Re: Stored fields ordered left to right

From: Dawn M. Wolthuis <dwolt_at_tincat-group.com>
Date: Wed, 14 Jan 2004 18:14:12 -0600
Message-ID: <bu4m0m$pgh$1@news.netins.net>

"Adrian Kubala" <adrian_at_sixfingeredman.net> wrote in message news:slrnc0bkk8.8lg.adrian_at_sixfingeredman.net...
> Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> > "Adrian Kubala" <adrian_at_sixfingeredman.net> wrote:
> >> Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> >> > Hope has a cat named Geneva and a dog named Rugby.
> >> > Shanna has no pets, but did have a dog named Monte who died in 2002.
> >> >
> >> > Given only these statements, I might immediately come up with
> >> > something like this:
> >> > [...]
> >> > PEOPLE("12345") = { "Hope", { ("cat", "Geneva", NULL) , ("dog",
> >> > "Rugby", NULL)} }
> >> > PEOPLE("12346") = ( "Shanna", { ("dog", "Monte", "2002") } }
> >>
> >> This is not modeling, because all you've done is associate some lists
> >> with each person, without any formal way to reason about what the lists
> >> MEAN. I could just as well "model" the first proposition as:
> >
> > Are you saying it is not modeling because I did not show the logical
> > steps I took to arrive at this or is it that modeling with a function
> > is necessarily not a model or what?

>

> You are not modeling with functions, you are modeling with lists. I can
> tell because there was no mention of lists in the original preposition,
> and lists are not required to describe functions, but nevertheless lists
> have snuck into your model. On the other hand, the above would be a
> perfectly good function-based model of "Person 12345 has the list (hope,
> (cat, geneva, null), (dog, rugby, null))".

My function is named PERSON and it maps the string "12345" to a set of strings or string tuples. I can use more precision in the future to ensure that you can see that this function provides a model for a plausible implementation.

>

> I say it's not modeling because I don't believe you have a general
> theory for how prepositions (in this case) can be mapped to and from
> lists in a general way, with a useful algebra on lists which preserves
> the truth values of prepositions. It is not enough to provide a post-hoc
> rationalization for why you chose these particular lists for these
> particular examples. But if you do have such a theory I am excited to
> hear it.

That is one of the things I have been working on, starting with studying how the many developers who have worked with this model since 1965 have "post-hoc" been doing this and pulling out common, repeatable processes that are used. Although there is no written document on how to do this (to my knowledge) there also was no such specification for "secretaries" who set up filing systems in days before computers -- and yet the job gets done and the solutions seem to be quite flexible in meeting the needs of a company often for many years (many instances of > 20 years of such databases). It does seem that experience makes a difference in how well the developer (or secretary) has been able to set up such solutions. I'm trying to capture the knowledge of expert developers who use the Nelsson-Pick model as I expect such information will also help with the development of XML documents (which use a model that is very similar).

--dawn Received on Wed Jan 14 2004 - 18:14:12 CST