Die Schwalbe

40 problem(s) found in 2790 milliseconds (displaying 40 problem(s)). [COMMENTDATE>=20200919 AND G='Retro' AND K='Aristokrat'] [download as LaTeX]

1 - P0000136
Dmitri W. Pronkin
Andrey Frolkin

6631v Die Schwalbe 117 06/1989
Preis
P0000136
(14+14)
BP in 57.5
1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 5. h4 d5 6. h5 d4 7. h6 d3 8. h7 dxc2 9. d4 a5 10. Lh6 c1=T 11. e4 Tc5 12. Se2 Th5 13. e5 c5 14. e6 Sc6 15. b8=T a4 16. Tb4 a3 17. Ta4 c4 18. b4 c3 19. b5 c2 20. b6 c1=T 21. b7 Tc4 22. b8=T Da5+ 23. Tbb4 Lb7 24. S1c3 0-0-0 25. exf7 e5 26. Tc1 Lc5 27. f8=T a2 28. Tf3 a1=T 29. Sa2 g1=T 30. Tfa3 Tg6 31. f4 Te6 32. f5 g5 33. f6 g4 34. f7 g3 35. f8=T g2 36. Tf5 g1=T 37. Lf8 Tg7 38. Sg3 e4 39. Ld3 e3 40. 0-0 e2 41. Tcc3 e1=T 42. Lc2 T1e3 43. d5 Tdd7 44. d6 Tdf7 45. d7+ Kb8 46. Dd6+ Ka8 47. Dc7 Sge7 48. d8=T+ Sc8 49. Tdd3 Thg8 50. h8=T Tae1 51. Th6 T1e2 52. T1f2 Tce4 53. Kf1 Ld4 54. Tfc5 Se5 55. Sf5 Sc4 56. Sd6 Sb2 57. Tbc4 Sb6 58. Db8+
play all play one stop play next play all
Der absolute KBP-Längenrekord.
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)
more ...
comment
Keywords: Unique Proof Game, Move Length Record, Non-standard material (TTTTTTtttttt), Castling, Aristocrat, Superseded by (P1397486)
Genre: Retro
FEN: kQ3Br1/1b3rr1/1n1Nr2R/q1R4r/R1Rbr3/R1RRr3/NnB1rR2/5K2
Reprints: 584 Ukrainisches Album 1986-1990
86 Shortest Proof Games 11/1991
(6) diagrammes 103 10-12/1992
H18 FIDE Album 1989-1991 1997
feenschach 137, p. 368, 08-09/2000
Input: Gerd Wilts, 1995-06-03
Last update: James Malcom, 2021-12-25 more...
2 - P0000763
Lothar Finzer
1159 Die Schwalbe 24 12/1973
P0000763
(12+12) C+
#3
Schwarz hat keinen letzten Zug, daher beginnt er (und setzt in 3 Zügen matt):
1. ... T3d2+ 2. Lexd2 Txd2+ 3. Lxd2 Ta1#,Db3#; 3. Lb2 Txb2#,Db3#; 3. Kb1 Txc1#
Verführung: 1. Ta5+? Kxb4 2. Sc6+ Kc4 3. Tc5#
play all play one stop play next play all
Die Umwandlung aller 16 Bauern in schwarzfeldrige Läufer bzw. in Türme erforderte alle 8 Schlagfälle, und zwar so, daß alle Umwandlungsfiguren auf schwarzen Feldern entstanden. Deshalb kann zuletzt auch keine schwarze UW erfolgt sein.
Joaquim Crusats: Can anyone explain the intention? (2013-01-06)
Henrik Juel: The eight white pawns captured the four missing black officers and promoted on b8, d8, f8, and h8; the eight black pawns captured the four missing white officers and promoted on a1, c1, e1, and g1.
If White had the move, 1.Ta5+? Kxb4 2.Sc6+ Kc4 3.Tc5 would mate in three.
But Black has no last move, so he has the move and mates in three by 1... T3d2+ 2.Lexd2 Txd2+ 3.Kb1 Txc1# (2013-01-06)
A.Buchanan: This is one of a number of problems which had been given both "No legal last move for..." & "Whose move?" keywords. These should correspond respectively to two situations: (1) Codex Article 15 where we add or remove a single move from the beginning of the solutions, but the mating party remains the same. (2) A kind of one-sided duplex, where who moved last implies who delivers the mate (or other final move).
