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Subject: Re: Why Can't My Program See This?

Author: James Thompson

Date: 07:15:28 10/21/00

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You're right.  I should have specified the mate was for white.  Thanks for the
clarification.

James


On October 21, 2000 at 03:07:41, James Robertson wrote:

>On October 20, 2000 at 15:25:26, James Thompson wrote:
>
>>Regarding your solution,  1.   Kg8 leads to mate in 10!  Why not some other
>>variation like 1.   Be4?
>>
>>James
>
>This position is mate for white. Insomniac gives Kg8 as the best reply, although
>still mated in 10.
>
>James
>
>>
>>
>>On October 19, 2000 at 22:07:42, Michael Neish wrote:
>>
>>>
>>>Hi,
>>>
>>>I wonder whether anyone might be able to explain why my program cannot see the
>>>solution to BT2630 #3 below
>>>
>>>[D]5r1k/p1q2pp1/1pb4p/n3R1NQ/7P/3B1P2/2P3P1/7K w - -
>>>
>>>The solution is 1. Re6, leading to the following tactics:
>>>
>>>1. Re6   Kg8
>>>2. Rxh6  gxh6
>>>3. Qxh6  f5
>>>4. Qxf8+ Kxf8
>>>5. Ne6+ forking King and Queen and gaining material.
>>>
>>>My program does not see this if it searches 8-ply deep, even though it is doing
>>>check extensions, and should therefore see it (I think) because there are two
>>>checks in the sequence.
>>>
>>>If I make it do a 9-ply search it does find the right move (but well over the
>>>time limit), and funnily enough, the PV that it gives (the correct one) extends
>>>to eleven ply (because of the two checks).
>>>
>>>So we're going from not seeing far enough at 8-ply, even though it should, to
>>>seeing further than you need to at 9-ply.
>>>
>>>The only strong program I have got, HIARCS 7.0, finds the move at 4-ply.  Some
>>>heavy-duty extensions at work here I think ...
>>>
>>>Thanks for any feedback.
>>>
>>>Mike.



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