ONT Re: Qualitative Understanding Of Complex Systems
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QUOCS. Note 3
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JA = Jon Awbrey
MW = Matthew West
I would like to revisit under this heading some of our previous
considerations of systems ideas, so I will copy a few excerpts
from those earlier discussions, just so I don't lose track of
what went before.
For the sake of context, here is a sample of the preamble,
before we launched into the system-theoretic ideas proper:
JA: 1. Could you tell us what a typical application is like
and what your ontology does for you in such a setting?
MW: The idea is to be an integration model, i.e. provide a data model into which
any data about anything can be translated. This to support exchange between
applications and organisations. A specific application is to bring together
the engineering data for an off shore oil rig produced during design and
construction and hand it over to the owner operator to be put into the
many and various (and different) operating systems.
JA: 2. Could you pick out a few terms or concepts that you think
are especially important and tell us how defining them the
way you do is critical to success in practical applications?
MW: Possible_individual is probably the most important concept, and making it
a 4D definition. What is really important is not that anyone can model
what they want how they want, but that everyone can translate their
own information into a single view that is unambiguous, and open
to as few interpretations as possible.
MW: Equally it is important that the model should have a way of saying
anything. It is the inability to state what you mean accurately
that leads to the abuse of data model structures to accomodate
data with an implicit meaning.
JA: 3. Given the variety of different ideas about data models that we've seen,
it might also help if you could say a few words about how you see them.
MW: The structure and meaning of data, is the few words version.
A longer version can be found in:
http://www.matthew-west.org.uk/Documents/princ03.pdf
Here is how the I introduced the systems-theoretic approach:
JA: I have a general interest in intelligent control systems,
but I never found those 3d/4d discussions very helpful.
When I think about these things in systems theory terms,
it always starts with some state space X that contains
all of the logically possible states of the system you
want to think about. Your first stab at dealing with
process will then be in terms of a "path" p : R -> X,
where R is a real line that you think of as the time
domain. Physical laws and practical constraints are
then expressed as subsets of X and subsets of the
set {p : R -> X} of all possible paths through X.
JA: Just as a subset of X corresponds to an indicator function q : X -> B,
where B is the boolean domain -- here, q is the sort of thing that is
convenient to think of as a "proposition about X" -- constraints on
paths p : R -> X can often be expressed through the intermediary
of other functions that one builds up from X, R, and B.
JA: Now, my question is: Can I think of a possible_individual as being
associated with such a path p : R -> X through such a state space X?
JA: Remark. In the beginning, X is really the state space of the whole system.
It can be a tricky question to say whether X decomposes into some form of
composite, but let's start with the easy case, where X = X_1 x ... x X_k,
a cartesian product of component state spaces X_j for j = 1 to k, and X_j
is the state space of the j^th component subsystem. Then let us suppose
that we are talking about one of these ostensibly independent components,
and read what I asked above with X_j in for X.
JA: Rephrasing the question: Can I think of a possible_individual as being
associated with such a path p : R -> X_j through such a state space X_j?
Jon Awbrey
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