So at most one of the two keyword forms can ever logically apply to a problem. Therefore I have removed the incorrect "No legal last move for Black" keyword.
We might replace "Whose move?" by "Halfduplex", which is related to the Popeye option. What do you think? (2023-11-28)
A.Buchanan: This is a nice problem. There are some final move duals for the actual solution, but all missing units are needed to justify promotions (2023-11-28)
Henrik Juel: Halfduplex is a bit too technical for my taste, although it describes the goings on well (2023-11-28)
A.Buchanan: Thanks Henrik - I'll leave the term "Whose move?" as it is then. (2023-11-28)
more ...
comment
Keywords: Non-standard material (LLLLLLLLtttttttt), Whose move?, Aristocrat
Genre: Retro, 3#
Computer test: HC+ Popeye v4.87 (subject to final move duals) with simple retro logic
FEN: 8/N7/8/2R1B1B1/kB1BrBrB/2qrrrrr/K7/2BrBrBr
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2023-11-28 more...
3 - P0002471
Gerd Rinder
(G) Die Schwalbe 48 12/1977
Lob
P0002471
(4+3)
#2 (AP)
BTM: 1. ... Lxb7+ 2. Ke3 0-0-0 3. Sb6#
WTM: 1. Sf6+! Kd8,Kf8 2. Dc7#,Ld6#
play all play one stop play next play all
If WTM, b000 rights are already lost. Under Keym AP, Black attempts to steal the move. White disruption of castling now counts as win for White, so the only chance is 1. … BxQb7+ 2. Ke3! thr 3. Sf6+ disrupting castling but 2. … 0-0-0 3. Sb6#. 2. Kd3,Kf5? Be4+ 3. ~ 0-0-0! as b7 is no longer occupied, or 2. Kd3,Kd4,Kd5? 0-0-0! pinning wS or 2. Ke5,Kf4? 0-0-0! as wL is blocked. As usual when flip of player to move in d#n, Black gets an extra move rather than White losing one (c.f. Codex Article 15). Sublime miniature!
VL: AP after Keym. Solution:
I: 1.Sf6+.
II: Bl's try to be on move. 0... Bxb7+! 1.Ke3! O-O-O (legalizing!) 2.Sb6#. (2007-01-26)
more ...
comment
Keywords: Castling (sg), a posteriori (AP) (Type Keym), Homebase (s), Aristocrat, Miniature
Genre: Retro, 2#
FEN: r1b1k3/1Q1N4/8/8/4K3/8/7B/8
Reprints: Die Schwalbe 99 06/1986
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2023-07-21 more...
4 - P0002665
Bernd Schwarzkopf
120v feenschach 2 03/1971
P0002665
(1+1)
a) Diagramm
b) wKh8, sLa7
Ergänze zu einem IC!
a) sK, 2 sTT, 3 sBB
b) sK, 2 sTT, 4 sBB
a) sKg8, sTg7,f8, sBf7,g6,h6
b) sKc8 sTb7,d8, sBa6,b6,c7,d7
play all play one stop play next play all
Henrik Juel: In part b) the set of added men should be changed to sK, 2 sTT, 4 sBB
Both parts rely on the last move being a black castling with check (2021-10-31)
comment
Keywords: Illegal cluster, Castling (sksg), Aristocrat, Miniature, Aristocrat, Miniature
Genre: Retro
FEN: K7/7b/8/8/8/8/8/8
Input: Gerd Wilts, 1995-06-03
Last update: Mario Richter, 2021-11-01 more...
5 - P0002735
Theodor Steudel
3511 Problemkiste 95 10/1994
P0002735
(1+1) C+
(-1w -1s)*, dann h=1
2 Lösungen
R: 1. Kh2-g1 Kg4xDf3, dann 1. Kh4 Df5=
R: 1. Kf1-g1 Kg3xDf3, dann 1. Kh2 Kf2=
"set play" ( -s, dann h=1 )
R: 1. Ke2xDf3, dann 1. Ke1 Dd3=
play all play one stop play next play all

