See P1338946 cooked.
paul: Compare with P0002278 & P0002279 (2010-04-30)
Mu-Tsun Tsai: This one is by far the toughest retro I've ever solved. Very little certain information can be determined by structural consideration alone, even with long and complicated argument. It took me five days to complete solving this. (2012-07-22)
A.Buchanan: @Mu-Tsun: that's an interesting data point - thanks for posting. (2017-09-07)
Henrik Juel: The current record is 58.5 moves in a proof game problem by the authors + Keym, Die Schwalbe 2017 (2017-09-07)
Henrik Juel: I just learned that the 58.5 move proof game has been cooked... (2017-09-07)
A.Buchanan: In retrospect, my earlier comment about "interesting data point" is a bit weak. It's actually great that for such an extreme problem, someone took substantial time to independently validate it. It's like doing science: people want to do their own new stuff, and are unwilling to take the time to validate what's already been claimed. This one has survived 30+ years, and maybe the use of constraints e.g. in Jacobi can eventually allow it to be HC+. (2021-05-29)
Olaf Jenkner: This problem is the current record, because P1338946 (58.5 moves) has been cooked. (2021-11-25)
Reto: This is C+ up to 51.0 moves with Stelvio 2.0. This ties the record for partial testing of an SPG. Took 1200 CPU hours of strategy seeking (finding 378 0+0 strategies) and another 13h of strategy playing these strategies. If this can ever be completely solved, then it needs to be the case that all strategies have 0+0 free moves, otherwise playing is utterly hopeless.
@Andrew: There is absolutely no way a brute-force based program like Jacobi ever stands a chance at solving something like this, no matter how many conditions you add. (2023-12-14)
Paulo Roque: obs: 24.S1c3 (2008-12-16, hidden) more ...
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Sally: Eine eindeutige BwP., die lange Zeit den Längenreord hielt und, wenn auch mit langer Verzögerung, wesentlich zum Boom dieser Gattung in den letzten 15 Jahren beigetragen hat. Im-
mer noch eine faszinierende Aufgabe. Nr. KF-13 Schwalbe Okt. 2005. (2011-12-05)
Moldenhauer: Ergänzung: Keine Lösung: BP 40.5, BP 41.0. (2023-05-20)
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Henrik Juel: Very good, Sebastian (although not for the author...) (2019-06-17)
paul: Probably the cook of the year, because the problem is well known. Which is now the length record for a capture free proof game? (2019-07-16)
paul: The length record for a capture-free PG is now 40.5 moves by Th. le Gleuher (Phenix50/1997) (2019-07-16)
Mario Richter: The problem Paul was referring to is P0006623. So far it has resisted all my and rawbats' attempts to cook it, and I think that chances are high that it is indeed correct ... (2019-07-17)
James Malcom: See the correction P1386520 (2021-02-15)
Paulo Roque: obs: 16.T1a3 (2008-12-13, hidden)
Sebastian Natschke: Cook: 1. h4 a5 2. Th3 Ta6 3. Tf3 Te6 4. g3 Te3 5. Lh3 Sh6 6. Le6 Sf5 7. Lc4 d5 8.
Kf1 Dd6 9. Kg2 Da6 10. Kh3 Kd7 11. Kg4 h5+ 12. Kg5 Th6 13. a4 Tb6 14. Ta3
Kc6 15. Tc3 Tb3 16. Sh3 Ta3 17. b3 Ta2 18. La3 Sd4 19. Lc5 Lf5 20. La7 Db6
21. Sf4 Kc5 22. Sg6 Kb4 23. Sh8 g6 24. La6 Lg7 25. Tc5 Db5 26. c4 Sc2 27.
Sc3 Ka3 28. Se4 Lc3 29. Da1 Lb4 30. Df6 Tc3 31. Kh6 Kb2 32. Kg7 Ta3 33. Kf8
Sd7+ 34. Ke8 Ka2 35. Kd8 Sa1 36. Kc8 Sf8+ 37. Kb8 Sd7+ 38. Ka8 Tc1 39. Lb8
Sb6+ 40. Ka7 Sa8 41. Db6 Tg1 42. Sf6 De8 43. Sd7 Ld3 (2019-06-17, hidden) more ...
