Size of 7-man EGTB with pawns only? With at least one pawn?

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Size of 7-man EGTB with pawns only? With at least one pawn?

Postby MarkS » Tue Sep 01, 2009 4:01 pm

I'm thinking of trying to get a collection of the 6-man tablebases, and from reading these forums I guess that will take between 1 and 1.5 TB.

And it got me thinking about the 7-man tablebases... I'm not into engine-engine competitions, just playing through games and getting engine analysis - so I figure the most useful 7-man information will be those positions that contain at the very least one pawn on the board (human games rarely have 7 pieces left with no pawns). Now I think I've read that the 7-manners will take about 1000 TB or so (please correct me).

About how much memory is required for 2 Kings and 5 Pawns?

About how much memory is required for 2 Kings and all the positions with 1-4 pawns (and the appropriate number of other pieces to bring the total to 7)?

About how much memory is required for 2 Kings and 0 Pawns (meaning of course, 5 pieces on the board)?

I'm not looking for any definitive number, just a ballpark guess from you guys that think about this stuff all the time.

Mark
Michigan, USA
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Re: Size of 7-man EGTB with pawns only? With at least one pawn?

Postby Codeman » Wed Sep 02, 2009 8:49 am

First of all, note that for every pawnfull endgame you also need to have the files for at least one of the pawns changed to N, B, R, Q. Otherwise you are risking that the engine doesn't know how to continue after promoting. Thats also the reason why once the 7 men should be generated we have to start with the pawnless endgames.

About how much memory is required for 2 Kings and 5 Pawns?


number of entries: 1806 (=number of arrangements of the 2 kings with pawns on the board considering that the board can be flipped and kings can't stand next to each other) * 48 * 47 * 46 * 45 * 44 = 371090522880
furthermore you can take advantage of the fact that the pawns are interchangeable. So for example the endgame KPPPKPP 371090522880 / (3! * 2!) = 30924210240

Now you can choose what data you want to store .. in case of Nalimov's DTM you can get about 2 entries / byte after compression (taken from the KPPKPP endgame) so this would leave you with about 14 GB memory requirements.

This should give you a raw estimate. The other figures you can calculate in the same way just for non pawns you have to multiply by 62 * 61 * 60 ... and for the pieces only endgame the two kings only require 462 entries. Also note that the compression ratio may vary for different endgame types.

regards,
Edmund
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Re: Size of 7-man EGTB with pawns only? With at least one pawn?

Postby kronsteen » Wed Sep 02, 2009 12:58 pm

Some considerations first :

- 7-men won’t be available in the near-term future. Several years will be needed.
- Final size depends of metrics used a lot. Current 6-men TBs (1,2 Terabytes) are in distance-to-mate (DTM) format, which is the most expensive in space storage. Current estimates for a full set of 7-men in DTM format are in the 150-200 TB range (not 1000 TB). But this is long term view, first built 7-men TBs might well be in more compact formats such as distance-to-zeroing-move (DTZ, full set ~ 60 TB) or win-draw-lose tables (WDL, full set ~15 TB).

MarkS wrote:About how much memory is required for 2 Kings and 5 Pawns?


3 pawns vs 2 (kpppkpp) alone might be approximately 25-30 GB (in DTM format, much less in DTZ or WDL). 4 pawns vs 1 (kppppkp) might be 10-15 GB. But beware of the incomplete tablebase problem as quoted by codeman above. Note also that construction of these TBs requires construction of all other TBs first, and shall not be available soon.

MarkS wrote:About how much memory is required for 2 Kings and all the positions with 1-4 pawns (and the appropriate number of other pieces to bring the total to 7)?

About how much memory is required for 2 Kings and 0 Pawns (meaning of course, 5 pieces on the board)?


One can expect (ballpark guess as you say, give or take 50% at least) :

For all 7-men with pawns (including 4 vs 3 and 5 vs 2, but not 6 vs 1) : 140 TB in DTM, 40 TB in DTZ, 12 TB in WDL. For all 7-men without pawns : 40 TB in DTM, 20 TB in DTZ, 3 TB in WDL.
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