Re: Date for Last Common Ancestor?

Stephen Barnard (
Mon, 12 Aug 1996 04:06:35 -0800

Stephen Barnard wrote:

> Let S_1 be the set of all people whom are alive today. Let S_2 be the
> set of mothers of the members of S_1. In general, let S_k be the set
> of mothers of S_k-1. The size of these sets is nondecreasing (S_k <=
> S_k-1), because everyone has only one mother, but some mothers have
> more than one child.

Oops. I meant to say that the size of the sets in *nonincreasing*, or
better yet, they never get any bigger (and they are most likely to get

Steve Barnard