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Subject: Re: Who can find the draw?

Author: Jeremiah Penery

Date: 13:53:23 01/31/00

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On January 31, 2000 at 16:28:42, Howard Exner wrote:

>On January 31, 2000 at 13:32:52, Jeremiah Penery wrote:
>
>>On January 31, 2000 at 12:00:02, Will Singleton wrote:
>>
>>>On January 30, 2000 at 23:02:32, William Bryant wrote:
>>>
>>>>On January 30, 2000 at 19:23:33, Will Singleton wrote:
>>>>
>>>>>Amateur-Lambchop was a pretty good game today at the ICC tournament.  Vincent
>>>>>pointed out that I missed a draw, and it looks like he was right.
>>>>>
>>>>>What programs see this? (w/o tablebases, which I assume would kick in)
>>>>>
>>>>>[D]3r4/8/8/P5R1/1K1pk2p/8/7P/8 w - -  bm Rg4+
>>>>>
>>>>>Will
>>>>
>>>>Will,
>>>>
>>>>I ran this in the current version of Screamer (which does not have table bases,
>>>>yet) and did not find a draw at 15:00 which is way beyond tournament time
>>>>controls.  Screamer could not decide between the moves Rg4+, a6, Kc5, and Kb3.
>>>>It ultimately settled for Kb3 with about at  -2.79.
>>>>
>>>>MacChess also switched between Rg4+, a6, Kc5, Rg1.  It also didn't find a draw,
>>>>but I stopped between 2 and 3 minutes which I guessed as the move time.
>>>>
>>>>I would love to see the PV.  I am assuming that tablebases make it easy (easier)
>>>>to see this?
>>>>
>>>>William
>>>>wbryant@ix.netcom.com
>>>
>>>I assume that with the tablebases, a program could trade off its rook for the
>>>two pawns, and then see the draw.  But I don't know if TB probes are typically
>>>made at the root, or a couple ply into the search.
>>>
>>>The idea is to play Rg4+ Ke3 RxP d3 Rh3+ Ke2 RxP RxR and then the a-pawn has to
>>>be stopped by the rook, which is a draw.
>>
>>After Rg4 Ke3, my modified Crafty (with TBs) could find the draw.  However,
>>after Rg4 Ke5!, Rxh4 no longer works.  It's _really_ difficult to find a draw
>>now.
>
>1. Rg4+ Ke5 2. Rxh4 d3 3. Rh5+ and white has to continue with the checks on the
>h file until of course black moves the king to the g file. But when that happens
>white plays moves like Rh7 or Rh3. Then follows d2 Rg7+(Rg3+) K f(whatever)
>R g1.I'm still getting a draw. Black misses a win
>by one tempo as after the eventual exchange on d1 the black King is on the f
>file.

1. Rg4+ Ke5 2. Rxh4 d3 3. Rh5+ Kf4 4. Rh4+ Kf5 5. Rh5+ Kg4 6. Rh7 d2 7. Rg7+
Kf5, and black wins - E.g., 8. Rg1 d1=Q 9. Rxd1 Rxd1, and black has mate in 27
by TB.



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