Is there now coming changes to syzygy databases?

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Jouni
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Is there now coming changes to syzygy databases?

Post by Jouni » Mon Nov 13, 2017 10:09 am

And which kind? Smaller size, DTM and/or 7 piece?
Jouni

phhnguyen
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Re: Is there now coming changes to syzygy databases?

Post by phhnguyen » Tue Nov 14, 2017 1:55 am

Jouni wrote:And which kind? Smaller size, DTM and/or 7 piece?
Just curious: why you think syzygy will or should suppose DTM?

I have been using DTM in my EGTs since they has been developed for a while but I am not clear about reasons to change back from syzygy's DTZ50 to DTM.

Jouni
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Re: Is there now coming changes to syzygy databases?

Post by Jouni » Tue Nov 14, 2017 7:43 am

I have seen a lot of discussion in TCEC chat (I am not joined myself).
Jouni

syzygy
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Re: Is there now coming changes to syzygy databases?

Post by syzygy » Tue Nov 14, 2017 7:52 am

I have adapted my generator for DTM, but DTM tables cannot replace WDL/DTZ. But they can be used in addition to WDL/DTZ to get mate distances (huge waste of disk space, though).

I am not yet finished.

Michel
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Re: Is there now coming changes to syzygy databases?

Post by Michel » Tue Nov 14, 2017 9:06 am

I have adapted my generator for DTM, but DTM tables cannot replace WDL/DTZ. But they can be used in addition to WDL/DTZ to get mate distances (huge waste of disk space, though).
That is really good news!! I expect Texel will put these TBs to good use!
Ideas=science. Simplification=engineering.
Without ideas there is nothing to simplify.

phhnguyen
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Re: Is there now coming changes to syzygy databases?

Post by phhnguyen » Tue Nov 14, 2017 10:03 am

Jouni wrote:I have seen a lot of discussion in TCEC chat (I am not joined myself).
Silly question: what’s TCEC chat? Can you give me the link of the main discussions?

So far I have found only a serious discussion in Rybka forum.
Many thanks

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Nordlandia
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Re: Is there now coming changes to syzygy databases?

Post by Nordlandia » Tue Nov 14, 2017 1:28 pm

Nguyen Pham link please :)

jwes
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Re: Is there now coming changes to syzygy databases?

Post by jwes » Tue Nov 14, 2017 10:53 pm

syzygy wrote:I have adapted my generator for DTM, but DTM tables cannot replace WDL/DTZ. But they can be used in addition to WDL/DTZ to get mate distances (huge waste of disk space, though).

I am not yet finished.
Would it be possible to replace some DTZ tables with DTM if those tables have no cursed wins or blessed losses?

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Re: Is there now coming changes to syzygy databases?

Post by syzygy » Tue Nov 14, 2017 11:13 pm

jwes wrote:
syzygy wrote:I have adapted my generator for DTM, but DTM tables cannot replace WDL/DTZ. But they can be used in addition to WDL/DTZ to get mate distances (huge waste of disk space, though).

I am not yet finished.
Would it be possible to replace some DTZ tables with DTM if those tables have no cursed wins or blessed losses?
It would not be a perfect replacement.

Suppose the engine is on the losing side in KQvKR. The opponent can always win it within the 50-move rule, but he might play several suboptimal moves that bring the 50-move counter to, say, 25 moves with 26 moves remaining until the capture of the rook. So now the engine has a "blessed loss" within its reach, but without DTZ table it might not be able to tell and it might not play the right moves. (DTM would try to postpone the mate as much as possible, possibly at the cost of losing the rook a move or so earlier.)

Anyway, current Cfish is able to deal at the root with any of WDL+DTZ, WDL+DTM and WDL+DTZ+DTM.

In the search, Cfish will probe WDL at TB positions and then only probe DTM if the normal TB-win score is does not lead to a cutoff (i.e. if a win is already certain and the engine starts to look for the shortest win). This fits nicely with the early_mate approach. It is also possible to use 6-piece WDL(+DTZ) with 5-piece DTM.

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Re: Is there now coming changes to syzygy databases?

Post by jwes » Wed Nov 15, 2017 12:53 am

Is WDL+DTZ+DTM enough to ensure perfect play under the 50 move rule or do we need DTM50?

Another idea you may already be doing is splitting tables where one side has two bishops into two parts, one with one bishop of each color and one with both bishops on the same color. This would likely improve compression and would improve caching.

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