Author: Albert Silver
Date: 05:50:35 01/31/02
Go up one level in this thread
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 wonder how an announced mate would affect the 50-move rule. For the
moment it can't AFAIK, and of course FIDE never expected to have to deal with an
announced mate going beyond the 50-move rule, still it is worth mentioning. They
may not allow computers in FIDE events theoretically, but the condition could
theoretically happen with a human (such as from those guys who memorize phone
books) so what then?
Albert
>
>Uri
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