From: Charles Hixson (charleshixsn@earthlink.net)
Date: Fri Dec 20 2002 - 09:31:44 MST
Rafal Smigrodzki wrote:
>Joao wrote:
>
>
> ...
>
>it is a fact of
>life that certain physical, chemical and information -management engineering
>problems are hard, and ..., their ability to resist DNA damage is also limited.
>...
>Rafal
>
(Sorry for the editing chop job, but...)
Actually, that's a relatively easy problem. It's evolving the solution
that's difficult, not describing it.
Solution: Have a complex of cells that combines multiply-duplicated DNA
strands with extra error checking. Instead of "I tell you twice!"
(Paired nucleotides.), use an "I tell you 4 times!" (or whatever number
is secure enough). This gives you a reference standard. You don't want
to have too many of these cells, as they will be expensive. But they
are your Read-Only library. If you have reason to suspect an error, you
check it against the library. Also you make sure that messages are
signed on the way two and from the library cells, so that both the
sender/recipient and the reference target can be verified. How to
correct the problem is a bit more difficult, but fortunately evolution
has long been working on that. You might also need to give each cell a
URI (how many bits would be needed?)
You will notice that 1) many of these techniques are in use in the
internet, and 2) they are much easier to design than to evolve. I could
easily design a technique for assigning each cell a URI. Evolving it is
quite a different matter. (Stab 1 at a design: Cells only divide in
half, so this is a binary sequence. Pick a maximum number of divisions
to allow. Say 1000. Then you need about 2000 bits. Use base 4
notation c = new, g = left, a = right, t = other. The initial cell
starts as URI ctttt....tttt. When it divides, it divides into
actttt...ttt and gctttt..tttt these divide into aactttt....ttt,
agctttt...tttt, gacttt...tttt, and ggcttt...tttt. Etc. Note the
constant length of URIs. This is an optional choice. You could as
easily use ttt as a stop code, which would allow for an unlimited number
of generations. [Remember: the URIs need to be signed by a validating
third party, so each cell division would require a midwife]).
The fact that this is a simple design problem doesn't make it as simple
thing to evolve. E.g., URIs don't become useful until after utilities
are built that assume their existence.
This archive was generated by hypermail 2.1.5 : Wed Jan 15 2003 - 17:58:49 MST