Author: Peter Fendrich
Date: 07:43:05 03/23/04
Go up one level in this thread
On March 23, 2004 at 09:13:21, martin fierz wrote: >On March 23, 2004 at 08:59:04, Peter Fendrich wrote: > >>On March 23, 2004 at 04:51:18, Uri Blass wrote: >> >>>On March 23, 2004 at 02:24:38, Tony Werten wrote: >>> >>>>On March 22, 2004 at 19:21:42, Dann Corbit wrote: >>>> >>>>>On March 22, 2004 at 18:57:52, Uri Blass wrote: >>>>> >>>>>>On March 22, 2004 at 18:50:15, Dieter Buerssner wrote: >>>>>> >>>>>>>On March 22, 2004 at 18:16:37, martin fierz wrote: >>>>>>> >>>>>>>>of course i would also like to make an incremental update of that table, but i >>>>>>>>decided against such an attempt because i couldn't figure out how to do it - or >>>>>>>>rather, i devised a scheme for incremental updating which was so horribly >>>>>>>>complicated that i decided not to use it - i'd rather have a slow engine with >>>>>>>>little bugs and good maintainability than a fast engine with many bugs and low >>>>>>>>maintainability :-) >>>>>>> >>>>>>>Reminds me of: >>>>>>> >>>>>>>"Debugging is twice as hard as writing the code in the first place. Therefore, >>>>>>>if you write the code as cleverly as possible, you are, by definition, not smart >>>>>>>enough to debug it." Brian W. Kernighan >>>>>>> >>>>>>>At the moment, I don't use attack tables at all. But I want them again. And I >>>>>>>also only have a "build-from-scratch" routine. I also thought about incremental >>>>>>>updates, and it seems like a very hard job. And the bad thing is, they seem to >>>>>>>be especially useful at the leafs or close to the leafs. Perhaps I will start >>>>>>>again with using them only closer to the root, for pruning/extension decisions. >>>>>>> >>>>>>>Regards, >>>>>>>Dieter >>>>>> >>>>>>I update them incrementally. >>>>>>I can only give a hint that I simply have a function to update incrementally >>>>>>when I add a piece or delete a piece. >>>>>> >>>>>>I got this idea when I got the conclusion that having a function to update them >>>>>>based on a move is a very hard task. >>>>> >>>>>I think I have the same idea: >>>> >>>>You left out the interesting part: >>>> >>>>> >>>>>1. Lift the piece off the board, and remove all of its influence >>>> >>>>1b for every slider attacking the fromsquare, extend its influence >>> >>>You miss the idea >>> >>>All the idea is that I consider no from square and no to square in updating the >>>attack table. >>> >>>I look at a move as a sequence of add piece to square and remove the piece from >>>square and I have function to update the attack table when I add piece or remove >>>piece. >>> >>>Uri >> >>That doesn't change anything. >>When you remove the piece (the piece on the from-square) don't you extend the >>attackers to that piece (1b above) then? >>/Peter > >that seemed to be the big problem in incremental attack updating to me. you have >to remember the attacks for all sliders, and if either the from or the to square >of your move coincides with a slider attack, you have to update the attacks of >this slider. what a bother... > >cheers > martin Yes it is... Basically one need 4 functions: Insert_attacks_from(sq) Remove_attacks_from(sq) Extend_attacks_to(sq) Cut_attacks_to(sq) to be used for different moves. Then there are all the optimistaions that can be done! For instance a capture move to e4 doesn't need the Cut_attacks_to(e4). /Peter
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