Re: Inequivalence of models

[John M <***>]

Tim,
sorry, I sent my reply to Steve before I received this - your one.
I did not take the engineering view (in wording), but I think the meanings
are not far away.

One remark on your last lines here:
I feel 'inequivalent' models are aspectually different, commensurability may
be one characteristic within such. An inequivalent (by meaning!) model pair
does not have to be impredicative (though it can be). The "state-based"
model-pair (1st time I read this name) is IMO aspect-based limited as well
(if I understand its meaning right).
I deem (as you know) the engineering thinking sort of reductionistic.

Otherwise have a good Sunday

John M
----- Original Message -----
From: "Tim Gwinn" <***>
To: <***>
Sent: Sunday, January 16, 2005 11:07 AM
Subject: Re: Inequivalence of models


> Steve,
>
> SJ:
> > So here are my questions:
> >
> > 1) Are these two models of the car(mechanical and
> > electric) really one model? Why or why not? What is
> > the criteria that allow us to say that they are two
> > different models.
> >
> > 2) If they are different models, what is the largest
> > model that subsumes them? How would one go about
> > constructing it?
>
> TG:
> 1) I would say they are two separate models: each formal representation
> maintains synonymies with very different aspects of the car.
>
> 2) I don't think it would be hard to overlay an electrical diagram onto a
> mechanical diagram. (This obviously has to happen at some point during the
> engineering, so that mechanically, they know where the battery will fit,
> each wiring harness will pass, the bulbs will be located, etc.) The main
> point, I think, is that the abstract symbols for bulbs, battery, wiring
> connections, etc. can map onto the mechanical diagram, (or that both can
map
> onto a third diagram) -- there is a commensurability.  With inequivalent
> models, there would be a lack of commensurability: there would be no way
to
> map from one to the other. So, for example, impredicative relational
models
> are incommensurable with state-based models.
>
> Regards,
> Tim
>
> P.S. - Go New England Patriots!! (Reference to the NFL playoff game today
> for those of you that don't follow American football.)