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Subject: Re: takes shredder5 51 seconds to find mate in one

Author: Roy Eassa

Date: 14:45:03 09/27/01

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On September 27, 2001 at 15:53:35, Uri Blass wrote:

>On September 27, 2001 at 15:23:07, Roy Eassa wrote:
>
>>On September 27, 2001 at 14:52:46, Uri Blass wrote:
>>
>>>On September 27, 2001 at 14:14:07, K. Burcham wrote:
>>>
>>>>takes shredder5 51 seconds to decide on Qh1. 1500 mhz   amd
>>>>
>>>>Engine: Shredder 5
>>>>by Stefan Meyer-Kahlen
>>>>
>>>>
>>>>  1.00	 0:27 	+9.84 	1.dxe4 Rxd5 2.Rxg4 Bxc3 (5.687.141) 205.4
>>>>  1.00	 0:51 	  +M1++ 	1.Qh1+ (10.192.541) 199.6
>>>>  1.00	 0:51 	  +M1 	1.Qh1+ (10.192.542) 199.6
>>>>best move: Qa1-h1 time: 0:51.058 min  n/s: 199.642  nodes: 10.192.560
>>>>
>>>>kburcham
>>>
>>>New position
>>>[D]8/8/pppppppK/NBBR1NRp/nbbrqnrP/PPPPPPPk/8/Q7 w - - 0 1
>>>
>>>Analysis by Goliath Light 1.5:
>>>
>>>1.Qh1#
>>>  +-  (#101)   Depth: 4/31   00:00:15  2874kN
>>>1.Qh1#
>>>  +-  (#1)   Depth: 4/31   00:00:15  2874kN
>>>
>>>(Blass, Tel-aviv 27.09.2001)
>>>
>>>I do not understand the first mate in 101 score
>>>
>>>Deep Fritz's analysis after more than 10 minutes of search
>>>
>>>New position
>>>8/8/pppppppK/NBBR1NRp/nbbrqnrP/PPPPPPPk/8/Q7 w - - 0 1
>>>
>>>Analysis by Deep Fritz:
>>>
>>>1.dxe4!
>>>  +-  (1.56)   Depth: 1/2   00:00:00
>>>
>>
>>
>>Is there a simple, understandable reason why several "strong" programs take so
>>long here?  (Deep Fritz not seeing the mate in 1 after 10 minutes is
>>mind-boggling to me!)
>
>Yes
>
>Deep Fritz probably does a typical computer mistake
>of searching all the captures first.
>
>My guess is that one of the possible lines that
>Deep fritz searches is for example:
>
>1.dxe4 gxf5 2.Rxg4 fxg4 3.Bxd4 Bxa5 4.exf4 cxb5 5.Rxh5 Bxb3
>6.fxg4 Kxg4 7.Bxf6 Kxg3
>
>I guess that it is only one of the lines that Deep Fritz see
>before looking at Qh1#
>


I thought all programs searched everthing one ply first, then two ply, then
three, etc.  If there's a MATE at one ply, then it would find it in a tiny
fraction of a second, no matter which order it chose to look at the moves, no?
Or is it doing extensions on other moves, even at ply 1?



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