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See P0003960
Henrik Juel: The forward part is C+ Popeye 4.61 (2022-06-01)
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Verbesserung des Rekords von Gerald Ettl (P0006424) um einen Einzelzug.
James Malcom: Is this the length record for 32 units? (2021-02-16)
A.Buchanan: Isn’t there a length record catalogue by Alain Brobecker? (2021-02-17)
A.Buchanan: http://abrobecker.free.fr/chess/lengths.pdf (2021-02-18)
James Malcom: I do not find this in there. (2021-02-18)
A.Buchanan: Yes, I see now. I had thought that Alain's paper was comprehensive for its time, but I guess not. The "Number of last moves" space is a good candidate to be put in a PDB page, like the "first move" page. That's pretty easy to do, based on the structure that Alain has given, but some scholarship is required first to validate what the last records are 10 years on, for the different cases. For example there's Thierry Le Glueher's extensions of Gyula Breyer's stupendous matrix. Those are already in PDB. Should also reach out to the Usual Suspects to ask what they've done which should be included. I don't think that Alain is active in this particular area right now. Any volunteers to own it? :) I have too much going on right now to own this, but I am happy to support e.g. by searching WinChloe, proof-reading etc. There are some magnificent problems here: this is worth doing. (2021-02-19)
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rasatom: Bh1 is promoted. (2022-05-25)
Erich Bartel: weiterer Nachdruck:
4) Minitehtäviä 1990 (2011-03-27, hidden)
Alfred Pfeiffer: Urdruck: 69 "feenschach" 39, 07-10/1977, S.123 (2012-02-20, hidden) more ...
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Anton Baumann: C+ Alybadix (2022-07-13, hidden) more ...
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HBae: Dual ... 6.Te2 Kg4 sy. Symmetrieachse = h1-a8. [HB]
siehe BuB zu JS und PK (2023-01-19)
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HBae: NL (Kurzlösung) 1.Kh6 2.Kh5 3.Tg2 4.Tf2 5.Le5 6.Lg3 Kd1 sy. Symmetrieachse = h1-a8. [HBae]
siehe BuB zu JS und PK (2023-01-19)
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HBae: NLs b) 1.Lf1 2.Kh3 7.g8=S 8.Se7 9.Sc6 Kb7 sy. Symmetrieachse = h1-a8.
1.Kh3 2.Lc8 7.g8=D 8.Dg1 9.La6 Kb8 sy. Punktsymmetrie Brettmitte. [HB]
siehe BuB zu JS und PK (2023-01-19)
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Anton Baumann: C+ Alybadix (2022-01-25, hidden) more ...
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HBae: NL (Kurzlösung) 1.Kb7 7.Kg1 Kb4 sy. Symmetrieachse = Mittelsenkrechte. [HB]
siehe BuB zu JS und PK (2023-01-19)
Alfred Pfeiffer: Diagrammfehler? 9.Kc1 geht nicht und ist auch keine SY. (2012-07-21, hidden)
Erich Bartel: aj, mein Eingabefehler. Fanke für den Hinweis, habe korrigiert. (2012-07-21, hidden) more ...
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Anton Baumann: Forderungsänderung bei P1363253; bis auf die letzten Züge ist die Lösung identisch.
