[Retros] SPGs enabled by A1.3

[andrew buchanan]

Apologies for sending the previous mail. A literal
slip of the finger while editing. 

[Why mail systems don't have an "are you sure?" button
before sending I don't know. That step is truly
irreversible, while deleting a document (which is
usually easy to reverse anyway) is normally encumbered
by an unnecessary "are you sure?" check.]

In particular, apologies to francois that his email
address appears in the body of the mail.

I am interested in how francois plans to prune the
search for x=6 KK positions. The obvious idea is to
ensure that the 6 non-capturing moves are distributed
3+3 to the two players. (So positions similar to
Francois' second DR SPG could never reach KK.) It may
also be possible to partition the positions so e.g.
3-2 positions are being explored separately from 2-3
positions, with separate consideration for capturing
and non-capturing moves.

DR does ensure that the exactly 7200 legal KK
positions don't interfere with one another. I.e. if
one such position has been achieved (presumably
non-uniquely) in n ply, then this will not spoil the
chance of achieving a neighbouring KK in n+1.

One table that Francois could presumably produce
fairly easily would show for various x & n the number
of SPGs (together with the total number of positions
with that x & n. That would give us a heuristic
estimate of the chance that x=6 will yield the holy
grail for one of these 7200 positions.

As always Francois, thanks for all your work.

Cheers,
Andrew.

PS: What do you plan to do with the other 8 DR SPGs? I
would be very happy to find them a home on my website
at your convenience. In any case a private email to
one person does not constitute publication :-)