independence and multiple viewpoints

[cal]

hi, all -


jan kreft wrote
>so the problem is lack of independence. If two versions would be
>independent, output agreement would be sufficient, right?
>
>Of course, true independence can't be achieved, but it is the goal.
>
>And I wouldn't know of anything better than comparing two versions that
>are as independent as possible.

and miles parker wrote:
>Please someone correct or confirm, but isn't the point that two completely
>independent implementations _will_ tend to recreate errors in the same
>places, thus overturning the assumption that multiple versions of a model
>validate the model? This conclusion challenges some assumptions, but makes a
>lot of sense to me.

miles has the gist of my rememberance about profesor leveson's work right
(i've heard her speak about it, but not read the book either) - independence
of modeling effort is not the same as independence of modeling errors

i also agree with jan that multiple different viewpoints can help in
validation of complex systems - we've advocated using multiple models in all
of our modeling applications (i've also shown it to be helpful in some
communication protocol simulation and verification modeling long ago), and
raised it to a principle in our knowledge-based integration infrastructure -
NO one model or modeling method can answer all important questions about a
complex system (which then leads to a requirement for developing techniques to
integrate information across different models and modeling methods)

more later,
cal


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