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Subject: Re: Crafty Book Implementation

Author: David Rasmussen

Date: 03:00:44 06/12/01

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On June 11, 2001 at 20:48:19, Robert Hyatt wrote:

>On June 11, 2001 at 14:17:37, David Rasmussen wrote:
>
>>Am I an idiot, or does that Crafty book scheme miss some transpositions, because
>>of it's clustering system? Wait, those two statements aren't mutually
>>exclusive...
>>
>>When some of the upper bits of the book hashkey, is from the parent position,
>>doesn't that mean that if I'm in an unknown position, that can make a move that
>>transposes into a book position, it won't, because the upper bits will only
>>match the actual parent position(s) from when the book was created?
>>
>>I'm having an idea of another book implementation that I think is quite smart,
>>but I won't reveal anything yet, primarily because I don't know if it works in
>>practice, secondarily because it might not be a new idea, tertiarily because it
>>might not be a smart idea at all :)
>
>
>I _intentionally_ want to miss those transpositions.  One classic:
>
>1. e4 e5 Nf3 a6 Bb5.  Do you _really_ want to transpose back into the book
>and play Nc6?  Or do you want to rip the bishop and be a piece up in a won
>game?
>
>:)
>
>My thinking when I did this scheme was "Crafty will probably play Nc6 if it
>is reasonable, and _then_ we will transpose back into book after white plays
>Ba4, because that is a normal position.  But the position given above is
>"not normal" and I won't try to transpose.
>
>It has happened in _real_ games in the past.  But it won't happen to me
>here. :)

But still, you're saying: "I'm afraid of that situationm so I won't do _any_
transpositions from non-book positions to book positions", which is not as nice
as being able to do it from everywhere, while still taking care of the problem
you mention. I don't have a solution for this, but don't you think a solution
with those properties would be nicer?



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