On 2011-05-16 16:09, Peter J. Seymour wrote: > On 2011-05-16 13:03, Richard Smith wrote: >> On May 16, 8:20 am, "Peter J. Seymour"<[email protected]> >> wrote: >> >>> This set me wondering: How large do single trees get? So here is a >>> challenge for you all, What is the largest single-tree gedcom you are >>> aware of, does it consist of sensible data, and more to the point how >>> large is it (File size in bytes and number of individuals, both metrics >>> are needed please? >> >> If you google for 'BUELL001.GED' you'll find a large GEDCOM file by ..... at 150 generations it > breaks an assumed annotation limit in the Gendatam Suite reports. ..... > > Peter This amused me. Toying with providing better resilience in report annotation at high generation numbers, I encountered this unhelpful piece of numerology: Generation 149: G146 Grand Parents List size 16 individuals (out of 356811923176489970264571492362373784095686656 possible) As far as I know the number is correct. I would not be surprised if it is more than the total number of atoms in the universe. Obviously, as you go back through a binary ancestral tree, the span doubles at each generation. At the same time, on travelling back in time the total world population size dimishes. There will come a point at which the span of the tree exceeds the then world population. The "possible" number given above cannot in practice exceed the world population and for various reasons the practical limit will be somewhat smaller. A quick estimate based on a few assumptions puts the crossover date for a tree starting today at not earlier than 1700. Since a complete tree must exist, this means that conflation of ancestry links is not just a possibility, it is a necessity. One can also deduce on a probability basis that while conflation in this hypothetical tree might be unusual for the 1900s, it will be not uncommon for the 1800s and unavoidable for the 1700s. In cultures with a high degree of inter marriage it will obviously be more common than the above physical constraints dictate. Lecture over. I just thought I would share this piece of serendipity. Peter

On 20 May 2011 in soc.genealogy.computing, Peter J. Seymour wrote: > This amused me. Toying with providing better resilience in report > annotation at high generation numbers, I encountered this unhelpful > piece of numerology: > > Generation 149: G146 Grand Parents List size 16 individuals (out > of 356811923176489970264571492362373784095686656 possible) I didn't do the calculation out to check the low digits, but the order of magnitude is correct. > As far as I know the number is correct. I would not be surprised if > it is more than the total number of atoms in the universe. Actually, it's about the square root of the total number of atoms in the universe, which is estimated at about 10^80. (The number above is 3 * 10^44.) http://en.wikipedia.org/wiki/Observable_universe#Matter_content > Obviously, as you go back through a binary ancestral tree, the span > doubles at each generation. At the same time, on travelling back in > time the total world population size dimishes. Brian Pears has written some interesting articles on the subject: http://www.bpears.org.uk/Misc/AncestorParadox/ -- Joe Makowiec http://makowiec.org/ Email: http://makowiec.org/contact/?Joe Usenet Improvement Project: http://twovoyagers.com/improve-usenet.org/