Author: Dann Corbit
Date: 10:31:53 05/20/99
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On May 19, 1999 at 20:55:40, Eugene Nalimov wrote: >I'm participating in that thread because I'm curious: how much we can "squeeze" >the average position. Unfortunately, I don't see who will implement suggested >algorithms and where it'll be used. > >To speak more generally, I can see 3 different goals for such the algorithm that >results in 3 different representation requirements: >(1) To store the entire game in the least possible # of bits. Here, as it was >pointed earlier, you'd better store starting position (if necessary) and >sequence of moves. >(2) To store the random position in the *fixed* number of bits, so that the >resulting file (database?) can be directly indexed. That means you have to >optimize the worst case. And here majority of the clever tricks (e.g. using less >bits for pawns or pieces on the 1st/8th ranks) will not work. IMHO, that >representation must be able to cover even the pathological cases that cannot >happen in the real games. >(3) To store the *average* position in the minimum amount of bits. That >representation can work if you plan to use only sequental search through those >positions. And here is the place of KarinsDad's schema - *average* position will >be stored significally better than by using the algorithm from the case (2). I think I should make clear why I brought it up in the first place. For *my* purposes, I do not necessarily need the very smallest conceivable. I just want something very small and very fast and easy to understand. It will be used to take a few hundred thousand EPD records and create an in-memory table for lookups. Hence, it has to work in the general case. I looked over some common schemes and just wanted to make sure that I was not overlooking something important that could save a lot of space. To store games, you could use a scheme like pigbase which only needs one byte per position. But I don't want that. I need to be able to access a random position that may not even be connected to other positions.
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