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Subject: Re: DB vs Kasparov Game 2 35. axb5

Author: blass uri

Date: 08:36:44 11/23/98

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On November 23, 1998 at 09:37:25, Robert Hyatt wrote:

>On November 22, 1998 at 11:49:54, blass uri wrote:
>
>>
>>I did not ask for all the tree but only the tree up to the point that my
>>programs can see by search of 3 minutes that black has at least 1 pawn
>>advantage.
>>
>>This is clearly less positions
>>because if in the leaves it is -2.xx then Junior can see some moves before the
>>leaves that it is -1.xx
>
>
>ok... rather than 10 million pages, it might only be 1 million pages.  How
>would we get those to you?  :)
>
>what you are overlooking is the point that junior (and all the other programs)
>look at a fat, shallow tree.  IE how do you think a program like Crafty, doing
>300K nodes per second, reaches 12 plies in the middlegame, while Deep Blue,
>doing 1,000 times as many nodes per second, only reaches to 10-11 plies in the
>middlegame?  Because *they* are searching 10 times deeper than I am on most
>moves, thru their "singular extensions" (and other extensions).  We've already
>seen that in the Deep Blue vs Kasparov game two, Dark Thought and Ferret have
>searched axb5/Qb6 to depth 20 or 21 without seeing anything to cause it to fail
>low, yet we know deep blue did.  At 1/2 that depth.  So it might take a program
>like junior *fifty* plies to find what is going on there for all I know at
>present.  And if I could somehow give you a PV to get you down to the point
>where Junior sees this, it would be so deep, probably, that it would be easy
>to say "but this isn't the best move, white or black should try this instead.
>And we end right back up at square zero.
>
>There are just some things they can see at 250M+ nodes per second that we won't
>ever see...

we are discussing about deepthought 2 game and not about deeper blue
deepthought could not calculate 250M+ nodes per second

>
>
>
>>
>>>I don't have their "output" for this move.  As I said before, we sat at the
>>>same table playing this game at the 88 ACM event (I think).  I saw their output,
>>>they saw ours.  We both saw them fail high with a score > 2.0, while we were
>>>reasonably happy with our score...  until the roof fell in about 10 moves
>>>later... and their eval didn't vary by much for the entire sequence...  So I
>>>can't give you their output, since I don't have it (they were using a laptop
>>>to display their stuff).  I can only tell you what actually happened in the
>>>game.
>>
>>I believe that cray blitz lost because of a mistake that came after c5(maybe at
>>move 32 because I do not see what is wrong with 32.Bg5)
>>The fact that they have score>2.0 does not prove that they were right in the
>>evaluation.
>
>
>You'll have to believe what you want here.  I *know* that a program that doesn't
>do any selective forward pruning and which doesn't use null-move is *not* going
>to make that kind of mistake, except perhaps for some sort of horizon effect on
>the end where they can't actually take the piece due to a mate threat or some-
>thing more serious. But that's not the case in this position...

There can be a mistake in the evaluation function
They may evaluate -2.xx something that top programs evaluates as -0.xx

Uri



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