C+ Alybadix (2022-03-28)
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HBae: NL a) 1.Lf7 2.Sd6 3.Kc4 4.Kd5 5.Ke6 Kc7 sy. Symmetrieachse = Mittelsenkrechte.
siehe BuB zu JS und PK (2023-01-19)
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HBae: NL (Kurzlösung) 1.Kc5 2.Kd4 3.b6 4.b7 Kg2 sy. [HB]
siehe BuB zu JS und PK (2023-01-19)
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HBae: NL (Kurzlösung) 1.Ka2 2.Kb3 Ke6 sy. [HB]
siehe BuB zu JS und PK (2023-01-19)
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Anton Baumann: C+ Alybadix (2021-12-31)
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Anton Baumann: C+ Alybadix (2023-03-13)
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SCHRECKE: C+ (auch Satz), popeye 4.87 (2022-03-27)
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James Malcom: Since P1375224 and P1297870 are both cooked, I did a search of PDB and this was the longest correct checking, and logest string of checks, that I found. I’ve keyed it as such for now. There is but a minor dual here. (2020-09-01)
James Malcom: The record is now 47: P1402132 (2023-06-16)
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James Malcom: I believe that this is the record for the longest Kindergarden problem! The second longest that I know of is P1299269. (2020-02-14)
James Malcom: Actually, as it turns out, this is superseded by P1382048, with a total of four whole moves. (2020-11-18)
James Malcom: I believe that this is the record for the longest Kindergarten problem! The second longest that I know of is P1299269. (2020-02-14, hidden) more ...
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A.Buchanan: Any kind of assessment of soundness of this one? (2020-11-19)
James Malcom: Andrew, there is no doubt about the soundness. Sure, the ending may have a few duals, but those are generally acceptable in Blathy's correct work. Here is the proof.

All White pawns are immobile. The kingside mustn't move, or else Black breaks through and wins. Nor can a7, b2, or b6 without losing the winning chance.

The Black king is stuck, of course. The Black kindgside pawns are forever held up by White's, and the queenside ones can't move, or else Black would soon be in zugzwang and lose.

Lastly, the White king can't go after the Black pawn to shorten the game, or the Black queenside pawns must be tended to. If the White king reaches either e5 or f4, then Black plays b4!, threatening to queen soon. So the White king must hurry back, Black gets the White queen stuck as well, and it is a draw.

With a restricted White king to the given triangulation corridor, the Black king stuck, all pawns pawns frozen on their journeyes, the soundness is guranteed. (2020-11-19)
James Malcom: Furthermore, on move 99 with Black to move, chess.com analysis agrees with checkmate in move 112, albeit with a few move order corrections that I've just made. So it is still correct, with a Blathy style taste in duals. (2020-11-19)
Anton Baumann: Nach 99. - b4 gemäss Gustav noch 12 Züge; das ist #111.
Korrektur: ... 108.De4 Kc8 109.c6 Kd8 110.Kxb5 111.De8# (2020-11-20)
James Malcom: Fixed. (2021-01-20)
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James Malcom: Does anyone have any idea why the animation does not work? (2022-03-03)
James Malcom: Thanks for fixing it Mario. (2022-03-04)
A.Buchanan: The animation now rejects any ambiguous move (e.g. Dc7 rather than Dcc7) rather than silently guessing. A good improvement! (2022-03-04)
Mario Richter: The problem here was White's 38. move. There are two Queens that could reach b7 from the a-file, and two Queens, that could reach b7 from the 8th rank. So to make the move unambiguous, James correctly wrote it as Da8b7. Unfortunately, at the moment the PDB-System cannot handle this very special case. As long as this bug is not corrected in the PDB-Software, as a fix one can use long algebraic notation for "problematic" moves. (2022-03-04)
A.Buchanan: @Mario: I'd never thought about what the notation would be for this corner case! You are correct: https://www.chessprogramming.org/Algebraic_Chess_Notation#SAN Ambiguities case 3. I guess this can be earliest encountered with queens or knights at W11, or with bishops at W12 (2022-03-05)
A.Buchanan: Oops: knight is W10. So obv q, can this be done with proof games? (2022-03-05)
A.Buchanan: See P1399677. (2022-03-07)
A.Buchanan: @Mario: I'd never thought about what the notation would be for this corner case! You are correct: https://www.chessprogramming.org/Algebraic_Chess_Notation#SAN Ambiguities case 3.
Note that this problem is also Belfort :) (2022-03-05, hidden) more ...
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