Author: Matthew White
Date: 17:23:03 05/29/03
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On May 29, 2003 at 19:42:28, Russell Reagan wrote: >How do you keep the endgame book from growing out of control? For instance, most >"book endgames" that I know of are not concrete positions. They are a type of >position, with certain features. An example is K+P vs K. There are almost two >hundred thousand configurations on the board for this one simple ending, but the >ending boils down to a handful of rules. > >In rook endings there are certain positions that are "key positions", but if you >store every position that contains the key elements, you'd basically end up with >endgame tablebases, as far as I can tell. I think something different is >required. When I think of a "book", I think of a "collection of positions", and >it is not realistic to store all of the positions necessary for these "key >positions", because as you already mentioned, the current state of the art >doesn't allow that yet. > >You don't really care so much about the particular position. You care about the >positioning of the pieces relative to one another. This kind of reminds me of >partition search, which is a kind of special transposition table. Maybe >something like that could be used for an endgame "book". Other than that, maybe >pre-processor knowledge, or just adding the knowledge to the evaluation >function. K+P vs. K is already in tablebases. I am not really interested in finding a replacement for tablebases, rather finding a way to improve endgame performance. At this point, I am merely brainstorming. You mention that it is unrealistic to store all of the positions necessary for key positions. However, many of us have hundreds of megabytes (maybe even a few gigabytes) worth of opening book sitting on our hard drives. Wouldn't it be an effective use of space to build an endgame tree just like the opening tree? In certain openings, one player is playing for an endgame advantage. If a computer doesn't realize that they are playing for an endgame advantage, they will avoid trades and try to find a middlegame win. This can lead to big problems. However, if the hash table contains a position from the endgame which is a known win, and a quiescence search hits that position, the computer will know it is safe to seek an endgame. I believe that the endgame book would also prove smaller than an opening book in most cases, since there are often forced moves. This is a luxury that opening books don't usually have. I agree that many endgames are a pattern, and cannot be captured in book form. However, there are probably as many endgames that just need brute calculation. Certain openings inevitably lead to certain endings. I am not proposing a total endgame substitute, where the book will just take over whenever and endgame is reached... it is more like a crutch. Matt
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