6-man EGTB collecting tip
by Cato the Younger » Thu Jan 05, 2006 4:37 pm
http://sites.google.com/site/chess2u/Nalimov-Endgame-Tablebases/frequency-of-the-diferent-nalimov-egtb-6-men
Collecting the entire set of 6-man EGTB is intimidating and impractical for most people who don't have the necessary 1.2 terabytes of free disk space on their hard drives. But there is a practical if imperfect solution to this problem: only collect the most important--that is to say, the most frequently occurring--combinations.
There are 365 possible 6-man combinations. If you collect just the top 20 of them, by my guess you will have over 56% of the 6-man situations that happen in engine vs. engine games. If you get ambitious and go for the top 50, you will have over 79%. But if you are super-inefficient and collect only the bottom 100 combinations you will have only 0.16% coverage! I mean really, what good is a KNNNNK tablebase to you unless you like horses?
Now there is one issue with this suggestion that I will let others elaborate: the "incomplete tablebases" problem. For example if you have a tablebase with pawns and don't have the one that it converts into following a pawn promotion, you could have some problems. But my general impression is that if you go for maximum coverage in statistical terms that's a better approach that getting all the pawnless combinations first, many of which hardly ever occur. KRRKBB for example happens less than once every 100,000 engine games!
According to my database, here are the top 100 most frequently occurring combinations, ranked in order. You really don't need much more than this, as these cover about 92% of all 6-man combinations that actually happen in engine games. (And for practical purposes you can toss out any 5+1 combinations I show here because if your engine can't solve those without help you need a new engine.)
KRP KRP
KRPP KR
KPP KPP
KRP KPP
KBP KNP
KBP KPP
KRPP KP
KRP KBP
KPPP KP
KQPP KP
KBPP KP
KBP KBP
KRB KRP
KNP KPP
KQP KQP
KQP KPP
KRBP KR
KNP KRP
KQRP KR
KRN KRP
KBPP KB
KNP KNP
KNPP KP
KBPP KR
KQP KRP
KRNP KR
KRPP KB
KQPP KQ
KQRP KP
KBPP KN
KQBP KP
KPPP KR
KNPP KB
KNPP KN
KQR KRP
KNPP KR
KQPPP K
KRPP KN
KRB KRN
KQRPP K
KQP KBP
KRPP KQ
KRPPP K
KQQP KP
KQPP KR
KRR KRP
KRRP KR
KPPP KB
KRBP KP
KQBPP K
KQNP KP
KQP KNP
KPPP KN
KRP KBN
KQQPP K
KQR KPP
KRB KBP
KRB KRB
KRB KPP
KQBP KB
KPPP KQ
KRBP KB
KRNP KP
KRBPP K
KBPPP K
KRN KRN
KRB KNP
KQB KQP
KBNP KR
KQPP KB
KQNPP K
KQRBP K
KQRP KB
KQB KPP
KRBP KQ
KQP KRR
KRN KPP
KBPP KQ
KQBP KN
KRN KBP
KQPP KN
KQBP KR
KRN KNP
KBNP KP
KQP KRB
KQN KQP
KPPPP K
KQRB KR
KRBP KN
KBN KBP
KQNP KB
KNPPP K
KNPP KQ
KQR KBP
KRRP KP
KQBP KQ
KRNPP K
KBNP KB
KQQ KPP
KQR KQP
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.