Author: Ross Boyd
Date: 15:37:50 10/16/03
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On October 16, 2003 at 11:01:56, Tord Romstad wrote: >On October 16, 2003 at 10:29:25, Ross Boyd wrote: > >>Hi Tord, >>After adding EGTB support to TRACE her rating improvement was barely measurable. >>I think it was 6 elo after at least 200 games. >>And she is definitely an engine that lacks endgame knowledge. :-) > >I added tablebase support in Gothmog last week, but haven't tested the >improvement yet. Great! I prefer to keep EGTB support even if the improvement is negligible for TRACE. I hope YMMV. :-) > >>Often I see TRACE swindle a draw in R+PvR endgames and sometimes she swindles a >>RvB endgame for a win. > >In games against Phalanx (my favorite sparring partner), Gothmog often >gives away a half point in advantageous rook endings by allowing Phalanx >to simplify to a Philidor-type position. Phalanx apparently knows that >these positions are drawn, but Gothmog still thinks it has good winning >chances. I think this happens often enough that adding tablebase support >should give a small, but measurable improvement. These are the type of where the EGTBs do payoff. > >Of course, it would be much better to actually implement knowledge about >the third-rank defence in my evaluation function. I will probably do >so some time in the future. > I agree its best to have the knowledge built in so that the knowledge can be applied before its too late. >>But accessing the egtbs is very slow so frequently she loses because her >>NPS is severely hampered.. > >Huh? I haven't noticed any slowdown at all. When do you probe? I probe >in all positions where the last move was a capture, and the remaining depth >is at least 5 plies. I probe only after captures in all interior nodes... maybe that's my mistake. I might try limiting this to 5 plies from the frontier as you do. > >Perhaps I simply have a much faster hard disk than you, or perhaps my NPS >is so slow to begin with that the disk access doesn't matter much. It halves my nps usually... or worse. And my HD is not the latest and greatest... > >>Uri is right when he says the game is usually over before the egtbs can come to >>the rescue. > >Usually, but not always. > >>So, the main benefit for TRACE has been knowing well in advance that she will be >>checkmated in 47 moves with best play... :-) > >Yes, that is the most noticable "improvement", here too. :-) > >Tord BTW, I'm a fan of Gothmog. My preference is for knowledge-based engines like yours that cut through the tree with lots of smarts. Its beaten up TRACE on many occasions. She's slow AND stoopid, unfortunately. :-) Best wishes, Ross
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