BrainKing - Diskussionsborde (Chess variants (10x8))

Chess variants (10x8)

Sam has closed his piano and gone to bed ... now we can talk about the real stuff of life ... love, liberty and games such as
Janus, Capablanca Random, Embassy Chess & the odd mention of other 10x8 variants is welcome too

For posting:
- invitations to games (you can also use the New Game menu or for particular games: Janus; Capablanca Random; or Embassy)
- information about upcoming tournaments
- disussion of games (please limit this to completed games or discussion on how a game has arrived at a certain position
... speculation on who has an advantage or the benefits of potential moves is not permitted while that particular game is in progress)
- links to interesting related sites (non-promotional)

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21. September 2006, 21:23:42

ChessCarpenter

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Emne: TableBases

This post is just for informational purposes only, and doesn't apply to any one person, program, or game. I think most of us are aware that the 6-piece tablebases for 8x8 chess are completed. This was a massive undertaking, and a DISTRIBUTED project that covered many years, and many computers being used in parallel to complete the task. As for 10x8 chess variants, only the 5-piece tablebases are completed. Just so everyone knows, the branching factor for 10x8 board with the 2 new pieces is just gigantic when compared to 8x8 chess. For example, the 4-piece tablebase set for 10x8 with the Chancellor and Archbishop takes only 26 minutes to compute. The 5-piece set required 34 days! The ratio of time involved was more than a factor of 1800! Also remember the longest 5-piece 10x8 win is 268 moves (not plies) which is longer than the longest 6-piece tablebase win (262 moves) for 8x8 chess.

The 6-piece tablebase set has not even been started, nor does it make sense to begin. The time scaling for its completion will be roughly 75 (number of squares on which to place piece #6) x 2 (each "distance to win" must reserve 2 bytes whereas the 5-piece set only needed 1) x 343 (this times as many more tablebase slices to solve) = over 50,000 times as long as the 5-piece set. These numbers are mind boggling. The 60 gigabyte 10x8 tablebases are all that exist. There is no "1 terbayte" set anywhere. The average tablebase file for the 6-piece set will be 75 x 2 = 150 times the size of the 5-piece files. So, they will be about 300 GB each. This mysterious "1 terabyte" that was mentioned before would only be the size of 3 files, if they were completed (and they are not.) Everyone is probably aware that you have to solve the non-pawn files first, such as King + 2 Queens vs. King + 2 Queens, King + 2 Queens vs. King + 1 Queen + 1 Chancellor, King + 2 Queens vs. King + 1 Queen + 1 Archbishop, etc. Even if these tablebase files were completed, totalling about 1 TB, they would be statistically of no help whatsoever during the coarse of a game between 2 programs.