Duplicate Diagram: P1187070

Adrian Storisteanu: Is the star "*" in the stipulation supposed to indicate a kind of "set play" in the retro part -- in effect a "-1s dann h=1"? Because there is one:
- 1.Ke2xQf3 & 1.Ke2-e1 Qf3-d3=. (2015-08-02)
A.Buchanan: That's a clever interpretation Adrian, I am sure you are right, and it's sound according to Deadpos (2024-01-13)
Adrian Storisteanu: A more precise stipulation would be something like: (-w -s)*, dann h=1 (2024-01-14)
A.Buchanan: Good idea. The convention is that * promises at least one set play instance. (2024-01-15)
comment
Keywords: Help retractor, only Kings, Aristocrat, Miniature
Genre: Retro, Fairies
Computer test: C+ Deadpos v2.3 14-Jan-2024
FEN: 8/8/8/8/8/5k2/8/6K1
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2024-01-18 more...
6 - P0003539
Hilding Fröberg
332 Land og Folk 01/03/1970
P0003539
(4+2) C+
h#1.5
1. ... Sf5? 2. 0-0-0?? Sd6# - aber die s0-0-0 ist illegal, den zuletzt muß Schwarz mit K oder T gezogen haben.

1. ... Sg8! 2. Td8 Sc7#
play all play one stop play next play all
Mario Richter: Luboš Kekely (Slovakia) correctly points out that 1. ... Sf5! 2. 0-0-0 Sd6# is only a try and not a solution (last black move must have been by King or Rook, so the queenside castling is illegal).
I have changed the solution accordingly. (2023-03-10)
comment
Keywords: Cant Castler, Castling (sg), Aristocrat, Minimal, Miniature, Homebase
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 & trivial retro-logic | C+ rawbats
FEN: r3k3/6K1/N6N/8/8/7B/8/8
Input: Gerd Wilts, 1995-06-03
Last update: Mario Richter, 2023-03-10 more...
7 - P0003767
Zvonimir Hernitz
Problem 41-44 03/1957
1. Lob e.a.
15. Thematurnier
P0003767
(2+4) C+
h#2*
1. ... Dxb5 2. Ka2 Db2# because WTM.
So set play 1. Da4 Db2# because position not required to be legal.
play all play one stop play next play all
A.Buchanan: The short retro try is presumably intended, else sTb5 would suffice (2021-10-16)
more ...
comment
Keywords: No legal last move for White, Aristocrat, Minimal, Miniature
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 & simple retro-thought
FEN: 8/8/8/1q6/8/k7/2br4/1QK5
Reprints: 6. Krumme Hunde 01/12/1970
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2023-12-06 more...
8 - P0004066
S. N. Ravishankar
2069 diagrammes 89 04-06/1989
P0004066
(2+1)
#1 vor 6
VRZ, Typ Proca
R: 1. Ke2xLf1 ~ 2. Kd3xLe2 ~ 3. Kc4xLd3 ~ 4. Kb5xLc4 ~ 5. Kb6-b5! ~ 6. Sa6xSb8, dann 1. Sc7#
play all play one stop play next play all
S N Ravi Shankar: This problem is not mine. (2019-01-02)
Mario Richter: My first guess for the solution was:
R: 1. Ke2xLf1 2. Kd3xLe2 3. Kc4xLd3 4. Kb5xLc4 5. Ka6xLb5 Lc6-b5+ 6. Sd7xLb8, dann 1. Sb6#, but that doesn't work because of 5. ... Ld7-b5+!
Does someone see (or know) the correct solution? (2019-01-03)
Henrik Juel: No, because with 1... Lh3-f1+, 5.Ka6-b5 thr. 6.Sd7xLb8 fails similarly on 5... Ld7-h3 (2019-01-03)
S N Ravi Shankar: Does adding a black knight on e6 cure? 1. Ke2xLf1 2. Kd3xLe2 3. Kc4xLd3 4. Kb5xLc4 5. Ka6-b5! followed by 6. Sd7xLb8 and now 1. Sb6#. (2023-02-20)
