Author: Uri Blass
Date: 08:12:50 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. > >>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. > >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. > >>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. > >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. > >>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 It may be a disadvantage because the program may prefer to get endgame with no practical chances and not mate in 47 against itself when the opponent may blunder. I think that it is better to translate the long mate against itself to some material advantage so the program is not going to prefer to go to position with score of -12 pawns that is not tablebases position that means no practical chance. Uri
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