Author: Andrew Dados
Date: 23:46:15 04/02/00
Go up one level in this thread
On April 02, 2000 at 22:39:06, Tina Long wrote: >On April 02, 2000 at 11:03:56, Robert Hyatt wrote: > >>On April 01, 2000 at 23:17:11, Tina Long wrote: >> >>>Hi guys, >>>This thread has been interesting & generally agreed with previous stuff I'd >>>read. >>> >>>So. >>>Analysing 3 best moves, over 24hours, slows the program by a factor of 3 - 6, >>>losing 1 or 2 ply depth. >>> >>>Each extra Ply has a 15% of picking a different move, that the software >>>calculates is better. >>> >>>But. >>>What about the Actual ply depths searched on the 2nd & 3rd preffered moves? >>>If only the best move is shown, no's 2 & 3 share with no's 4... about 50% of the >>>search time. >>> >>>If best three is shown, no's 2 & 3 are receiving 6 - 10 X more thinking time. >>>1st preferred move has gone from 50% to 25% of thinking time (25% for "rest") >>>or 1st preferred move has gone from 50% to 17% of thinking time (50% for "rest") >>> >>>preferences 2 & 3 are being searched an extra 1 - 2 - 3 ply deeper over 24hrs. >>>Their "score" is more acurate than if only 1 best is shown. >> >>I don't follow "being searched an extra ply and their score is more accurate >>than if ..." > >By looking at 3-best instead of 1-best, the 2nd & 3rd best moves are examined >about 6 X longer in time. In 24 hours they are searched for about 4 hours each, >instead of about 40 minutes each. All I'm saying is that there must be more >accuracy in the "score" for those moves. If the 6X time doesn't result in an >extra ply or 2 of depth, then the actual amount of computing at the reached >depth must achieve something, or else be redundant. > >> >>Here is the main point: If the best move looks best thru 19 plies, but is >>going to look horrible at depth 20, the 3-best display may ensure that you >>only get to 19, where you would get to 20 normally. So the normal search >>will see that the best move is horrible and find an alternative if one is >>available. The 3-best search will only get to depth 19 and think that the >>original best move is the one to play. > >Granted, something may be missed by not moving from the 19th to 20th ply. But >how much is being missed in the examination of 2nd & 3rd best moves when only >1st best is shown. > >I am suggesting that "If the "score" of the best 3 moves is not too dissimilar" >increasing the analysis time from about 40min to 4 hours for 2nd & 3rd best May >find one of them to be actually Best. This is the Benefit to weigh against the >Cost of the 1st best move being analysed to 19 ply rather than 20 ply. > >> >> >>> >>>So. >>>If the "score" of the best 3 moves is not too dissimilar, then "forcing" the >>>program to look at choices 2 & 3 for longer could be a good thing. >>> >>>Eg. >>>guessed ply depths "well" searched for the first four choices over 24 hrs. >>> >>>Show 1 best: 1-19 2-15 3-15 4-15 >>>Show 3 best: 1-17 2-17 3-17 4-13 >>> >>>Is the "danger" of reducing the favoured move ply from 19 to 17 greater than the >>>"benefit" of increasing the 2nd & 3rd ply from 15 to 17? >> >>I don't follow how the second/third moves are increased. They are _all_ >>searched to the same depth each iteration, even in normal mode where only the >>best move and score is displayed. But _all_ moves are searched to this depth. >> >When only the best move is displayed, 50% of the time is spent examining that >best move. All other moves share the other 50% of time. If they are all >examined to the same ply depth, then many more "somethings" must be being >examined in the best move compared to the 2nd best move. > >Is there any benefit in examining more "somethings" (for 6X the amount of time) >in the 2nd & 3rd best move, at the cost of an extra ply for the best & all other >moves. > >I realise I'm not being clear, but all that extra time being spent on 2nd & 3rd >best, must be doing something for the accuracy of their analysis. > >Thanks >Tina Long > > > > >>>Tina Long This extra time is not spent in going deeper, but in calculating an exact score and PV for second/third move. So it is 'wasted' for 'normal search'. 'Normally' only one (best) move gets accurate score. And it will have a PV. Calculating that exact score and PV takes up to 50 % of time for each ply, yes. All other moves are not getting a correct score - it's enough if I prove they are worse then 'best move'. If you want an exact score, then program will waste time to calculate that. I am not sure this post clears things up, but anyway - I tried..:) -Andrew-
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