Jon, (01)
I agree: (02)
> This is all true, well enough, but it always helps me to realize
> that some people I know (logicians, model theorists) use "model"
> to mean anything that satisfies a theory, whether it be a formal
> construct that we make out of sticks and strings or another sort
> of thing in the world, while other people I know (engineers and
> applied mathemticians) use "model" to mean an analogue model or
> the target of a morphismin, in semiotic terms, an icon of the
> object being modeled. These senses of the word are not the
> same but they are perfectly compatible. (03)
In Ch. 1 of my 1984 book, I included a brief discussion of a similar
comment by Carl Adam Petri (of Petri-net fame). Excerpt below. (04)
> Taking all that into account, it still makes sense to say that
> a theory is "true of" the syntactic constructs that the model
> theorist constructs and also "true of" other sorts of things
> in the world. The theory picks out only those properties
> that the object and its icon share, which sharing is
> just what makes the icon an icon of its object. (05)
I agree. (06)
John
____________________________________________________________________ (07)
Excerpt from Ch. 1 of _Conceptual Structures_, by J. F. Sowa: (08)
The word _model_ has multiple meanings in engineering, logic, and common
speech. Petri (1977) noted three different meanings in the phrases
_model of an airplane_, _model of an axiom system_, and _model farm_: (09)
* Simulation. A model airplane is a simplified system that simulates
some significant characteristics of some other system in the real world
or a possible world. (010)
* Realization. A model for a set of axioms is a data structure for
which those axioms are true. Consistent axioms may have many different
models, but inconsistent axioms have no model. (011)
* Prototype. A model farm is an ideal or standard for evaluating
other less perfect farms or for designing new ones. (012)
Petri maintained that a common basis should be found for these three
different ways of modeling. Conceptual graphs, indeed, form models in
all three senses of the term: the graphs simulate significant structures
and events in a possible world; a set of axioms, called laws of the
world, must at all times be true of the graphs; and certain graphs,
called schemata and prototypes, serve as patterns or frames that are
joined to form the models. (013)
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