Author: Robert Hyatt
Date: 19:09:54 08/27/00
Go up one level in this thread
On August 27, 2000 at 10:34:17, Uri Blass wrote:
>On August 27, 2000 at 10:05:17, Robert Hyatt wrote:
>
>>On August 27, 2000 at 00:28:08, Ed Schröder wrote:
>>
>>>On August 26, 2000 at 23:43:34, Robert Hyatt wrote:
>>>
>>>>On August 26, 2000 at 23:06:10, Ed Schröder wrote:
>>>>
>>>>>On August 26, 2000 at 21:08:37, Robert Hyatt wrote:
>>>>>
>>>>>>On August 26, 2000 at 11:05:24, walter irvin wrote:
>>>>>>
>>>>>>>On August 26, 2000 at 09:21:15, Robert Hyatt wrote:
>>>>>>>
>>>>>>>>On August 26, 2000 at 09:16:50, Uri Blass wrote:
>>>>>>>>
>>>>>>>>>I tried this position from the game century3-crafty17.11
>>>>>>>>>
>>>>>>>>>[D]rnbqk2r/pp1p1ppp/4pn2/4P3/1b1N4/2N5/PPP2PPP/R1BQKB1R b KQkq - 0 1
>>>>>>>>>
>>>>>>>>>Crafty17.13 played 6...Qc7
>>>>>>>>>
>>>>>>>>>I gave my Crafty17.11 as engine for Hiarcs with 128 Mbyes hash time control of 4
>>>>>>>>>hours/60 moves
>>>>>>>>>(I guess that this time control is similiar to 2 hours/60 moves on the alpha)
>>>>>>>>>
>>>>>>>>>My Crafty17.11 changed its mind in the last second at depth 12 from 6..Qc7(0.15
>>>>>>>>>pawn advantage) to the better move 6...Nd5(0.16 pawns advantage).
>>>>>>>>>
>>>>>>>>>I am interested to know crafty17.13's opinion.
>>>>>>>>>Can crafty17.13 avoid 6...Qc7 at depth 12?
>>>>>>>>>
>>>>>>>>>Uri
>>>>>>>>
>>>>>>>>
>>>>>>>>It avoids it by depth=10. The problem was that the mode we were using forced it
>>>>>>>>to play Qc7 as it was a book move. Somehow we followed a very rarely played
>>>>>>>>line, but until I get the log files from Graham I can't tell exactly why. I
>>>>>>>>did notice a pretty significant CAP score that might have pulled it down that
>>>>>>>>line erroneously...
>>>>>>>
>>>>>>>what was the speed relitive x86 for the alpha you used .would it have been
>>>>>>>faster if you could have gotten similar hardware that deep junior had at
>>>>>>>dortmund ??what nps was you seeing on the alpha .
>>>>>>
>>>>>>
>>>>>>We were doing about 400K nps. My quad xeon does about 1M, for reference.
>>>>>>
>>>>>>Speed wasn't the issue here however, it was simply following a bad book line
>>>>>>until it was too late...
>>>>>
>>>>>But 6..Qc7? came not from the book but from the Crafty engine. In this
>>>>>game the Crafty book did not work.
>>>>>
>>>>>Ed
>>>>
>>>>
>>>>No... it came from the book. We were using "book random 0" which says to
>>>>search (for a short time, normally) all the book moves, and play the one with
>>>>the best score. Qc7 was in the book, but the score fails low pretty quickly.
>>>>Then, after resolving the fail low, it decides "hey, this is bad, I am not
>>>>going to play a book move at all." It then does a normal search, but it had
>>>>used too much time and the search wasn't very deep....
>>>>
>>>>The book was actually working, but "book random 0" changes the way it looks,
>>>>and if you don't know, you could assume it is doing a normal search, unless
>>>>you see the line "searching only the following moves: {a b c d etc}
>>>>
>>>>I think Qc7 was the third most popular move in that very narrow (and bad) book
>>>>line...
>>>
>>>This is what I remember from our game: 1.e4 by Rebel and Crafty immediately
>>>replied with 1..c5 from the book. Then 2.Nf3 and then Crafty started to
>>>think shortly (5-10 seconds) and the second Crafty move was played. This
>>>behaviour (5-10 secons for the move) continued till move 5 or 6 and then
>>>Crafty started to use the normal 2-4 minutes for its moves. 6..Qc7 came
>>>at the last moment after a 2-4 minutes search. After 6..Qc7 Rebel was also
>>>out of book.
>>>
>>>I don't know that much about Crafty but everybody was saying Crafty was
>>>out of book after move 1. Also Graham said the above Crafty behavior was
>>>the same in game 1 (implied Crafty playing without book in game-1).
>>>
>>>Hope this gives you sufficient information to make up your mind what
>>>really went wrong with the book.
>>>
>>>Ed
>>
>>
>>That sounds like what I would expect here... If the score for Qc7 dropped
>>enough, it will refuse to play it as a book move and do a search. I had not
>>factored in the problem with a fail low at the end of the book search, which
>>could use over 1/2 of the total time allocated to this move. But I will cover
>>this hole quickly, of course. :)
>>
>>Qc7 was played several thousand times, however, which makes it surprising it
>>isn't in your book.
>
>Rebel does not need Qc7 in the book for the following reasons:
>1)it is a bad move.
>2)It is no problem for Rebel to win the game with white after Qc7 with no book.
>
It actually is a problem. IE a friend of mine has tried three different
commercial engines, and at short time controls, they choose moves like Nb5
and so forth. A couple find exf6 quickly, then change to something else,
then change back when they see it is good...
>If the book (or at least the part of the book that includes this line) is done
>manually and not generated automatically from human-human games it is logical to
>decide not to include this line in the book.
How do you do that manually? Any idea how many different book positions are
in a normal book? A million? And you manually choose which moves to exclude
from a database of positions that no human can possibly go through?
It isn't as easy as it seems...
>
>It is also logical not to include the line if you assume slow automatic
>generating of the book that means that every move is analyzed before you put it
>in the book.
How long to search? 3 minutes? For a book that has 1 billion possible
moves in the PGN games? How long will that take? 3 billion minutes? I
don't think I have that much time to do this. :)
>
>In this case analysis can show that Qc7 is not good and not put the move in the
>book(it is a waste of space to put replies to bad moves in the book when the
>computer can find the right contradiction to the moves at tournament time
>control).
It is less wasteful to include a reply to a bad move, than it is to search to
discover that the original move was bad. In my case, such a reply takes about
24 bytes. Which are essentially free at today's disk prices. VS 3-4 minutes of
cpu time, which is not so free.
>
>Uri
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