S N Ravi Shankar: The problem appears to be sound. 1.Ke2xLf1 2.Kd3xLe2 3.Kc4xLd3 4.Kb5xLc4 5.Kb6-b5! followed by 6.Sa6xSb8 and now 1.Sc7#. (2024-02-18)
A.Buchanan: WinChloe also gives the same composer. A curious situation, but at least the problem attributed to you appears to be sound! (2024-02-19)
Adrian Storisteanu: Above the "diagrammes" diagram there is: R. SHANKAR, Inde. In the volume index, under RETROS: this is the only problem of a composer named (just) "SHANKAR" (one original), while "RAVI SHANKAR" is a different author (with two originals). (2024-02-20)
A.Buchanan: I suggest that S.N.Ravishankar check the reaponse to the query (A='Shankar' or a='Ravishankar') AND NOT A='Shankar Ram, Narajan' as there are many other similar retros which are attributed to Ravishankar. If he can state here which ones are not his, I will happily modify the data. (2024-02-21)
more ...
comment
Keywords: Defensive Retractor, Type Proca, Rex solus (s), Aristocrat, Minimal, Miniature
Genre: Retro
FEN: kN6/8/8/8/8/8/8/5K2
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2024-02-21 more...
9 - P0005387
Nikita M. Plaksin
6557 feenschach 109 11/1993
P0005387
(2+2) C+
-1w, dann =1
R: 1. Ka3-a4?, dann 1. Lxa2=
R: 1. Ka3xBa4!, dann 1. Lxa2=
play all play one stop play next play all
Mit folgender witziger Begründung des Autors: "If on the board are only KL-KL (and LL on squares of the same colour), by the rules of chess an immediate draw occurs! Therefore, the retro move Ka3-a4 is illegal." Ein Fehllöser: "Reichlich trivial." Ein Ratloser: "... oder wie darf ich das sehen?" TK hatte den Durchblick: "Die doppelte Rücknahmemöglichkeit kann man aber gar nicht übersehen (und schon gar nicht der Autor). Einzige Möglichkeit: nur Ka3xBa4, weil andernfalls die Stellung schon vorher patt wäre. Aber, aber: das ist remis, kein Patt!!" FR: "Meine 'Ehrenlösung' für diese Gruppe (hoffentlich stimmt sie auch)." WM: "Nette Pointe. Das erzähl' ich meinen Kindern, daß ich einen PLAKSIN gelöst habe." 1,2/I
A harbinger of Dead Reckoning-style reasoning, before that rule ever existed. As sound today in 2018, as when it was composed under "insufficient material for mate" rule.
Henrik Juel: Nice to see that I am not the only freak who mixes english text with german notation (to avoid the ambiguous B)
Were you inspired by this problem in your work on Dead Reckoning, Andrew? (2020-05-04)
A.Buchanan: Ha no: when I stumbled across DP rule I knew even less about chess problems than I know now, if you can imagine, and had never encountered this one which Werner Keym unearthed and published it in "Out Of the Box". Ecclesiastes 1:9 says "There is nothing new under the sun." Mario made this point about origin of Schnoebelen promotions too. Gollon's intepretation of Chaturanga (the earliest known forebear of chess) offers fascinating possibilities for Schnoebelen promotion, which I am sure the Indian retrograde analysts of 7th Century CE were adept at exploiting, in tablets alas now lost. See https://www.chessvariants.com/historic.dir/chaturanga.html.

