Author: martin fierz
Date: 23:45:37 04/06/02
aloha! i have a whole bunch of questions tonight. the reason is that i will participate in a computer checkers tournament in august in las vegas, and would like to improve my chances a bit :-) the questions are the same as in computer chess, so i hope you can help me :-) 1) TB caching/access i just had my computer calculate the 8-piece db. in the meantime, it has also compressed it to about 4.5GB (20% less than the chinook db), and i'm working on the access code. at the moment, i use a circular buffer of database blocks, and run a pointer through the buffer and overwrite whatever is there if i find i have to access a block that is not already in memory. this works ok, but it seems that there are better schemes - LRU for example. could somebody explain how this works and how much better it would be (this is important to me! i'm such a lousy programmer that i'd rather not use doubly linked lists unless there really is something to gain - because i will certainly generate lots of bugs...)? or point me to a webpage explaining? also, at the moment i use VirtualAlloc to get myself a big address region which i use for my buffer. under windows, there are these memory-mapped files. would i do better to try to use memory-mapped files instead of virtualalloc? and if yes, my db consists of 1000s of files - can i map any number of files, or is there a limit? 2)timing i never had to do anything about the timing of my program before, except for fixed time per move. now, we will probably play game in X. is there some kind of standard way to allot time per move in this mode of play? a fixed percentage of the remaining time maybe? also on this issue: very often, there is only one plausible move in a position in checkers. i guess in chess this would be similar to a position where a piece has been taken and only one move takes the material back. i would like to make such "obvious" moves faster than "normal" moves. has anybody ever experimented with such a thing (e.g. in the root alphabeta call, do a normal search, and then do a minimal window search for moves 2-n with (bestvalue-X,bestvalue-X+1)as window and see if it fails low for all moves, for an X of say 2 pawns? and if yes, stop the search for example after half or quarter the nominal search time? 3) hardware rental the checkers tournament will take place in las vegas in early august. i have a XP1600+ with 1GB ram here in honolulu, but getting that tower to vegas with a monitor is a hassle. i searched for computer rentals on the net, but most have rather outdated hardware. does anyone know if there is a possibility to rent a really good system (e.g. a bit faster than mine, as much ram as possible)in las vegas for a week? cheers martin
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