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Subject: Re: Easy for humans

Author: Miguel A. Ballicora

Date: 21:33:56 02/17/02

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On February 17, 2002 at 12:03:18, Uri Blass wrote:

>On February 17, 2002 at 11:43:09, Christophe Theron wrote:
>
>>On February 17, 2002 at 11:34:40, Christophe Theron wrote:
>>
>>>On February 17, 2002 at 05:43:22, Uri Blass wrote:
>>>
>>>>On February 17, 2002 at 05:21:47, Ed Schröder wrote:
>>>>
>>>>>On February 17, 2002 at 04:55:13, Steffen Jakob wrote:
>>>>>
>>>>>>Here is another position which is easy to solve for humans. In a blitz game
>>>>>>between Hossa and Arasan the following position was on the board:
>>>>>>
>>>>>>[D]8/8/4B2p/2K5/r5P1/p5k1/Rb6/8 b - - 7 116
>>>>>>
>>>>>>For humans it's rather easy to see that 117... Rxg4 wins without any problems
>>>>>>because the white rook is totally paralyzed. Unfortunately Hossa wasn't able to
>>>>>>see this in the blitz game. So the game continued until the 50 moves rule forced
>>>>>>Hossa to take the bishop and finally to win the game.
>>>>>>Which engines find 117... Rxg4 in which time?
>>>>>
>>>>>Easy for comps too :)
>>>>>
>>>>>2 secs for RC4
>>>>>
>>>>>Ed
>>>>>
>>>>>==============================================================
>>>>>
>>>>>00:00:02.1	1,88	9	449751	Re4 Kd6 Re3 Bf5 Kf4 Be6 Re5 Bd7
>>>>>00:00:02.1	1,88	9	817955	Rxg4
>>>>>00:00:02.1	2,09	9	835992	Rxg4 Bxg4 Kxg4 Kd5 h5 Kd6 h4 Kd5
>>>>>00:00:03.3	2,17	10	1122788	Rxg4 Bxg4 Kxg4 Kd5 h5 Ke4 h4 Ke3
>>>>>00:00:04.5	2,01	11	2027319	Rxg4 Bxg4 Kxg4 Kc4 h5 Kd3 Kf3 Kc4
>>>>>00:00:34.6	3,62	12	31107270	Rxg4 Bd7 h5 Bc6 Rf4 Kb5 h4 Ka5
>>>>>00:00:44.1	3,82	13	41624594	Rxg4 Bd7 h5 Bc6 Rf4 Bb5
>>>>
>>>>
>>>>Trivial for Deep Fritz
>>>>
>>>>It knows that opposite color bishops with one pawn advantage gives good chances
>>>>for a draw so it's only choice is to sacrifice the rook by evaluation.
>>>
>>>
>>>Where do you see an opposite bishops ending after Rxg4 Bxg4 Kxg4 ?
>>>
>>>
>>>
>>>    Christophe
>>
>>
>>
>>Oops... Sorry.
>>
>>OK, I've got it now. It's opposite colored bishops BEFORE the above capture
>>sequence.
>>
>>I did not get it at first because Tiger does not consider opposite bishop
>>endings as drawish when there are other pieces on the board (like rooks).
>>
>>Looks like I really should have a second look at this rule... :)
>>
>>
>>
>>    Christophe
>
>with rooks on the board there are better chances for a win for the stronger side
>but I believe that the chances for a draw are still better than the chances for
>a draw in case that there are no opposite bishops.
>
>Note that even with only bishops on the board it is not always a draw and I won
>my last game in the israeli league thanks for the fact that I did not accept a
>draw offer when the material was equal
>
>Here is the relevant position
>
>[D]6k1/6pp/p1b5/5p2/5P2/3p2P1/PP5P/4B1K1 w - - 0 31
>
>the last move of my opponent was Bb5-c6 and he offered me a draw
>
>I said no after some minutes of thinking because I found chances for a win
>and the game continued Kf2 Kf7 Ke3 Be4 Kd4 and only at this point my opponent
>understood that he has some trouble and started to think more than few seconds
>for a move.

This position looks pretty drawish. I think that Be4 is a waste of time.
The right plan is to get the king to the center and be prepared to blockade a
possible passed pawn (Q side) and defend the K side with the bishop.

Regards,
Miguel

>
>He wasted most of his half hour only to play Ke6 and later could not find the
>best moves and lost the game.
>
>Uri



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