Author: Helcio Alexandre Pacheco
Date: 08:44:06 09/17/99
Go up one level in this thread
I've studied this chess theme carefully enough to get a master view of it (IMHO
:).
There are many factors that you should consider in your evaluation of the
position.
First of all: I put pawn majorities in 3 class: good ones, bad(or weak) ones and
unclear ones.
An example:
a) White Pawns on: a3,b4,c4,f4,g3,h2 Black pawns: a7,b6,e6,f7,g6,h7
In this case, White has the good and black has the bad one.
b) White Pawns on: a2,b2,c2,f3,g2,h2 Black pawns: a6,b5,e5,f5,g6,h7
In this one, White has the bad one and black the good one.
c) White Pawns on: a2,b2,c2,f2,g2,h2 Black Pawns: a7,b7,e7,f7,g7,h7
In this position, it's unclear if the majorities are good or bad.
One important thing here is that the side with the good one have a great control
of space and the center and therefore will have the better king in the endgame
(in the first position white can put his king on d4 easily... in the second,
black can put his on d5...).
From what I read, It seems that your code already do this classification.
Then we have to consider the other pieces in game. As you said, the advantage of
a majority is bigger in the endgame. But, in which endgames will it be good
enough to give an decisive advantage? Depending on the pieces, a bad majority
can become a good one!
Studing some master games I was able to identify some favorable endings where
the advantage of a pawn majority is (nearly) enough to win. For example:
1) Rook endings: The advantage is not so decisive. There are many rook endings
where one side is a pawn down and can still draw. So you see the position more
or less as a pawn down endgame where the side with the bad majority has good
chances of holding. The side with the good majority can keep good winning
chances if he have the active rook and can cut enemy king.
2) Double Rook endings: In this kind of endgame, other themes are usually more
important as the control of the 7th, active vs passive rooks. But again, good
drawing chances.
3) Queen endings: The side with the majority that is far from its own king has
very good winning chances if his king is safe from perpetual. In this case, the
classification that I made is useless because the bad can turn into the good one
because it's far from the king. Take second example: with queens on board white
can play c3-b3-c4 and create a passer that will be suported by the queen.
4) Minor Pieces endings: These are the endings where the advantage is usually
enough, but with some exceptions: oposite bishops (as always), Knight vs Good
Bishop (the side with the bad structure holding the good bishop). If the side
with the good majority also has bishop pairs he will be winning as the bishop
pair will suport their advance.
When I have a good pawn majority I usually try to avoid the 1st 3 types of
endings because it's more difficult to use the advantage (unless I see I'm going
to get a really winning position). So, in the case of the pawn structures that I
gave, I use the only open file to trade down heavy pieces.
I also don't go for the endgame if it's unclear that my majority is the best
one. I make the position clear before I go for it.
I have 2 interesting games I played against IM's on ICC that ilustrate this
topic:
[Event "ICC 3 0"]
[Site "Internet Chess Club"]
[Date "1999.08.22"]
[Round "-"]
[White "Gruen"]
[Black "Helcio"]
[Result "0-1"]
[WhiteElo "2477"]
[BlackElo "2311"]
[Opening "Scandinavian: Pytel-Wade variation"]
[ECO "B01"]
[NIC "SD.02"]
[Time "07:31:01"]
[TimeControl "180+0"]
1. e4 d5 2. exd5 Qxd5 3. Nc3 Qd6 4. d4 Nf6 5. Nf3 a6 6. Bc4 b5 7. Bb3 Bb7 8.
O-O e6 9. Bg5 Nbd7 10. Re1 Be7 11. Qd3 O-O 12. Rad1 Rfd8 13. a3 c5 14. dxc5
Qxd3 15. Rxd3 Nxc5 16. Rxd8+ Rxd8 17. Ba2 h6 18. Be3 Nd5 19. Nxd5 Bxd5 20.
Bxd5 Rxd5 21. Kf1 f6 22. Ke2 Kf7 23. Rd1 Rxd1 24. Kxd1 e5 25. Ke2 Ke6 26.
