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Subject: Re: Rybka's analysis is scanty

Author: Vasik Rajlich

Date: 10:04:12 12/10/05

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On December 10, 2005 at 07:57:16, Uri Blass wrote:

>On December 10, 2005 at 05:24:19, Vasik Rajlich wrote:
>
>>On December 09, 2005 at 15:24:03, Uri Blass wrote:
>>
>>>On December 09, 2005 at 14:52:41, Vasik Rajlich wrote:
>>>
>>>>On December 09, 2005 at 11:50:42, William Penn wrote:
>>>>
>>>>>Rybka's analysis is fairly short to begin with, compared to most other engines.
>>>>>It reaches its maximum after a few seconds, then it decreases at longer times.
>>>>>For example here's an analysis of a position in infinite mode using the Shredder
>>>>>Classic GUI. After 3 hours it is already showing a decrease of move information,
>>>>>which decreases even further after 10 hours. The specific position doesn't
>>>>>matter. I see this same pattern when analyzing any position for a long time.
>>>>>
>>>>>Engine: Rybka 1.0 Beta 32-bit (704 MB) by Vasik Rajlich
>>>>>12.01  0:03   +1.35    32.h4 g4 33.h5 Qf8 34.Qe2 Nb4 35.Rh4 Qe8 36.Ne3 (300.979)
>>>>>87
>>>>>13.01  0:06   +1.37    32.h4 g4 33.h5 Qf8 34.Qe2 Nb4 35.Rh4 Qe8 36.Ne3 Qe6
>>>>>(552.306) 90
>>>>>14.01  0:15   +1.36    32.h4 g4 33.h5 Qf8 34.Qe2 Nb4 35.h6 Qf7 36.Qd2 Qe6
>>>>>(1.362.839) 90
>>>>>15.01  2:02   +1.34    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6 36.Rxg5 fxg5
>>>>>(9.586.923) 80
>>>>>16.01  3:01   +1.31    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6 36.Rxg5 fxg5
>>>>>(14.741.441) 83
>>>>>17.01  5:30   +1.27    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8 36.Rh4 Ne6
>>>>>(27.355.485) 84
>>>>>18.01  10:34  +1.19    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8 36.Rh4 Rg6
>>>>>(52.200.357) 84
>>>>>19.01  18:28  +1.25    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8 36.Rh4 Rg6
>>>>>(90.818.525) 83
>>>>>20.01  42:12  +1.13    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8 36.Rah1 Ne6
>>>>>(200.052.005) 80
>>>>>21.01  92:04  +1.18    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8 36.Rah1 Ne6
>>>>>(427.366.814) 79
>>>>>22.01  174:11 +1.14    32.h4 Qf8 33.hxg5 Rxg5 34.Qf3 Nc7 (789.072.165) 77
>>>>>23.01  634:58 +1.24    32.h4 Qf8 33.hxg5 (2.860.235.585) 76
>>>>>
>>>>>WP
>>>>
>>>>This is intentional and can _very_ easily be fixed. Please send me an email if
>>>>you have a strong opinion about the matter.
>>>>
>>>>In my opinion, other engines talk too much. The ends of the PVs tend to be
>>>>pretty silly.
>>>>
>>>>Vas
>>>
>>>I think that they do not talk enough.
>>>
>>>I think that it is productive to have an option to see more for correspondence
>>>games like hash moves that you already remember at small depth for every move.
>>>
>>>I will be happy if rybka can write them to a text file.
>>>The point is that one problem in analysis is that a program may suggest line
>>>1.xx yy after many hours of search and you may need hours to see the reason that
>>>it rejected 1.xx zz because 1.xx zz is not the pv line
>>>
>>>If the program can print to a text file  the first move that it tries in the
>>>first 3 plies then it may be productive.
>>>
>>>Example in the opening position suppose the pv is 1.e4 e5 2.Nf3 Nf6 3,Nxe5
>>>
>>>I would like to see in text file something like
>>>1)the following 19 lines for depth 2
>>>1.d4 d5
>>>1.c4 e5
>>>...
>>>2)the following 19 lines for depth 3
>>>1.e4 a6 2.d4
>>>1.e4 a5 2.d4
>>>...
>>>
>>>If I do not see it then I may need a long analysis to understand why the program
>>>rejected 1.d4 for white or may need a long time to understand why the program
>>>rejected 1.e4 a6 for black
>>>
>>>Note that it may be productive also to have lines at bigger depth for thinking
>>>lines that the computer considered for a long time and if the program considered
>>>1.d4 d5 2.Nf3 for a long time then I would like to see the hash move after these
>>>moves in order to understand why it rejected 1.d4 d5 2.Nf3 for white.
>>>
>>>Uri
>>
>>Uri,
>>
>>this is a response also to your email, as well as a number of other emails I got
>>about this.
>>
>>In the short term, an engine can only display a PV, and this PV can only be
>>slightly shorter or slightly longer. This doesn't give the engine programmer
>>much leeway, and I think we all agree that a long single search isn't a very
>>useful use of many hours of computer time.
>
>I do not agree here.
>
>many hours of computer time may be useful  because the program may find a move
>that it does not find in a different way or find a win that it does not find in
>a different way(and knowing that there is a win in some position can be
>productive for analysis).
>
>The point is that a similiar win may be available in a different line and if you
>do not understand the reason that the program shows a winning score you may miss
>the second win in analysis.
>

If you invest several hours of computer time, you should be able to get a good
first move _and_ some additional analysis and information.

>
>
>
> Anyway I have now changed the
>>behavior so that the PVs at least continue getting longer as more time is spent.
>
>Thanks
>this is better(note that very long pv is not very impoertant but it is important
>to have more than 3 plies on the pv because even the program may need a long
>time to find the 4th move or the 5th move of the pv so you may be unable to use
>short analysis to find it later).
>
>>
>>In the long term, we should be able to instruct a chess package to spend several
>>hours analyzing a position and giving us a full report.
>
>I agree
>
> There are already some
>>implementations of this, mostly at the GUI level, which is where they belong. In
>>principle, these features should be better.
>
>Here I do not agree and I think that the engine should do it.
>I think that better analysis should also lead to better move(otherwise it is not
>better analysis)
>

In the really long term, yes, the engine should do it. For example, the engine
can search classically and in addition also play a bunch of games, and use the
results of the games to determine the best move.

That will be really intelligent analysis.

In the medium term, I think it's just a job for the GUI.

>If you think that different algorithm is better for analysis then it should be
>used also in playing games.

A different algorithm may give on average a worse first move, but provide better
alternative information for a human user.

>>
>>Some ideas in this direction:
>>
>>1) The GUI makes a package report about the position - deep analysis of a number
>>of lines, as well as a number of "shootout" games together with statistics.
>>Everything should be as automated as possible.
>
>If automatic deep analysis of number of lines is productive(I believe that it
>can be productive) then it should be used also in games and the program should
>tell the user the intereting lines that it found.
>
>Having exact score for second best move at least in the first plies may be
>productive also in games(for example it may allow the program to have better
>time managament and play immediately when second best move lead to forced mate
>against itself).
>

I think we're quite far from things like this being something which increase
engine strength.

>I agree that it may be productive if the engine respond to the user of the input
>that can tell it that some position is drawn but I think that in most positions
>the user does not know important details like that so the main advantage for the
>user is by fully automatic analysis and report with no conditions by the user.
>

Maybe it's not extremely frequent but it's very annoying when it happens.

Vas

>Uri




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