7-men Syzygy attempt

[Sesse]

I have looked recently at merging the CFish version of tbprobe.c into my fork of Fathom, but there a lot of diffs, so that it is kind of a tall order. And I don't have 7-man bases to test it with.

Yes, that's what I noticed, too…

Pull requests are welcome, though.

Does this hold in general? I'd love to get in the patch in https://github.com/basil00/Fathom/issues/22.

[jdart]

Does this hold in general?

Sure, you can submit it. I don't use this feature (move_to_str) myself - so I was not aware there was a bug there.

--Jon

[Ozymandias]

WDL for N pieces requires WDL for (N-1) pieces and below.

Got it, thanks.

What is not needed for WDL are the tables that can be reached through promotions.

So if you are only interested in KRPPvKRP and only need WDL, then you must download just KRPPvKRP and all 6-piece WDL TBs (or at least those that can be reached through captures, but you're not going to gain much by being selective with 6-piece tables if you are downloading the much bigger 7-piece tables). You don't need all KRXYvKRZ if you are only interested in adjudicating KRPPvKRP positions or in analysing positions for which KRPPvKRP is important.

(But if you want to play out KRPPvKRP positions to mate reliably, you need all the tables that can be reached through promotion and the corresponding DTZ tables.)

The total size of 6 men WDL is less than 1% the size of 7 men WDL, so cherrypicking those tables is rather excessive. Nonetheless, the explanation helps better understanding the inner workings of syzygy.