Author: Marcus Heidkamp
Date: 00:56:24 06/06/01
Go up one level in this thread
On June 06, 2001 at 03:05:54, Guido wrote: >IMHO in the last question you are right: it is possible to use one only >tablebase (.nbw or .nbb) to find the response for an ending position. I did it >with my tablebases, not with EGTB, seemingly with success, but the program >becames very complicated and cpu time increases consequently, so I abandon the >idea. > >In fact, suppose you use a .nbw file, there are four possible situation: > >1) you can use the .nbw tablebase directly >2) after exchange of the men colour you can use the .nbw tablebase directly >3) you have to make a ply and after you can use the .nbw tablebase >4) you have to make a ply and exchange the men colour and then you can use the >.nbw tablebase > >But in the two last cases you have to analize all the possible plies to find the >best result, but what happens if the ply is a promotion or a capture? Obviously >you have to load another tablebase and repeat the procedure; moreover the >loaded tablebase could not be used directly, but it could need an exchange of >men colour or, in the worst case, the execution of another ply or both. And this >process could continue so the code must be recursive. >During this process you have to save the best result for the player, keeping >into account every time you need of a ply or of an exchange of colour. Very >simple :-)! > >So my opinion is that the game is not worth the candle (italian: il gioco non >vale la candela) > >Ciao >Guido Antonelli Actually I use the TB probing code just after my Hash probe, and a successful TB probe will be stored permanently (i.e. with a maximum search depth) to the hash table. I did not see any significant performance deficits, but my program is still a rough sketch. I guess, because I use MTD(f) as the Alpha-Beta-Driver, it works due to the cutoff-approach of MTD. Regarding your four points I think that going one ply deeper is not a real problem. If you do captures or promotions you have to look into the new TB anyway. Of course you have to do on average the av. branching factor/2 (i.e. 38/2=19). But for people lacking disk space (like me) it works, instead of giving no result at all, or doing the 1-ply search manually. And for the professionals: If the other side exists, you simply cut off and do not search one ply deeper. So what's the disadvantage there? Marcus
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.