Author: Uri Blass
Date: 02:35:40 01/07/05
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On January 06, 2005 at 19:53:58, Dann Corbit wrote: >On January 06, 2005 at 19:15:58, Pallav Nawani wrote: > >>On January 06, 2005 at 18:18:40, David B Weller wrote: >> >>>Hi Geoff, >>> >>>The fact that you stumble over my code is probably a credit to your >>>intellegence, and if I tried to explain: attack_mask[][], I would embarass >>>myself. >>> >>>In fact, while thinking over how to best answer your question, I too became >>>somewhat puzzled as to how what I did, actually improves GES performance. It >>>really is inacurate. >>> >>>The part I added is at the end of control.cpp and 1 line in evaluate.cpp : >>> >>>s += count_ctrl() * 3; >>> >>> the '3' is pulled from memory - I think Prof Hyatt used it for Bishop mobility, >>>but since what I am counting isnt the same, it is probably way off. WAY off. >>> >>>The basic idea of count_ctrl() is to detirmine who 'owns' each of the 64 >>>squares. But it is very simple and naive. It makes assumptions which are >>>probably true more often than not, but still wrong much of the time. eg., if >>>white has a pawn attacking a square, but black doesnt have a pawn attacking that >>>square - white owns the square. regardless of what else is attacking it. If both >>>have pawns attacking [or, niether do] then the same idea is applied for knights. >>>Then Bishops, then Rooks, then Queens. >> >>So what you are evaluating is board control. I had no idea it was that useful. >>Maybe I will try implementing that (after I have implemented attack tables, that >>is). > >A bitboard program will have a stupendous advantage here [considering again >Fabian's code]. > >If you look at the eval function (where he calculates mobility) with a bitboard >program you can precompute EVERYTHING and every single nested loop goes away. > >By a stupendous margin, all of his program's time is bottled up by eval(). > >If Fabian's program were converted to bitboard, it could run 5x faster. How's >that for a scary thought? Does Fruit use more than 80% of it's time for mobility evaluation. If it is not the case then I do not see where the 5x faster comes from. Even if it can calculate fruit's mobility evaluation 5 times faster it does not mean that the program will be 5 times faster. Uri Uri
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