The "insufficient material" composition does perhaps explain Plaksin's openness to the concept of DP, at a time when perhaps some noses elsewhere were being turned up, as he later composed with Kornilov *27* other DP problems, all to be found in PDB. (2020-05-04)
Ladislav Packa: Interesting, but on YouTube I saw a game (one of the actors was Magnus Carlsson), which ended in a position with only two kings and one of the players still made a move. (2020-05-05)
A.Buchanan: http://wismuth.com/chess/illegal-moves.html contains many other games where GMs were unable to tear themselves away from playing the dead game. I think it's kind of sweet that the GMs just can't stop playing. Have you got a link to the Carlsen game please, Ladislav? (2020-05-06)
Ladislav Packa: I'm sorry, Andrew, but I don't remember. I've seen hundreds of games on youtube. But I encountered similar cases in my own practice, mostly a joke, and the game immediately ended with a smile and a handshake. (2020-05-06)
A.Buchanan: A completely different stipulation: -w, h=1 half-duplex (2024-01-11)
more ...
comment
Keywords: Help retractor, Dead Position, Aristocrat, Miniature, Minimal
Genre: Retro, Fairies
Computer test: C+ deadpos v2.1 8-Jan-2024
FEN: 8/8/8/8/K7/8/b7/kB6
Reprints: 440 Out Of the Box , p. 141, 2018
www.thbrand.de 14/01/2018
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2024-01-18 more...
10 - P0006328
Albert Heinrich Kniest
8114 FEENSCHACH 01-02/1967
P0006328
(1+3)
-1s, dann h=2
R: 1. Dg7xDb2, dann 1. Kh8 Dxa2 2. Df7+ Dxf7=
play all play one stop play next play all
Adrian Storisteanu: A bPa2 (instead of the bR) will suffice. (2021-04-23)
comment
Keywords: Help retractor, Aristocrat, Miniature
Genre: Retro, Fairies
FEN: 6k1/8/8/8/8/8/rq6/5K2
Input: Gerd Wilts, 1995-08-27
Last update: A.Buchanan, 2024-01-18 more...
11 - P0006339
Yosif Krikheli
8945 FEENSCHACH 09-10/1968
P0006339
(1+1) cooked
-1w -1s, dann h=1
2 Lösungen
1) R: 1. Kc5xDd6 Dd7xDd6, dann 1. Dc6 Dxc6=
2) R: 1. Kc5xBd6 c7xDd6, dann 1. c6 Dxc6#
play all play one stop play next play all
siehe 9200
mri: Mehrere NL, z.B. R: Kc6xLd6 Lc5xDd6 V: 1.Ka5-a6 Dd6xc5 oder R: Kc5xTd6 Tb6xDd6 V: 1.Tb6-c6 Dd6xc6 (2007-10-25)
Mario Richter: s. P0005054 (2009-12-31)
A.Buchanan: Reasonable to suppose that P0005054 is the correction (2024-01-15)
comment
Keywords: Help retractor, only Kings, Aristocrat, Miniature, Superseded by (P0005054)
Genre: Retro, Fairies
Computer test: C- Deadpos v2.3 14-Jan-2024
FEN: 8/8/3K4/k7/8/8/8/8
Input: Gerd Wilts, 1995-09-10
Last update: A.Buchanan, 2024-01-18 more...
12 - P0006639
Alexander Hildebrand
(40) Die Schwalbe 159, p. 366, 06/1996
3. Lob Ceriani-Gedenkturnier, 2. Abteilung
P0006639
(5+2)
#1
UW-Figuren in der Diagrammstellung sind 1) zulässig 2) unzulässig
1) 1. Se3#
2) 1. ... Txf1 2. Tfg3#, 1. ... Txh1 2. Thg3#
play all play one stop play next play all
Henrik Juel: C+ Popeye 4.61 (2022-01-02)
comment
Keywords: Non-standard material, Aristocrat, Minimal, Miniature, No legal last move for Black
Genre: Retro
FEN: 8/8/6K1/8/8/5R1R/6k1/5NrN
Input: Gerd Wilts, 1996-07-11
Last update: Mario Richter, 2022-01-02 more...
13 - P0007435
Adamas
(47) feenschach 40 11-12/1977
P0007435
(1+3) cooked
Welches war der letzte Zug?
Längstzüger
R: 1. Bd2xDe1=L+
play all play one stop play next play all
Cook: R: 1. Bd2xDc1=L+,d2xT/L/Sc1=L+
Mario Richter: Position is as given in 'feenschach'. It seems that R: 1. d3xDc1+,d3xT/L/Sc1+ also works and that adding a black pawn on the 7th rank (e.g. h7) would prevent the cook.
Can somebody confirm my observation? (2022-01-10)
Mario Richter: small typo: It seems that R: 1. d2xDc1+,d2xT/L/Sc1+ also works (2022-01-10)
Henrik Juel: Your observation, with last moves d2xDTLDc1=L+, seems correct (2022-01-10)
comment
Keywords: Maximummer, Last Move? (BxD=L), Aristocrat, Miniature
Genre: Retro, Fairies
FEN: 8/8/8/8/8/4K1k1/8/2b1b3
Input: Gerd Wilts, 1996-08-21
Last update: Mario Richter, 2022-01-10 more...
14 - P0007436
Adamas
(48) feenschach 40 11-12/1977
P0007436
(1+3) cooked
Welches war der letzte Zug?
Längstzüger
R: 1. Bg2xTh1=L+
play all play one stop play next play all
Cook: R: 1. Bg2xDf1=S+,Bg2xTf1=S+,Bg2xLf1=S+,Bg2xSf1=S+,
Henrik Juel: What is the other last move, Andrew? (2022-01-08)
A.Buchanan: I didn’t analyse these problems, just corrected the genre when I saw that it was incomplete. Here how about e.g. R: 1. Bc6-h8+ Kb7-a8 2. Bh8xPc6 (2022-01-09)
Mario Richter: R: 1. ... Bc6-h1+? is illegal - it leaves the wK in check!
The cooks are the discovered checks by 1. ... g2xYf1+ (2022-01-09)
comment
Keywords: Maximummer, Last Move? (BxT=L), Aristocrat, Miniature
Genre: Retro, Fairies
FEN: K7/8/8/8/8/8/7k/5n1b
Input: Gerd Wilts, 1996-08-21
Last update: Mario Richter, 2022-01-09 more...
15 - P0008784
Niels Høeg
The Chess Amateur 07/1926
P0008784
(1+1)
Längste BP ohne Schach. Welches war der letzte Zug?
R: 5899. Kg2xTh1
play all play one stop play next play all
The game ends after 50 consecutive moves without captures or pawn moves (loss of castling right is not included here), or when there is not enough material to mate (say K-K or K-KS). There are 30 captures and 96 pawn moves (including 8 pawn captures) available, so the longest game seems to last (30+96-8)x50=5900 moves. This cannot be achieved because of the move-loss when the draw-preventing move shifts between white and black. Niels Høeg believed that 2 moves were lost and stated the solution as 5898.- Kb7xTa8. Karl Fabel later showed that only 1.5 moves need be lost.

