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Subject: Re: Problem with Rybka 1.01 ??

Author: Uri Blass

Date: 00:19:46 12/24/05

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On December 24, 2005 at 03:05:23, William Penn wrote:

>Vas,
>
>Sorry, "hanging" or "hung" was a poor choice of words. (I was a little bit
>despondent when I wrote that.) What that implies did not happen. The engine and
>GUI were still fully functional and active. There was no problem with the
>various operations.
>
>What I meant to say was that nothing further appeared in the analysis display
>window after about 9 minutes. The engine was still active. It just wasn't
>providing any more PV outputs at greater depths. Possibly it would have, if I
>had let it go for a longer time, but I doubt it.
>
>Actually in this position, there is no doubt that the best move was already
>selected after 9 minutes. The game is almost over, a quick win. In that case it
>looks like Rybka simply decided there is no purpose for further analysis. So it
>is not necessarily a bad behavior, it is just different compared to how other
>engines behave. Naturally we would like to see the analysis and PV outputs
>continue, but that's not essential if Rybka's primary objective is simply to win
>the game.
>
>---------
>
>I just ran the following long analysis in infinite mode which shows something
>different. The nodes and nodes/second numbers are behaving strangely after level
>20.01. It looks like the nodes counter is recycling to zero after about
>500,000,000 nodes by my estimate. We used to see something similar in the older
>CB engines. Easy to fix, they just had to make their counter able to count to
>bigger numbers. I would guess this happened because it looks like you tripled
>those output numbers for cosmetic reasons... :)
>
> (game#243)
>
>[D]5qrk/pp1r3p/n1p2p2/P1p1pNp1/4P2P/1P1PQ1P1/2P2PK1/R6R w - -
>
>Engine: Rybka 1.01 Preview 2 32-bit (704 MB) by Vasik Rajlich
> (run 3-PV for a few minutes)
>15     2:36   +1.31    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Qe8 38.Qd1 b6
>                       39.axb6 (16.943.250) 110
>15     3:18   +1.06    33.Ra4 g4 34.Rc4 h5 35.Rd1 Rg6
>                       36.Ra1 Kg8 37.Kh2 Qe8 38.f3 gxf3 (21.431.195) 110
>15     2:59   +1.03    33.Qd2 Nc7 34.hxg5 Rxg5 35.Qc3 Nb5
>                       36.Qc4 Nd4 37.Rh4 Nxf5 38.exf5 Qd6
>                       39.Qe6 Qd5+ (19.457.399) 110
> (then reduce to 1 PV)
>11.01  0:01   +1.32    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Ng7 38.Qg4 Ne6
>                       39.Rh6 Qe8 (195.954) 111
>12.01  0:02   +1.33    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Ng7 38.Qg4 Ne6
>                       39.Rh6 Qe8 (267.392) 110
>13.01  0:04   +1.28    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Ng7 38.Qg4 Ne6
>                       39.Rh6 Qe8 (513.071) 108
>14.01  0:12   +1.30    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Ng7 38.Qg4 Ne6
>                       39.Rh6 Qe8 (1.386.246) 110
>15.01  0:24   +1.22    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Ne6
>                       36.Rxg5 fxg5 37.Rh1 Ng7 38.Qg4 Ne6
>                       39.Rh6 Qe8 (2.608.983) 110
>16.01  1:29   +1.30    33.hxg5 Rxg5 34.Qf3 Rg6 35.Rh5 Kg8
>                       36.Nh4 Rgg7 37.Rh6 Nb4 38.Rxf6 Qd8
>                       39.Rc1 (9.846.132) 113
>17.01  5:49   +1.23    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Rxh5
>                       36.Qxh5 Ne6 37.a6 b6 38.Rh1 Qg8
>                       39.Qh6 Qg5 (38.723.297) 113
>18.01  12:09  +1.18    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8
>                       36.Rh6 Qf8 37.Rah1 Ne6 38.Kg1 Kg8
>                       39.R1h4 Qd8 (81.225.326) 114
>19.01  26:31  +1.14    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8
>                       36.Rh6 Qf8 37.Rah1 Ne6 38.R1h4 Kg8
>                       39.Kg1 Qd8 (178.202.522) 114
>20.01  46:03  +1.26    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8
>                       36.Rh6 Qf8 37.Rah1 Ne6 38.R1h4 Kg8
>                       39.Kg1 Qd8 (309.766.912) 114
>21.01  84:55  +1.22    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 Qg8
>                       36.Rh6 Qf8 37.Rah1 Ne6 38.R1h4 b6
>                       39.Qd1 b5 (35.438.207) 7
>22.01  184:10 +1.20    33.hxg5 Rxg5 34.Qf3 Nc7 35.Rh5 (188.955.970) 17
>23.01  554:16 +1.19    33.hxg5 Rxg5 34.Rad1 (46.840.269) 1
>
>WP

This is strange because 500,000,000 nodes or 600,000,000 nodes that are supposed
to be searched after 554 minutes are not enough to be bigger than 2^31 so I see
no logical reason for the number of nodes to do down.

If the real number of nodes is higher and in printing you divide them by 4 or 8
then I can understand it but I see no reason to do it.

Uri



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