Re: Nested Sets And Pedigrees

"Paul Tiseo" <123tiseo.paul_at_123mayo.edu (drop the numbers)> wrote in message news:MPG.1717b6621ca5cac39896d8_at_news.easynews.com...
> In article <c0d87ec0.0204051000.79ec9d8b_at_posting.google.com>, 71062.1056
> _at_compuserve.com says...
> > >> Make two trees:
> > - a mother-tree where X is a child of Y if Y is the mother of X,
> > and
> > - a father-tree where X is a child of Y if Y is the father of X. <<
> >
> > I am not sure that would work. Consider a family of several
> > generations with both sons and daughter. Fred is the father of
> > (Sally, Tom); Fran is the mother of (Sally, Tom). When Sally gets
> > married and has a grand-daughter, which tree is her child put into?

Every child is added to both trees, the mother-tree because it has a mother, and the father-tree because it has a father.

> There are many potential complications
> that prevent you from making clean tree-like representations. Primarily,
> looping can arise due to consanguineous mating (inbreeding).

There is only a problem with the father/mother-tree proposal if people change sex, but even that can be solved by extending the identifier of the person with a gender attribute.

• Jan Hidders