Author: Vincent Diepeveen
Date: 15:28:21 10/09/00
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On October 09, 2000 at 06:09:53, Steve Maughan wrote: >Having managed to add all the normal stuff to my chess program (hash, SEE >sorting, null move, killers, internal iterative deepening etc) I am a little >disappointed with the depths it is reaching. At first I thought it must be poor >move ordering but I've checked that and it seems OK (I do Hash Move, Good >Captures, Killer1, Killer2, History, Bad Captures). I decided to see how long >it took to complete it's nineth ply search from the initial position. Here are >the results along with those of other programs (450 MHz P2): I'm not so sure you can say that you're ok or doing bad. Openingsposition is a big big exception. suppose that you get huge score for center pawns and knights on f3. Try it simply. Try for a small test to increase the bonus for a knight on f3 by 0.2 pawn, a pawn on d4 with 0.2 pawn idem for black. Now rerun the test and how many nodes do you need then? I bet millions less. In fact i'm pretty sure that this can convince you that openingsposition isn't a very good test to do. A big initial trick for move ordering is to generate king moves as last moves, but castling if possible as first. As soon as the boundschecker is a bit finished under linux i'll produce some DIEP outputs. Note that this is with adaptive double nullmove. So first few plies R=3 then R=2, but for initial position that doesn't matter too many nodes. >MyProgram 31 secs 6,486,200 nodes >Ikarus 15 secs 888,000 nodes >HIARCS 18 secs 677,000 nodes >Faile 50 secs 3,500,000 nodes >Crafty 17.11 8 secs 800,000 nodes >Goliath Light 0 secs 31,000!!!! >Nimzo 7.32 13 secs 3,260,000 > >A couple of points. Firstly, how on earth can Goliath search 9 ply so quickly >and using so few nodes? I can't beleive that Goliath is the most selective. big scores for a few pawn moves and knights and you are at iteration 20 before you know it. In case of goliath i'm quite sure it's pruning a lot last n plies. Also it's a very fast program (?). >Secondly, it would seem that Ikarus' nodes / sec are much lower than indicated >when calculated using nodes visited divided by time! >Finally, for my program what am I doing wrong? Am I missing something? What >other forms of selectivity are coming into play here? I'm just doing a vanilla >Alpha / Beta but it's taking me ages (6 million nodes) to complete 9 ply. >Perhaps Bob could shed some light on Crafty's impressive 8 secs and only 800 kn. I bet he's gonna mention he's not doing checks in qsearch, but you didn't see DIEP output yet, note that diep's not optimized for openings position. I get it out of book always in 0 nodes searched :) > Could it be my poor evaluation funtion which is only a primitive piece-square >table? > >All help appreciated! > >Regards, > >Steve Maughan
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