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Subject: Re: A test position for chess programs(counting attackers-defenders)

Author: James T. Walker

Date: 09:13:42 01/14/99

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On January 14, 1999 at 11:35:34, blass uri wrote:

>
>On January 14, 1999 at 10:44:31, Laurence Chen wrote:
>
>>On January 14, 1999 at 10:12:44, blass uri wrote:
>>
>>>
>>>On January 14, 1999 at 08:49:37, James T. Walker wrote:
>>>
>>>>On January 14, 1999 at 07:36:07, blass uri wrote:
>>>>
>>>>>
>>>>>5rk1/1B6/4p1pp/2b3p1/3qP3/6P1/1P2QPP1/5RK1 w - - 0 1
>>>>>
>>>>>This is a position from the game Junior5-FM Boris Mariasin(The result was draw)
>>>>>
>>>>>Junior5 and other programs evaluating it as an advantage fo white because they
>>>>>do not know to count Attackers-Defenders
>>>>>
>>>>>Is there a progam with a more realistic evaluation (small advantage for black or
>>>>>at least less than 0.2 pawn for white)?
>>>>>
>>>>>Uri
>>>>Hello Uri,
>>>>I'm a very bad chess player so I don't understand what is happening in this
>>>>position.  I see that white is up a pawn which is about a point.  So where is
>>>>the advantage for black?
>>>
>>>The advantage of black is that the black pieces attack f2 and all the white
>>>pieces must defend f2.
>>>
>>>White has no plan to do a progress in the position when black can play h5,g4,h4
>>>with an attack.
>>>
>>>I am not saying that black is winning but the evaluation should be at least
>>>equality.
>>>
>>>The problem of computers is that they do not count attacker-defemsors of f2 and
>>>cannot understand that the fact that white is passive give black at least
>>>equality
>>>
>>>Uri
>>Uri can you prove this position is equal? Really, you are saying that because of
>>the opposite color bishops in the position. Yet, let me ask you then, what can
>>Black do? Black is down a pawn, and White has a passed pawn on the Queenside,
>>that is why the +1.xx evaluation. So the position is not equal, the assessment
>>is correct, because White can break the pin of f2 easily, and if Black attempts
>>to advance the Kingside pawns, it gets in big trouble, it exposes the King to
>>White pieces.
>
>White cannot break the pin easily
>The game was drawn after
>26.Ba6 Kg7 27.Bb5 h5 28.Bc4 e5 29.b3 g4 30.Bd5 h4 31.Kh2 Qc3 32.f3 gxf3 33.gxf3
>hxg3+ 34.Kxg3 Be3 35.Rh1 Bf4+ 36.Kg2 Rc8 37.Qf2 Be3 38.Qa2 Qc2+ 39.Qxc2 Rxc2+
>40.Kh3 Bf4 41.Bc4 and the sides agree to a draw.
>
>What white could do?

*Fritz has this at +.50 for white.  Nimzo calls it +.58 for white.  Since white
has a pawn up and poor position this seems correct to me.  The black e pawn is
weak and needs defending after Ba6 and then either Qc4 or Bc4.  Qc4 may force
swapping queens. Bc4 followed by b3 saves the b pawn.  There seems to be a lot
of chess to be played yet with options on both sides.  A +.50 advantage is not
winning,  it's just an advantage.  The fact this game ended in a draw is not a
surprise to me but in the mean time white still has the extra pawn.
>

>The only plan for white to get out of the pin is g4 g3,Kg2 but this weakens the
>white king.
>
*Very seldom in chess is there a "only plan".  I don't understand the Kg2 since
g2 has a pawn on it.

>After g4 Junior wants to play Rb8 and black gets the pawn back.

*If the rook moves off the f file that kills the pin(Attackers vs Defenders).
Jim Walker


>Uri



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