Author: Uri Blass
Date: 06:36:24 01/31/02
Go up one level in this thread
On January 31, 2002 at 08:50:35, Albert Silver wrote: >On January 31, 2002 at 08:33:12, Uri Blass wrote: > >>On January 31, 2002 at 07:51:19, Albert Silver wrote: >> >>>On January 30, 2002 at 23:28:50, Robert Hyatt wrote: >>> >>>>On January 30, 2002 at 11:52:45, Albert Silver wrote: >>>> >>>>>On January 29, 2002 at 23:53:06, Robert Hyatt wrote: >>>>> >>>>>>On January 29, 2002 at 06:40:12, Albert Silver wrote: >>>>>> >>>>>>>On January 29, 2002 at 04:31:39, Jeroen van Dorp wrote: >>>>>>> >>>>>>>>Convecta claims to ave them (complete) on 9 CD's. Are there still some missing >>>>>>>>or so? >>>>>>>> >>>>>>>> >>>>>>>>http://store.convekta.com/shop_model.asp?gid=121&sView=Catalog >>>>>>>> >>>>>>>>J. >>>>>>> >>>>>>>A few piece combinations were indeed removed as they took up space for no good >>>>>>>reason. The combinations in question are King + 3 queens against King, King + 2 >>>>>>>queens + rook against King, etc. They represent no practical value to either the >>>>>>>user or the engine and removing them saves from 1-2 Gb of HD space. >>>>>>> >>>>>> >>>>>> >>>>>>They do have _some_ merit. If the engine probes after a capture takes it to >>>>>>5 or less pieces, then you want to get a hit. If you omit some tables, some >>>>>>of the probes will fail, wasting time. And causing extra search. >>>>> >>>>>I don't understand. If the search at that point doesn't get a tablebase hit with >>>>>a KQQQ vs. K and instead gets a score of +30 pawns, it will somehow contrive to >>>>>play worse?? Or make a poorer choice? Say opt for an alternate line that gives >>>>>it +35 pawns instead of the direct mate? >>>>> >>>> >>>> >>>>First, that screws up the alpha/beta search. If _all_ the scores are near a >>>>mate score, and then a few drop way down, that widens the search window and >>>>makes the search go slower. If you are already winning, fine. But if you >>>>are not, this can hurt. >>> >>>Remember that the ONLY missing tables are those lopsided ones with 3 queens to >>>none, etc. Minor pieces are all there though, as well as ones that have genuine >>>drawing chances, however slim. If ALL the scores are near mate, and the only >>>ones that aren't are those missing tables (with the +30 scores), it's pretty >>>safe to assume you are already winning IMO. >>> >>>> >>>>Also you can look silly... would you _really_ want to hit a KNN vs KP ending >>>>and possibly draw, because the tables say MATE in N, rather than hitting a >>>>KQQQ vs K which says +30 rather than mate in 9 or whatever? >>> >>>If the tables say Mate in N, then how would it draw? >> >>50 move rule but it is easy to avoid these draws by translating scores of long >>mates to smaller number and mate in 70 may be transalted to +2 so you are going >>to prefer the +30 of KQQQ vs K and not the +2. > >If the Mate in N cannot be played to mate because of the 50 move rule then the >program should _never_ prefer it to a score over 0.00. In which case it is >definitely preferrable to choose the +30 score. Telling the program that its >Mate in N is equal to +2 isn't an improvement IMO. > >That does bring up a question though regarding the laws of chess, which I think >I will submit to FIDE. The question is this: I know (unless the rule changed) >that if a player announces a definite mate in N before the time control though >he doesn't make the time control, the mate, if confirmed, is what stands and not >the clock. I did not know it. Does it mean that a human who does not know how to win KQ vs KR endgame(or at least is not sure that he knows) may claim mate in at most 40 and later prove it by a computer program. I think that it is illegal and I remember a case in the world championship when KQ vs KR was drawn. I know that if the position is mate for one side then the position is important and not the clock but I believe that if there is mate in 5 I cannot stop the clock and say mate in 5 and I never saw players do it. players can say mate in 5 but the game should continue. There was one case that I said mate in 10(or another number of moves) when I was the operator of Rebel in the israeli league and somebody told me that it is not polite to say mate. I did not stop the clock and I did not think that I have the right to stop the clock and say that Rebel won the game. Uri
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