Saturday, February 1, 2014

Balanced endgames

Is the position balanced ?
Almost all evaluation terms have a endgame component, some evaluation terms only exist for the endgame. In order to tune them it is very helpful not to start games from the starting position. 

A lot of games might be decided without even reaching the endgame, so the outcome of the game does tell very little whether the evaluation values of the winner were good or bad. So it is better to start games from a late midgame position. But here starts the challenge. 

What are good starting positions ?

If the position is to drawish and always leads to a draw it does not help. If it favors one side to much it is also rather useless. To find good starting positions is rather tricky.

I searched the web and some helpful fellows posted positions that they thought were balanced. They searched them with an engine and if the score was within a range around 0 they used it. 

I used those as a starting point and ran a 16000 games tournament between Stockfish and Komodo using 248 of those positions. I then analyzed the resulting games file and got mixed results. Some of those "balanced" were not balanced at all, some of those positions were dead drawn. I then assigned points for usefulness to them. Those below are the ones from the tested 248 positions which seem the most useful. 

Maybe they are of some help to others. The numbers to the right mark the number of games played with this position, the wins by white and black and the number of draws.

PS.: The above posted position is not balanced. White scores about 80% (41 - 2 - 23).

  
  #  FEN                                                     Gm   W    B    D
---+--------------------------------------------------------+-----------------   
  1. 5rk1/N4p1p/1p6/2p2p2/4p3/P4bP1/1PP2P1P/2K1R3 b - -      64   21 - 27 - 16
  2. 5k2/p1p2pp1/2p4p/2N5/1P2R2P/P1P5/5PPK/3r1b2 b - -       64   24 - 19 - 21
  3. 1B4k1/p3r1p1/1n3p1p/4p3/1Rp5/P1P2P2/2P2P1P/5K2 w - -    64   16 - 25 - 23
  4. 2k1r3/2p4p/pp6/2p1p3/b3P2B/P1R2P2/P5PP/6K1 w - -        66   23 - 14 - 29
  5. r4b2/1R6/4k1pp/2ppp3/Pp6/1P3P1P/1BP1K1P1/8 b - -        66   21 - 14 - 31
  6. 2kr4/1p2R1p1/2p4p/Pp6/3b1P1P/6P1/2P3K1/4B3 w - -        64   16 - 16 - 32
  7. 3k4/p1p2p1R/1p2p1p1/3bn3/8/PP4P1/2P3P1/2K2B2 b - -      64   22 - 13 - 29
  8. 3r1b2/5k2/pp3p2/4pp1p/P7/2P2PP1/1PKN3P/4R3 b - -        66   28 - 11 - 27
  9. r2k4/p1p2pN1/1p5p/2p1P1bP/8/1P4P1/PBP2P2/6K1 w - -      64   31 - 11 - 22
 10. 5r2/p3k2p/3pn3/3B1p2/PPPp4/6PP/2P4K/B7 w - -            66   15 - 15 - 36
 11. 3B1b2/p2n1p2/5P2/1k6/1p6/6P1/1p3P1P/1R4K1 b - -         64   10 - 33 - 21
 12. 5nk1/pp3ppp/4p1b1/3pP3/P2P4/3B4/1P3PPP/2B3K1 w - -      64   17 - 13 - 34
 13. 4b1k1/2p1r1p1/1p1p3p/p2P3P/3PP1P1/5K2/P2N4/6R1 b - -    64   15 - 13 - 36
 14. 2k5/2p2p2/p1p2rp1/3n3p/1P2KB1P/P5P1/1P3P2/3R4 w - -     64   17 - 12 - 35
 15. 2k2b1r/3n4/5P2/8/1pp5/4B1P1/1P3P1P/5RK1 w - -           64    9 - 31 - 24
 16. 3r2k1/p4ppp/1p2pn2/8/P2N4/2P3P1/1P3PP1/4R1K1 b - -      64   16 - 12 - 36
 17. 1B4k1/1p4pp/p3pb2/5p2/3P1P2/4PP2/P3K2P/1n1N4 w - -      64   18 - 11 - 35
 18. r7/pp3pkp/1n1p2p1/3P4/5PN1/1P6/P5PP/4R1K1 w - -         64   15 - 12 - 37
 19. r7/5p2/2p2k1p/ppNp1b2/3R4/1PP2P2/1P4PP/4K3 w - -        66   19 - 10 - 37
 20. 4kr2/1pp3pp/p1p5/4b3/4P3/3PB3/PP3P1P/R5K1 w - -         66   16 - 11 - 39
 21. 2r3k1/3b1pp1/4p3/1p2P1p1/1N6/P1R5/1PP4P/2K5 w - -       64   12 - 14 - 38
 22. r3k1B1/1p1b4/p6p/5p2/3p1p2/5P1P/PPP2P2/2K4R b q -       64   23 -  9 - 32
 23. 2n2k2/n4pp1/pp2p2p/3pP3/1P1P2PP/P2KB3/5P2/4N3 w - -     64   18 - 10 - 36
 24. 2r3k1/3b4/p2p2pp/3P1p2/1PpN4/P3P2P/5KP1/2R5 w - -       64   18 - 10 - 36
 25. r7/p4pk1/1p6/4n1p1/4PpP1/P7/1P2B1PP/3K3R b - -          64   13 - 12 - 39
 26. 3kb3/pp2p2p/3p2p1/4n1P1/4PK1P/1PP5/P1N1B3/8 b - -       64   13 - 12 - 39
 27. 2nr1k2/p4p2/4pp1p/2p5/2P3P1/P3P3/2K1BP1P/1R6 w - -      66   25 -  8 - 33
 28. 3k3r/1p2b2p/p3pp2/2p5/P4P2/2NKP3/1P4PP/7R b - -         66   10 - 16 - 40
 29. 2rk4/p4ppp/1pn5/2p5/4B3/P1P3P1/4PP1P/1R4K1 w - -        64   25 -  8 - 31
 30. 3b4/3k2p1/3p4/pp3p2/4bP2/4N1PP/P3K3/3R4 b - -           64   24 -  8 - 32
 31. r5k1/p7/2p3p1/4R2p/7P/2P2P1N/PP4n1/3K4 b - -            64   13 - 11 - 40
 32. 1r4k1/4b2p/2np4/8/1p2R3/1P1R4/P5PP/1K6 b - -            64   15 - 10 - 39
 33. 8/2pk3p/1p4p1/p5P1/2bPnB1P/P7/6K1/1R6 b - -             64   15 - 10 - 39
 34. 3r2k1/pp2p2p/4pnp1/4R3/8/7P/PPP2PP1/3N2K1 w - -         64   21 -  8 - 35
 35. 2r5/4k1p1/p3p1P1/6b1/2p5/7B/PPP5/1K1R4 w - -            64   21 -  8 - 35
 36. 3r1k2/3b1pp1/7p/1p1PpP2/2p1P3/7P/1PB3P1/R5K1 b - -      64   12 - 11 - 41