Author: Uri Blass
Date: 08:39:41 10/19/04
Go up one level in this thread
On October 19, 2004 at 10:34:39, Tord Romstad wrote: >On October 19, 2004 at 04:15:19, martin fierz wrote: > >>On October 18, 2004 at 22:10:48, Zach Wegner wrote: >> >>>Going back into the main search is the cheap way out, IMO. >> >>i disagree. going back into the main search is the right way out IMO. let's say >>you duplicate your code in the qsearch for the case you're in check as you >>suggest. then you change something in the way you handle in-checks. => you have >>to change it in two places. a very bad idea... > >I agree with Zach here. There is really not a lot of code that needs to be >duplicated in the qsearch anyway. In both of my engines, the only special >code for handling situations where the side to move is in check in the >qsearch is that all legal moves are generated (rather than just captures, >promotions and checks), and that returning a stand pat score is not allowed. > >>the speed gain you get for your version is probably tiny - i admit that it will >>be faster. > >The speed gain could be quite big (at least in some positions) for engines >which extend single replies to checks. If you call the main search from the >qsearch when the side to move is in check, there is a risk that there is >only a single legal move, and that this move will be extended. This means >that you will stay in the main search for yet another ply, and search >all moves rather than just captures for one more ply _after_ the check >evasion. This can be quite expensive. It will probably help you find >some tactics more quickly, but I doubt that it is worth the cost. > >Of course it would be possible to work around this problem, but then it >might no longer be simpler to call the main search rather than handling >checks correctly in the qsearch. > >>but ease of implementation is much more important than a % or two in >>speed, IMO. most amateur programs are weak because they have bugs, not because >>they are slow. > >Here I agree, as you know. As long as you don't have any serious bugs, you >can afford to be slow, have very little chess knowledge, and still beat most >of the amateur engines. > >Tord The question is what is very little chess knowledge What you consider as very little can be more than most of the amateur engines. Uri
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