Author: Roberto Waldteufel
Date: 22:32:38 06/18/98
Go up one level in this thread
Hi Don, Thanks for your detailed description of Cilkchess' MTD(f) implementation. Maybe I'll try it again at some point, but it sounds quite tricky to get right. I don't use a lazy evaluation (never have done), but then my normal evaluation is not very sophisticated. It only takes into account material, bishop pair, open/semi-open files near kings and attack counts on squares adjacent to kings. However, I also use a preprocessor which sets square values for all the chessmen based on those features of the position that are unlikely to change during the search, such as squares on which pawns would be passed, open/semiopen files for rooks, squares for rooks behind passed pawns, centrality etc. I have tried other things, but came to the conclusion that it is best not to attempt preprocessing features that may change frequently, since then the information is too often inaccurate at the leaf nodes. I seem to have achieved a fairly good balance between the things I evaluate in the evaluation function and those I preprocess, but there are many things I still need to consider, perhaps pawn structure is the most important omission at present. I would be very interested to know what were the features that Larry recommended for your preprocessor, and whether any of these things were later moved to the terminal evaluation to improve accuracy, albeit at the cost of some speed. Over the past couple of days I have ported my program from an old 16-bit DOS compiler to a much superior 32-bit compiler (alas, no alpha 64-bit technology yet, but Pentium 333MHz is not too slow), and in the process of optimizing my code for this new platform I have been re-examining the issue of divideing the evaluation effort between the preprocessor and the evaluation function with a view to expanding the positional features it considers. Best Wishes
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.