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Subject: Re: can a program see this perpetual check?

Author: Howard Exner

Date: 19:59:50 06/03/99

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On June 03, 1999 at 01:51:04, blass uri wrote:

>2R5/p3k3/1p2qrpp/1P2Q3/8/4PP1P/5K2/8 w - - 0 1
>
>This position is from the ssdf games
>
>Junior5(P200) did a mistake 62.Qb8 and Rebel8(P90) forced a perpetual check by
>Rxf3+ 63.Kxf3 Qxh3+ 64.Kf2 Qf5+ 65.Ke1  Qb1+ 66.Kd2 Qb2+ 67.Kd1 Qb1+ 68.Ke2
>Qxb5+ 69.Kd2 Qb4+ 70.Kd3 Qb3+ 71.Ke4(The evaluation of Junior when it played
>71.Ke4 is 0.00 and Fritz can see the perpetual even earlier but not at move 62)
>
>I think that white has good chances to win after 62.Rc7+ with trading queens
>instead of 62.Qb8
>
>Can a program find 62.Qb8 or find a better defence for white to prevent the
>perpetual check?
>
>I think that it is a perpetual but I was too lazy to do a table of positions
>that white cannot escape from them without losing the rook or the queen.
>
>Uri

As always I enjoyed playing over the position you posted. As a player of the
white side I probably would have played Rc7+ followed by exchanging the Queens.
1. Rc7+ Kf8 2. Qxe6 Rxe6 3. f4.

Here I would cross my fingers and hope that my opponent would play Re7.
Because the white b pawn holds back the two black pawns exchanging rooks on e7
would be a simple win for white. Black would have to try and hang on with
some other move like Re4, Rf6 or g5 (I don't know exactly where these 3 moves
would lead to but they seem better than Re7?). Rook endings are tough to grind
out a win but leaving the Queens on always permits the drawing with perpetual
check as you have pointed out.

Here is the epd for black to play and avoid Re7.

5k2/p1R5/1p2r1pp/1P6/5P2/4P2P/5K2/8 b - -

What do computers do here? I know that sometimes these transitions to
King/pawn endings are problematic for computers.



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