Author: Ricardo Gibert
Date: 12:47:12 09/17/99
Go up one level in this thread
On September 17, 1999 at 12:48:35, Robert Hyatt wrote:
>On September 17, 1999 at 11:44:06, Helcio Alexandre Pacheco wrote:
>
>>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.
>
>unless maybe both castled queenside? then black's majority turns into a
>distant passed pawn.. Although I assume you are factoring in distance to
>queening?
>
>
>>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.
>
>This is one I might not agree with. IE if the kings are at g1/g8, I would
>probably rather be white, although it wouldn't be clearly better for either
>as the white passer is farther away and requires that black's king immediately
>take off for the queenside to stop it, while the white king can try to
>infiltrate and win one or more black pawns...
>
>tough 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.
>
>Here I personally factor in king positions. With the pawns not advanced
>at all, it probably is a non-issue as you suggest.
>
I want to mention a few points about the "size" of a majority (in the sense that
for example a 4 vs 3 is "bigger" than a 3 vs 2 majority):
1) The pawn that Queens tends to be closer to the center when the majority is
"bigger" e.g. a 4 vs 3 Q-side majority will pass the d-pawn. Such a pawn is
easier to overtake by the defending K, because it is not as far away. Also,
after taking it, the K does not have as far to go to get back into play.
2) In general, it is faster to Queen with a 1 vs 0, than with 2 vs 1, which in
turn is faster than 3 vs 2, which in turn is faster than 4 vs 3.
These 2 reasons often make the "bigger" majority less desirable. Naturally, the
specifics can over ride the above 2 points e.g. The feasability of sacrificing a
pawn to improve the quality of the candidate or the "bigger" majority may
already be far along in its generation of a Q.
Another defect of 3 vs 2 and 4 vs 3, but not 2 vs 1 or 1 vs 0 is the
availability of a technique I call "taking a hostage". Example: W: Ke3, a3, b2,
g2 B: Ke5, a5, b5, c4. Black wants to decoy the white K and round up the g-pawn
for a draw. This would work if we remove the a-pawns from the board, but after 1
g3! b4 2 a4! white wins by taking the black a-pawn "hostage". Black would rather
eliminate the a-pawns, but white keeps them on so he has something to "do" after
rounding up blacks candidate. Now white will win the black a-pawn then Q his own
a-pawn.
>
>
>>
>>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...).
>
>But can either keep them there? If I push the pawns and make a passed pawn
>on the queenside, your king is definitely going to have to go over to stop it.
>Hence the decoy ability of a distant passer to win the game. But there are a
>lot of tempo issues to be sure.
>
>A more common case is white with pawns on a2/b2/c2, f2/g2/h2, black with pawns
>on a7/b7 and pawns on f7/f6/g7/h7. Trading into this position with black is
>_really_ asking for trouble, and if you move the kingside white pawns a bit
>(double two of them as mentioned earlier) then white gets a passer, black
>can't, and black probably loses.
>
>
>
>
>>
>>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... :(
>
>this is always a risk... particularly if you are thinking majority at move
>13. :) Because the middlegame is between you and victory, as always. I'm
>going to hold 'candidate passer' scores way down until material begins to thin
>out significantly, although I will always evaluate passed pawns highly. But
>even my normal passed pawn scoring is dependent on material present on the
>board..
>
>
>>
>>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
>
>
>Tough questions, to be sure... "outside passed pawn" was not really hard after
>I caught the obvious exceptions (opponent has a protected passer, etc.) But
>adding this is harder becuase this has to work in harmony with all the other
>positional endgame terms I have in Crafty, and if they get out of whack, it
>starts playing like a bozo, quickly.
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