Re: Genealogy For The Beginner

Bob LeChevalier <lojbab@[EMAIL PROTECTED]
> writes:

> Haines Brown <brownh@[EMAIL PROTECTED]
> wrote:
> I find nothing in your summary objectionable.  But you omitted one
> concept I don't fully understand myself in its technical aspects, but
> still use metaphorically when thinking about data and facts.
>
> That concept is the one of "fuzzy" truth values (and thereby fuzzy
> logic).  Very seldom can we assign perfect truth or perfect falsehood
> to an alleged fact, and sometimes we aren't all that sure what
> standard of truth we want to apply to a putative fact.

This gets kinda difficult. Yes, our observations are approximate. I'll
never forget studying standard deviation as a neophyte freshman ;-(. But
this obscures the difference between objective probability (processes
are actually rather random), and subjective probability (we are ignorant
or our measurements are inaccurate). Fuzzy logic is an aspect of set
theory that addresses degrees of truth, not probabilities of fact. The
difference is often taken as being between subjective truth in the
former case, and objective truth in the latter. The latter engages such
things as a probabilistic causality that are quite independent of the
observer. This is often brought up in the context of quantum mechanics,
but it is of general application. Einstein insisted that God does not
play dice, but now we all know better. On the other hand, fuzzy logic
sup****ts partial member****p in a set so that our logical statements
cab accommodate loose categories.

> Hugh has three possible ancestors to his earliest "proven" ancestor.
> He could, by whatever means he chose, assign a fuzzy truth value to
> each of them, thereby entertaining all three possibilities at once.
> If he ever gets further information, the truth values he assigns might
> change.

Yes, there are many examples. We might identify ourselves as
"Americans", as Black, as male, etc. Each represents a truth in a
certain conceptual framework. You might have some weak evidence that
points to descent from a particular person, but you are not entirely
sure. Is this a question of objective truth or of subjective truth where
fuzzy logic would apply? Generally there is really only one father (as
DNA would show), but we are ignorant of just who it is. So maybe fuzzy
logic would be appropriate.

> One of the problems with data display in modern genealogy programs is
> that there is usually no way to communicate fuzzy truth.  In Legacy, I
> can assign a confidence level to a source for a particular datum, but
> unless someone digs down into the innards of my data and looks at that
> confidence level, they'll never see it - it doesn't figure into any of
> the displays or re****ts above the obscure footnote level that in fact
> probably nobody will ever read, including me.  So I never bother
> filling it in.

Very interesting. What you are saying is that a print (printed page or
on a browser) cannot accurately reflect the reality of the lineage with
all its uncertainties. Normally when one prints something, what is
printed is static, unambivalent. Is it possible to print uncertainty? A
conventional way might be to use a dotted line rather than a solid line,
or lines with different colors, although that would be unconventional
and would require the display of a color key to indicate degrees of
uncertainty.

> I envision a tree display that would display the most likely choice,
> but perhaps if you hovered on a particular link, it might display
> multiple trees overlayed, with different colors or densities based on
> relative likelihoods.

That seems easy to do in CSS, but I suspect it is like your footnotes:
people are unaware of the other possibilities until their mouse hovers
over a person, fact or relation. For that matter, such as hover could
easily cause a pop-up that provides the information about the
uncertainty. But I get the impression your aim is to have the
uncertainty immediately obvious rather than depend on the visitor to the
site pursuing more information.

Of course, nearly all display software does not use CSS, and since most
of it is proprietary, there's not much you can do about changing
appearances. All I know is that if one can display a lineage in CSS,
what you suggest can be done. Incidentally, I was once interested in how
to render a descendant re****t entirely in CSS. Here's my little
experiment: www.hartford-hwp.com/genealogy/Brown/brown-1.html . I didn't
try to develop this little rendition experiment because no one seemed
particularly interested.  

> I could imagine that with proper calculation that I don't myself know
> how to do, that immediate ancestors that one is sure of, would show up
> dark and boldly colored, and as one works back up the tree towards
> Adam and Eve, the lower probabilities of the data being factual would
> show up less bold and dimmer.  The lines one has more evidence for
> would be strong, and the lines with weaker evidence or multiple
> possibilities would show up weak (and expand into the multiple options
> being displayed in the appropriate user-interface conditions).

There are surely practical difficulties, but the notion of increasing
transparency or fading (quite different things) are easily handled in
CSS. 

-- 
 
       Haines Brown, KB1GRM