Author: Peter McKenzie
Date: 22:09:01 09/20/00
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On September 21, 2000 at 00:38:37, Mike Adams wrote: > I want to thank those who offered suggestions for null move in Pulsar, in >perliminary tests it seems to be worth 50 points to do depth-3 over depth-2. >Also it no longer does null move while in check. > Pulsar manages to win many games by blitzing its opponent with tactics but >its often comeing from behind in very unsound positions it gets itself into. It >will let its queen wander to other side of board while its king is under viscous >attack. It has been known to place its pieces in very awkward positions with >little room for movement. The evaluate basicly only looks a things like 64 >grid poitions bonuses for knights, bishops, pawns. pawn structure such as passed >isolated and double pawns, and rooks on 7th rank and open files. It also has a >little king saftey in that it tries to preserve the pawns around its castled >kings and there is a 25 point bonus for castling. I preety much modled the >evaluate after the simple chess program and have not gone beyond that. Its >playing at 2100 blitz at moment on icc but can still lose to much lower rated >opponents who maybe allign all pieces on king and make a sacraftice at critical >move. Are there some things I can do without getting overly complicated at least >not at first that would improve it postionally. For example is there any way i >can use the moves it generates in the evaluate function to look for things like >piece mobility or pieces threatening the king? I have added a check extension >which seems to be helping king saftey but it still kicks in often late. Any >suggestions would be appreciated. Hi Mike, the things that you describe are all the classic problems that most people face when developing a new chess program. Some of these things you can solve (or reduce at least) by improving your program's search, but others must be attacked by improving your evaluation. King safety is the classic, because there is nothing that the average 1500-2000 player on ICC loves more than sacrificing a couple of pieces to mate a higher rated computer. These guys will keep coming at you, often losing a bunch of games but then pulling off a spectacular win and sucking a few rating points from you. Its a great way of testing a program. The best defense I can recommend is to improve your king safety evaluation. This can be tricky but really pays off. There is lots of room for doing interesting things in the eval. You asked for something simple to try, well do you have a bonus for having your queen close to the enemy king? This is a very simple one, and a little too simple in some respects, but its something to play with for a start. Extensions help sometimes too of course, but must be very carefully tuned otherwise your search explodes. Good luck and have fun! cheers, Peter
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