Since 1926, there have been some relevant innovations to rules and conventions
(1) 50 move rule applies only to retro compositions, and will trigger automatically (no issue with writing down the move). (Codex 1953?)
(2) Removal of rules about draw by insufficient material (Laws 1997)
(3) Dead position rule introduced (Laws 1997)
(4) 75 move rule introduced (Laws 2014)
(5) Dead position rule applies only to retro compositions (Codex 2015)
(6) Articles 9.2 & 9.3 apply to chess problems - this includes 50 move rule and excludes 75 move rule (Codex 2019)

This is certainly a composition rather than a question about over the board chess. And it is certainly a retro composition. So the 50 move rule will dominate the 75 rule. The standard interpretation of interaction between 50 move rule and Dead Position in compositions is that Dead Position assessment *is* aware of looming automatic draw by 50 moves. (Note there is a similar assessment for interaction between Dead Position and Draw by Repetition.)

So we can argue that the game cannot last to 5898.5 moves, because the final move leads to a mandatory draw: either the king captures the last officer, or the king avoids the capture and the game ends in draw under the 50 move rule. So the position is dead at 5898.0. But even 5898.0 is too long for the diagram position with the kings so far apart. In the alternate reality if the last capture of a rook does not take place, there must be sufficient moves left for the kings to come together so that the rook can deliver checkmate. This will take at least 6.0 moves.

There is also still an ambiguity in the rules as to whether checkmate overrides draw by 50 moves. This is explicitly mentioned in the 75 move rule, but not in 50 move rule. I assume that checkmate *does* take priority.

Or does a valid problem only exist in the context of the rules and conventions that pertained at the time of its composition? The Codex does not opine on this general point.

Compare P1331022

Duplicate Diagram: P1101148, P1189676, P1191185, P1304589

A.Buchanan: There's a question whether DP rule has visibility of 3Rep & 50M state. The current consensus among most of the tiny group who might care is that for retros, it does have visibility, but for purely forward problems, it does not. This align with the idea that by default 50M & DP rules apply only to retros (2023-09-06)
A.Buchanan: The old intended interpretation is protected under the Golden Age principle. Suppose we do apply modern rules, codex & clarifications. If Black just played Kb7xRa8, then the alternative leading to mate takes 7.0 moves, so this must have been Black's 5892nd move at the latest. If White just moved, then it was White's 5892nd at latest. So to maximize the length of the game, Black moved last. (2023-09-06) edit (2023-09-06)
more ...
comment
Keywords: Longest Proof Game, Last Move?, only Kings, Non-Unique Proof Game, Dead Position, 50 move rule, Constrained problem, Type A, Miniature, Golden Age (pre-dead), Aristocrat
Genre: Mathematics, Retro
FEN: k7/8/8/8/8/8/8/7K
Reprints: Schackproblemet 1928
Schach und Zahl 1966
Input: Gerd Wilts, 1997-06-20
Last update: A.Buchanan, 2024-01-18 more...
16 - P0576883
Dezsö Elekes
Uj Nemzedek 1923
P0576883
(1+1)
Schwarz nimmt einen Zug zurück, dann h=1
R: 1. Kg8xSf8, dann 1. Kh8 Kf7#
play all play one stop play next play all
Adrian Storisteanu: Try (or set play in the forward part): - 1.Kg8xBf8 & 1.what?? Bf8-g7=. (2021-05-07)
comment
Keywords: only Kings, Aristocrat, Miniature
Genre: Fairies, Retro
FEN: 5k2/8/6K1/8/8/8/8/8
Input: Felber, Volker, 2000-01-03
Last update: A.Buchanan, 2021-05-08 more...
17 - P1001360
Wilfried Neef
Hans-Peter Reich

