Author: Richard Pijl
Date: 03:07:30 10/11/05
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>>>Well, you know that is not true. >>>Rather than have a long thread and dialog with him, I was hoping that other >>>Programmers would agree about the Tree ..search function analysis mode etc. >>>I think that is a given, so we'll start from here. >>>It should be obvious that he who runs the fastest wins the race. >>>The Program/Engine that searches the deepest & faster in the alloted time, >>>finds the 'best' moves. >>>Would you agree? >> >>No >> >>A program may search deeper but still lose because of inferior evaluation. > >No, We disagree 100% The Program truly does evaluate 'every' possible move in >any position! It ranks them in order of the highest return from the Alpha Beta >& Mini/Max algorithim. The centipawn eval is based only on the static positional >factors programmed in. The program that searches the deepest in the >alloted time will find the better moves. >I don't understand why you don't understand this! A number of remarks on this puristic view: - You don't always need to generate all moves in a position to get a beta-cutoff (i.e. a move that is so good, that the opponent would not let you get there by choosing another move earlier in the game), e.g. by generating only capture moves. - Move scoring for move ordering is in principle not the same as evaluation of a move, although for some programs it might be. Many programs have a quite arbitrary ordering (e.g. history-heuristic) for non-capture moves. - In quiescense search usually only a subset of the possible moves are considered. The selection of those moves depend on the program but usually consists of the capture moves and some checking moves. >> >>Searching deeper is a clear advantage but computer chess is not only about >>searching deeper. > >It's exactly about searching deeper! It helps, but it is not the only thing, so again, I agree with Uri. It depends on what sacrifices you make in the correctness of your search to get deeper. You may search deeper for one line, settling for a shallower depth in another. The quality of the algorithms in a program to choose which lines to extend, and which lines to prune or reduce is influencing this in a big way. Additionally, many things can be seen in evaluation that would require a 10ply search or more. So knowledge in chess programs matter too. Saying that chess programming is only about searching deeper is like saying that F1-racing is only about engine power. It helps of course, but the rest of the car design is perhaps even more important. Richard.
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