EGTB Online distributed kbpkn.tbs stats file is incorrect

[jkominek]

This is mostly directed at Kirill, but other people will likely want to be aware of this as well. The stats file kbpkn.tbs that is distributed on Kirll's EGTB Online web page is incorrect. It's packaged in the file all-5-men-32p-tbs.zip.

I discovered this in the process of working on my revamped version of Nalimov's tbgen code (henceforth Kominek's tbgen2), wherein I found it wise to generate all 3-5 man tables as a regression test. In this one case my generated stats file disagreed with the reference. Faced with such as conflict my usual response runs along the lines of "oh bother, what have I mucked up now?" Looking again, however, my stats agree with those generated by FEG, a valuable double-check. So I dug out the precompiled tbgenm.exe that was included in Nalimov's release (*) and generated kbpkn from scratch. Two days later, the verdict: all three programs are in agreement.

This signature of the the bad stats file are dtm values over 100.

Code: Select all

 ---- from the bad kbpkn.tbs
wtm: Mate in 105:             2
wtm: Mate in 104:             2
wtm: Mate in 103:             5
wtm: Mate in 102:             5
wtm: Mate in 101:             1
wtm: Mate in 100:             2

In fact, the max dtm is 100, which is consistent with Kirill's longest checkmates page, found at http://kirr.homeunix.org/chess/longest- ... ngth.shtml.

Interestingly, the wtm lost and btm mate values are correct, but the wtm mate and btm lost values are all wrong. I can't say I know how this could have happened with such a behind-the-times 5-man file. It isn't obviously mixed up with another one.

I've attached the kbpkn.tbs file from my running of the official, as it were, tbgen program.

john

(*) Possibly compiled by Dann Corbit?

[Kirill Kryukov]

Thanks for this finding John! I will update the archive at my website.

EDIT: Web-site updated.

[jkominek]

Thanks for the quick response Kirill. In response I've updated the subject line accordingly.

john

[guyhaw]

Yes - I've known this for years, and did inform Eugene Nalimov and Rob Hyatt accordingly. I have said so on various occasions but there is no persistent outlet for the info. No idea how it got like that, or why they did not repair the problem.
The problem was revealed because two standard checks were to (a) make sure the totals for won/drawn/lost/broken added up to the index-size, and (b) make sure that those totals were the same for the DTC and DTZ metrics when those EGTs were generated.
I have got a correct set of stats for this endgame if needed.
g

[guyhaw]

Previous mention of this problem was at http://kirr.homeunix.org/chess/discussi ... ?f=6&t=746 : 2006-08-16.
g

[jkominek]

I remember that one. The thread in which a certain guy assured us that yes, "Actually, I am listening ...".

As the Chief Gatherer of endgame knowledge it is reassuring that you were on top of this error. Less so that it slipped my attention.

Robert Hyatt is no longer distributing the incorrect kbpkn.tbs file, I am happy to report (just checked his ftp site), but in an odd manner. All 3-5 .emd files are available, but with no .tbs files. In contrast, many 6-man .tbs files are available, but no .emd files. He's an odd fella by any score, so what of it?

j

[guyhaw]

Well, I'm listening when I'm visiting. But I haven't been visiting lately.
Wouldn't say I'm the Chief Gatherer of Endgame Knowledge, and certainly not of data. I don't have many of the 6-man EGTs, and I don't have the chessic insight of Marc B, John Nunn, Emil Vlasak or most of the members of the Chess Studies Community. But thanks for the idea anyway.
g