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 Ahnentafel Questions (I) (Posted on 2004-04-11)
In genealogy, a pedigree chart, which shows one's direct ancestors (parents, grandparents, etc. but not siblings, cousins, etc.) is often replaced by the equivalent but space-saving Ahnentafel table.

An Ahnentafel table is simply a numbered list of each ancestor, usually on separate lines. The "root" person goes on line 1. Then, for any person on line n, his father goes on line 2n and his mother goes on line 2n+1. Every ancestor gets a unique line, and every line gets a unique ancestor* (mathematically, at least -- in real life Ahnentafels, because a person may not know all of his ancestors some lines may be blank, and in the case where cousins married, their common ancestors may show up in several places in their children's Ahnentafels).

Question 1: Your great-great-grandfather(2nd-great-grandfather) was the first of his name (surname) (which you inherited) to come to America. What is his Ahnentafel number? What is the Ahnentafel number of your nth-great-grandfather of the same name?(Assume the the Western tradition where a child inherits his father's surname)

Question 2: Your Mitochondrial DNA is passed on only from your mother, who got it from her mother,etc. What is the Ahnentafel number of the great-grandmother from whom it "originally" came? Of the nth-great-grandmother?

[Hint: for the general case (nth-great-grandfather in question 1, nth-great-grandmother in question 2) it might be easier to work with m=n+2; m is the number of generations between the ancestor and your children. For n=1 (your great-grandfather), m=3 -- three generations in between: your grandfather, your father, and you.]

*This statement (that there is a one-to-one correspondence between Ahnentafel numbers and the set of all natural numbers) is fairly easy to prove. And, in fact, the proof is part of a later puzzle in this series. For this puzzle, it can simply be assumed.

 See The Solution Submitted by TomM Rating: 2.8333 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 re(5): Thanks heaps! | Comment 14 of 15 |
(In reply to re(4): Thanks heaps! by e.g.)

I'm sorry, but the only thing clear to me at this point is that I'm really missing something here.  Please help out an old man who went to college before there was "Computer Science" by giving an example that illustrates the difference between "binary tree" and "Ahnentafel."
 Posted by Richard on 2004-04-14 15:17:53

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