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Subject: Re: Average Engine but a fascinating game !

Author: Ralph Stoesser

Date: 15:29:40 07/08/03

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On July 08, 2003 at 17:33:27, Alessandro Damiani wrote:

>On July 08, 2003 at 10:40:28, Uri Blass wrote:
>
>>On July 08, 2003 at 10:28:55, Djordje Vidanovic wrote:
>>
>>>On July 07, 2003 at 16:47:09, Uri Blass wrote:
>>>
>>>>On July 07, 2003 at 16:44:28, Djordje Vidanovic wrote:
>>>>
>>>>>Here's the clip from the newest Ruffian engine:
>>>>>
>>>>>New game
>>>>>4rqn1/p3brk1/R5p1/6Bp/1p5Q/1B1R4/PPP2PPP/6K1 w - - 0 1
>>>>>
>>>>>Analysis by Ruffian 2003-06-23:
>>>>>
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 1/7   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 1/7   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 2/7   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 3/10   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 4/10   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 5/11   00:00:00
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 6/13   00:00:00  16kN
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 7/17   00:00:00  86kN
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 8/20   00:00:00  202kN
>>>>>1.Rxg6+ Kxg6 2.Rh3 Bxg5 3.Qxh5+ Kf5 4.Rf3+ Ke5 5.Rxf7 Qh6 6.Qe2+ Be3 7.fxe3
>>>>>  +-  (7.53)   Depth: 9/20   00:00:00  448kN
>>>>
>>>>I suspect that it learned from previous analysis.
>>>>The line and the score was not changed from depth 1.
>>>>
>>>>Uri
>>>
>>>
>>>Which previous analysis?  I just copied the fen into Ruffian and let him
>>>analyse. No previous analysis. Wrong suspicion :)  Ruffian is a very smart
>>>program...
>>>
>>>Djordje
>>
>>It does not make sense that a program has a pv of 13 plies at depth 1 when the
>>pv and the score are unchanged until depth 9 except number of nodes.
>>
>
>It is possible due to extensions. At depth 1 the PV is extended 13 plies deep.

Doesn't mean the "7" from "Depth: 1/7" that it extended 7 plies only?


>The following iterations can produce the same pv and therefore the same score if
>the extensions at depth 1 already produced the best sequence of moves up to ply
>13.
>
>This behaviour happens also with a simple full-width search followed by a
>capture search: if at the horizon of the full-width search - on the pv - a
>capture is forced, the next iteration will have the same pv with the same depth
>and score.
>
>Rgds,
>Alessandro



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