Andernach TT 2001
3. Lob
P1001360a_1.png
(a: 2+2)
P1001360a_2.png
(a: 2+2)
A nach B in 9,5*
Beamtenschach
* 1. ... Tg1-f1+ 2. Kf2-e2 Tf1-d1 3. Sh1-f2 Td1-f1 4. Sf2-d1+ Kb2-a1 5. Sd1-c3 Tf1-e1+ 6. Ke2-d2 Te1-c1 7. Sc3-b5 Tc1-b1 8. Sb5-a3 Tb1-b2 9. Kd2-c1 Tb2-a2 10. Sa3-c2#
1. Sh1-g3 Tg1-f1+ 2. Kf2-e3 Tf1-f3+ 3. Ke3-e2 Tf3-c3 4. Sg3-e4 Tc3-c2 5. Ke2-d1 Tc2-c4 6. Se4-d2 Tc4-c2 7. Sd2-c4+ Kb2-a1 8. Sc4-a3 Tc2-d2+ 9. Kd1-c1 Td2-a2 10. Sa3-c2#
play all play one stop play next play all
Moldenhauer: Computerprüfung: C+ Jacobi v0.7.6 beta1 PG demolition mode
Notation B: 8/8/8/8/8//8/r1N5/k1K5 (2022-08-11)
more ...
comment
Keywords: A to B, Functionary Chess, Aristocrat
Genre: Fairies, Retro
FEN: 8/8/8/8/8/8/1k3K2/6rN
Reprints: feenschach 140 04-05/2001
Input: Gerd Wilts, 2001-09-04
Last update: Alfred Pfeiffer, 2019-03-26 more...
18 - P1108448
Werner Keym
Allgemeine Zeitung Mainz 1966
P1108448
(6+1)
#2
0. ... Kxc4 1. Db1
0. ... Kxe6 1. Dh7
play all play one stop play next play all
Henrik Juel: C+ Popeye 4.61, except for mate trials after 2... Kd5 (2022-02-15)
comment
Keywords: Symmetrical position, No legal last move for Black, Aristocrat, Miniature
Genre: Retro
FEN: K7/1N6/4R3/3k4/2R5/5N2/8/7Q
Input: Gerd Wilts, 2010-06-23
Last update: Rainer Staudte, 2022-02-15 more...
19 - P1112386
Mrs. W. J. Baird
(2) British Chess Magazine , p. 136, 03/1903
P1112386
(1+1) C+
Hilfsrückzüger
siehe Text
R: 1. Kf6xBg6, dann 1. ... Kh8 Kf7, dann R: sBh7xBg6, dann 2. ... g7#
play all play one stop play next play all
Originalforderung: 1) White to retract his last move 2) Black to play 3) White to play 4) Black retract a previous move so that 5) White can give mate with Pawn.
A.Buchanan: Deadpos v2 can now solve this, even though PDB animation can't manage to show it:
6k1/8/6K1/8/8/8/8/8 b }}= r1 }}= flip }}= m2 }}= flip }}= r1 }}= flip }}= #1 (p)
h5xRg6 flip then g8h7 h5h4 flip h6xPh7 flip then h7h8q#
f5xRg6 flip then g8h7 f5f4 flip h6xPh7 flip then h7h8q#
g5xPg6 flip then g8h7 g5f6 flip h6xPh7 flip then h7h8q#
g5xPg6 flip then g8h7 g5f6 flip h6xPh7 flip then h7h8r#
g5xPg6 flip then g8h7 g5h4 flip h6xPh7 flip then h7h8q#
g5xPg6 flip then g8h7 g5g4 flip h6xPh7 flip then h7h8q#
g5xPg6 flip then g8h7 g5f4 flip h6xPh7 flip then h7h8q#
f6xPg6 flip then g8h8 f6f7 flip h7xPg6 flip then g6g7#
nsols 8 (2024-01-05)
comment
Keywords: only Kings, Help retractor, Aristocrat, Miniature
Genre: Retro
Computer test: C+ deadpos v2.0
FEN: 6k1/8/6K1/8/8/8/8/8
Input: Frank Müller, 2010-08-06
Last update: A.Buchanan, 2024-01-05 more...
20 - P1128978
Ernest Pogosyants
Snannja ta prazja 1984
P1128978
(4+2) C+
#1
1. ... Txb2 2. Lxb2#
1. Txa2#? 1. Tb1#?
play all play one stop play next play all
RA1 SYK
more ...
comment
Keywords: Miniature Collection (0321214), No legal last move for Black, Aristocrat, Minimal, Miniature
Genre: n#, Retro
