vehicles, etc., but the extent of the classes each nation were calling system differed. The UK framework (MODAF) saw a system as any kind of man-made object that had functionality (i.e. cars=yes, rocks and humans = no). The Canadians were very specific that a physical object only became a system when it was manned, maintained and ready to function – a narrower set than the UK one. The US (DoDAF) description was similar to the UK but also included humans/animals. So, we had three overlapping classes, each of which was called “system” by different parties. By extensional analysis, we worked out that what MODAF calls “CapabilityConfiguration” was an exact match for the Canadian “System”.


[MW] Well I don’t think any of those are wrong, but perhaps a little restrictive. The two things that characterise a system for me are:


1.       It has a function/capability/purpose.

2.       Has parts that can be replaced by functionally equivalent parts.




Matthew West                           

Information  Junction

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