Author: guy haworth
Date: 16:57:18 09/18/99
Go up one level in this thread
Eugene,
I'm v impressed by your 'Monday' prediction; what are the main parameters of yr
computing engine - must have loads of RAM, Hz and disc-drives.
Lewis Stiller sent me some stats which I lined up with his thesis results
successfully: I hope they might encourage and/or help you.
Assume White = 1st player, Black = 2nd player
1,546,346,340 distinct KQQKQQ positions
(Ks apart but 'unreachables' possible ...
eg double-check, both sides checked)
44 = max-depth wtm win ... and maxdepth position demonstrates
not all Q-checks lead to a win and
very easy for Black to turn a deep win into shallow win
1,280,546,724 (= 82.81%) distinct wtm wins but lots in 1m or 2m
1,186,868,923 white wins in 1m (mate or bQ en prise)
38,200,845 white wins in 2m (mate or wQ..bK..bK skewer)
1,271,619,037 (= 99.3% of all wins) Wh wins in 6m or less
What depth in ply can Fritz-on-a-PC reasonably search full-width to in KQQKQQ?
I would expect it to be less than 16-ply which I have seen quoted in other
searches. The EG-db of course adds value where depths/distances beyond the
search-tree horizon are involved.
[ If you need any more stats, plse request via this board. Got a glitch in
email at the moment. ]
Turning to non-KQQKQQ dbs, there is more dialogue on the GK-v-WT bulletin board
about using heuristics in a KQP(g7)KQP(d6-3) EG-db attempt ... or making
assumptions like 'the black pawns don't move'.
The simplifying assumptions/approximations are I think:
P=Q only (so forget P=R,B,N ... if GK wins with P=N, I'll hold my hand up)
P does not take Q ... as this will reduce to an evaluated 5/4-man ending
If White has one more Q than Black for more than 1 ply, White wins.
If GK is to win, then at the end, for some moves, Black's pawn(s) will not have
moved ... and Black could choose at some stage NOT to move them. If the Black
Ps are doing more for White than Black, White will not capture them either.
The following suggestion, which I've seen elsewhere, therefore seems
interesting:
"Generate the '5-man' database KQPKQ with the constraints of the Black pawns on
'bx' and/or 'dy'". This would be a new mode of EG-db generation; how this gets
implemented in retrograde analysis is not clear to me. The above three
approximations/simplifications would still apply.
I've been offline for a while but it appears the GK-v-WT BBS has 'bottomed out'
endgame G (which has an h rather than a g pawn) and discovered that it wins for
GK. So, it looks like we are still heading for endgame-D with a g5-7 wP and
KQQKQQ as a possible outcome of that.
See (eg) http://www.gmchess.spb.ru/kasparov-world.html where they call endgame-D
position "A".
Rgds, Guy
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