Nd2 f5 27. f3 Kd5 28. g3 g5 29. b4 Ne6 30. Kd3 Bf6 31. Nb3 Bd8 32. Nc5 Nxc5+
33. Bxc5 h5 34. h3 g4 35. fxg4 fxg4 36. hxg4 hxg4 37. Be3 e4+ 38. Kc3 Bf6+
39. Kb3 Be5 40. Bf2 e3 41. Bxe3 Bxg3 42. a4 Be5 43. axb5 axb5 44. c3 g3 45.
Bg1 Bf4 46. Bb6 g2 47. Bg1 Bg3 48. Kb2 Kc4 49. Kc2 Be1 50. Be3 Bxc3 51. Bc5
Bxb4 52. Bg1 Bc5 53. Bh2 g1=Q 54. Bxg1 Bxg1 55. Kb2 b4 56. Kc2 b3+ 57. Kb2
Bd4+ 58. Kb1 Bc3 59. Kc1 Kb4 60. Kb1 Ka3 61. Kc1 Ka2 62. Kd1 b2 63. Kc2 Bf6
64. Kd3 b1=Q+ 65. Ke3 Qf5 66. Kd2 Kb3 67. Ke2 Qg4+ 68. Ke3 Qd4+ 69. Kf3 Kc3
70. Ke2 Qd3+ 71. Kf2 Bd4+ 72. Kg2 Qe3 73. Kf1 Qf2# {White checkmated} 0-1
In this first game black only idea in the opening was to get a favorable endgame
with the better majority(4 vs 3). I used my better control of d file to trade
heavy pieces, then exchanges some others until I got not only the better
majority but also the good bishop. After 16. ... Rxd8 a good evaluation must
say: Black is much better +/- (not +/=). But only after 32. ... Nxc5 I would
evaluate the position as clearly winning for black.
[Event "ICC 4 0 u"]
[Site "Internet Chess Club"]
[Date "1999.06.08"]
[Round "-"]
[White "Helcio"]
[Black "wally"]
[Result "0-1"]
[WhiteElo "2405"]
[BlackElo "2639"]
[Opening "QGD: Charousek (Petrosian) variation"]
[ECO "D31"]
[NIC "QO.14"]
[Time "09:57:19"]
[TimeControl "240+0"]
1. d4 d5 2. c4 e6 3. Nc3 Be7 4. Nf3 Nf6 5. Bg5 h6 6. Bxf6 Bxf6 7. e3 O-O 8.
Qc2 Na6 9. Rd1 c6 10. a3 Qe7 11. h3 Nc7 12. Be2 dxc4 13. Bxc4 e5 14. dxe5
Bxe5 15. Nxe5 Qxe5 16. O-O Be6 17. Bxe6 Nxe6 18. b4 a5 19. Rd3 axb4 20. axb4
Rfd8 21. Rxd8+ Rxd8 22. Rd1 Rxd1+ 23. Nxd1 Qb5 24. Qd2 c5 25. bxc5 Qxc5 26.
e4 b5 27. Ne3 b4 28. g3 Nd4 29. Kg2 Qc3 30. Qa2 b3 31. Qa8+ Kh7 32. Qb7 b2
33. h4 Qb3 34. Qd7 b1=Q 35. Qxd4 Q3d3 {White resigns} 0-1
This one I lost because I evaluated wrongly the position after 13. ... e5
I thought I would get the better majority but this is completely wrong because
It's hard to exchange queens and although I had a3,b4 against a7,b7,c6 The
position was worse for me. Better would be 14. o-o and although after 14. ...
exd4 15 exd4 white has an isolated pawn he is better because he has more active
pieces and can play against c8 bishop(a bad bishop). It's clear that after 22.
Rxd1+ Black is winning easily... :(
When you understand well a theme like this one, you improve a lot your game and
so will if you implement it on a chess program. Perhaps an aproach to this would
be to have an aditional flag to say:endgame is good, exchange this type of
pieces... If you should use it in the evaluation and if so, what should be it
height on it is a more complex question.
Helcio Alexandre
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