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

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ron Wheeler <rwheeler@xxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 23 Jan 2009 14:04:54 -0500
Message-id: <497A14D6.2020702@xxxxxxxxxxxxxxxxxxxxx>
I hope that you will find a place on the wiki for this description and a 
summary of the discussion.    (01)

Ron    (02)

Ed Barkmeyer wrote:
> I strongly suggest that we stay carefully on the topic that Andreas 
> raised.  'Systems engineeering', as an engineering discipline, is about 
> _artificial_ things.  So its definition of 'system' is constrained to 
> such things.  While there are certainly "systems" in nature (the 
> argument for 'intelligent design'), we don't engineer them, although we 
> may analyze them to provide engineering insights. If we waltz off into 
> the philosophical question of what a 'system' may be, we have lost sight 
> of the objective.
> Matthew West wrote:
>> 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.
> A project in which I was engaged about 7 years ago, an outgrowth of 
> which was support for ISO 10303-233 and SysML, defined 'system' as:
>    a complex of software, hardware, and human resources that jointly 
> accomplishes one or more business functions. A system may be 
> pre-designed or arise ad hoc by action of one or more of the 
> participating human or software resources.
> And I should be careful to say that the intent of the definition is that 
> a system is a complex of any combination of software, machines, and 
> humans.  There is no requirement for a system to have all three types of 
> elements.
> This is a slight generalization of Matt's characterization, in that it 
> recognizes the existence of parts with subfunctions, without requiring 
> substitutability.
> And this leads to a concept that is critical to systems engineering, but 
> is only assumed in the above characterizations: subfunction.  Borrowing 
> from INCOSE, the NIST paper defines:
>    System design =
> (1) a specification of the structure of the system, ...
> (2) a breakdown of system functions into subfunctions assigned to 
> nominal component subsystems, coupled with a specification for the 
> information and materials that must be available at the component 
> interfaces in order for the subfunctions to be accomplished.
> Systems engineering is about WHAT components do, HOW that is part of the 
> intended system function, and HOW they relate to each other.  It is also 
> about capturing constraints on the system and how those constraints are 
> allocated to (or interpreted for) the components.  It is the 
> 'encapsulation' of HOW the components do WHAT they do, within the given 
> constraints, that creates substitutability.
> The other idea that is commonly associated with a 'system' (from the 
> 'systems engineering' point of view) is heterogeneity, either in the 
> nature of the parts, or in the collection of views (specifications of 
> structure) that are required to understand the implementation of the 
> functions.  (One can leave the design of a purely mechanical system to 
> mechanical engineers, or a purely electrical system to electrical 
> engineers.  It is only when there is a mix of human parts, software 
> parts, major electronic/electrical components, and major mechanical 
> components that it becomes a 'systems engineering' project.)
> Back to Andreas' original point, I have never seen an ontology for 
> systems engineering concepts.  It was the original goal of INCOSE (about 
> 10 years ago) to organize the knowledge of experienced systems engineers 
> into a real engineering discipline, one that could be taught.  What Matt 
> and Ian describe is an activity that was ongoing early in that effort, 
> and I personally don't know whether INCOSE (as a body) believes it has 
> achieved its goal.  Ontology development is about engineering existing 
> knowledge -- it presumes that the knowledge to be engineered is 
> agreed-on by the community it intends to serve.  In systems engineering, 
> are we there yet?
> -Ed
>       (03)

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