Re: Relational/hierarchical data problem

Thanks to all who have replied.

Bob - I found what you said very interesting. The number of animals in this case (goats, incidentally) is likely to be large. There are 41 goats in the current herd and this equates to 208 animal records at present. The herd will stabilise at about 120 animals and will have a high turnover (they are meat goats). We are legally obliged to track the past 5 generations for any given animal, so in a fairly short time we will be dealing with thousands of animal records.

> It might be possible
> to
> > pre-compute the transitive closure in another table then use that to
> > evaluate the shared ancestors.

I'd agree with that - it seems the best way to retain as much performance as possible.

According to what my understanding, collateral consanguinity can be determined by two methods:

1. Canon/common law method - The degree of the more remote of the two subjects from their nearest common ancestor. E.g. Entity 1, Entity 2, Common Ancestor, Consang

   ---

   sibling, sibling, parent, 1 child, parent, parent, 1 child, grandparent, grandparent, 2 nephew, uncle, grandparent, 2 first cousin, first cousin, grandparent, 2
2. Civil law method - Add the degree of both entities from the nearest common ancestor. E.g. Entity 1, Entity 2, Common Ancestor, Consang

   ---

   sibling, sibling, parent, (1 + 1) = 2 child, parent, parent, (1 + 0) = 1 child, grandparent, grandparent, (2 + 0) = 2 nephew, uncle, grandparent, (2 + 1) = 3 first cousin, first cousin, grandparent, (2 + 2) = 4

Evidently method 2 is a better one to use because there is less amibiguity.

Bearing the above in mind, I have a question about the consanguinity values you stated:

> > If parents are half-siblings, one of the grandparents would have
> Consang=2.

Taking one of the half-siblings as the subject, wouldn't the following be true?
- parent -> any grandparent would be Consang=1 - children of either parent -> any grandparent would be Consang=2? I don't see why one grandparent would have a different degree of consanguinity to any of the others from the perspective of either their children or their children's children. How this is affected by the fact that the parents are half-siblings?

Thanks for your help so far!

Regards

Will Received on Thu Feb 20 2003 - 12:53:46 CET