Author: blass uri
Date: 12:02:09 06/24/00
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On June 24, 2000 at 13:58:26, leonid wrote: >On June 24, 2000 at 02:00:49, blass uri wrote: >>I am not sure if I understand you. > >Ura, think about initial position on the chess board, as the most simple >example. Final result if too far away. So, if you will do your calculation 5 >moves ahead, you will have 20 moves of the same value as final result. Second >stage (when you don't use openings) will help you to make the chose between >them. Alpha beta will not tell you that there are 20 moves with the same value. Suppose Na3 is the first move you start to search. alpha beta will tell you that Na3 gives equality and when the program(what you call logic) analyzes other moves it will only prove that they do not give white more than equality so only material evaluation will not tell you if they have the same value or worse value. It is only going to give you information if there is another move that wins material > >>Do you say that you first evaluate material and if the evaluation is equal you >>start to check between the equal moves which move is best by positional >>evaluation. >> >>If you do it you do not use the alpha-beta because the alpha-beta gives you no >>idea about the second best move[my opinion is that using alpha beta in the first > >Alpha-beta can give you very often as much as 15 moves of equal value in the >first half of usual game. I speak all the time about what I call "positional >logic". Alpha beta never gives you more than one move with a value and other moves that you know that they are not better and you have no idea if they are equal or worse. Minimax can give you 15 moves with the same value but not alpha beta. As I mentioned it before, multiplicity of the response is the main >problem when you want to know efficency of your positional logic. More judicial >choice between those moves can give the impression that one logic is better that >the next one. All difference could be only in second stage, if other program >work in the same way. Surprises are all the time possible. I did all my >programming alone. Very often when I spoke with other programmers I found that >they can hardly understand what I am been talking about. The main reason is that you do not explain yourself clearly. For example you say logic when you mean program and you do not change it even after people correct you. Nobody else except you is using the name logic for a chess program. Before I expected that >all chess programs end sooner or later by the same main structure. But it is not >what I see in reality. > >>plies is not a good idea because it is important to have an idea about the exact >>evaluation to know better which lines to analyze(I see cases when programs >>analyze moves that lead to mate in 1 because they do not reject the moves that >>they analyze for the right reason) but you should use alpha beta most of the >>time]. > >I don't speak about bugs in the logic. I speak how it must work in general >situation. > >Leonid. I did not speak about bugs but about alpha beta but it seems that you do not understand what is alpha beta if you say that it can give you 15 moves with the same value. Uri
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