Computer test: C+ Popeye 4.61 and analysis
FEN: 8/8/8/8/8/B1N5/rR6/k1K5
Input: Zuncke/Bruder, 2010-09-11
Last update: A.Buchanan, 2023-12-05 more...
21 - P1131766
Fr. Mendel
89 150 Schachkuriositäten 1910
P1131766
(5+1) cooked
-1w, dann #2
R: 1. b7-b8=S, dann 1. Ld8 Ka6 2. b8=S#
R: 1. b7-b8=S, dann 1. Ld8 Kb8 2. Sc6#
play all play one stop play next play all
Cook: R: 1. Sa6-b8, dann 1. Lc5+! Kxa6 2. Ta7#
R: 1. Sa6-b8, dann 1. Lc5+! Ka8 2. Ta7#
Henrik Juel: The forward play is 1.Ld8 Ka6/Kb8 2.b8=S/Sc6# (2022-10-14)
comment
Keywords: Miniature Collection (0011852), Help retractor, Aristocrat, Miniature, Promotion in the retro play (S), Promotion in forward play (S)
Genre: 2#, Retro
FEN: 1N6/k3BR2/8/8/3N4/2K5/8/8
Input: Felber, Volker, 2010-09-11
Last update: A.Buchanan, 2024-01-18 more...
22 - P1143600
Tivadar Kardos
Feladvanykedvelök Lapja 1971
P1143600
(4+1) C+
#1
1. ... Kxe8 2. Dg8#
1. ... Kxc8 2. Da8#
play all play one stop play next play all
RA1 A12DD3
more ...
comment
Keywords: Miniature Collection (0321180), Aristocrat, Miniature, No legal last move for Black
Genre: n#, Retro
Computer test: Juel: C+ Popeye 4.61
FEN: 2NkN3/8/3K4/3Q4/8/8/8/8
Input: Zuncke/Bruder, 2010-09-11
Last update: Dieter Berlin, 2023-08-15 more...
23 - P1152187
Ernest Pogosyants
Snannja ta prazja 1984
P1152187
(4+2)
#1
1. ... Txh7 2. Tf8#
1. Tg7#? 1. Sf6#?
play all play one stop play next play all
RA1
Henrik Juel: C+ Popeye 4.61 and analysis
not 1.Tg7? because Black has the move (2022-07-19)
comment
Keywords: Miniature Collection (0321213), No legal last move for Black, Aristocrat, Minimal, Miniature
Genre: n#, Retro
FEN: 6kr/5R1N/4K2B/8/8/8/8/8
Input: Zuncke/Bruder, 2010-09-12
Last update: A.Buchanan, 2023-12-04 more...
24 - P1161509
Awenir G. Schaposchnikow
10 Schach (Borowitschi) 14 10/1987
P1161509
(4+1) C+
#3
1. ... Kxh7 2. Lf8 Kh8 3. Lg7+ Kh7 4. Sf6#
1. Lf8? Kxh7 2. Sf6+ Kh8 3. Lg7# but BTM
play all play one stop play next play all
RA3
A.Buchanan: A unique retro try adds value to a Article 15 problem, but there's no good way to denote this in the stipulation. Here "*" is tried, but this would normally apply to White losing the first move, e.g. P1394496. Nor is this line a regular try, denoted "v". Instead, I feel the need for a new symbol maybe "^" to denote a clean retro try. What do you think? (2021-10-12)
Henrik Juel: I would leave the stipulation as the author originally had it: just #3
and let the solver figure out what is going on (2021-10-12)
A.Buchanan: OK done - thank you Henrik (2021-10-18)
more ...
comment
Keywords: Miniature Collection (0342522), Aristocrat, Miniature, No legal last move for Black
Genre: 3#, Retro
Computer test: Popeye v4.87
FEN: 4N2k/4BK1N/8/8/8/8/8/8
Input: Zuncke/Bruder, 2010-09-12
Last update: A.Buchanan, 2021-10-18 more...
25 - P1165717
Ernest Pogosyants
Snannja ta prazja 1984
P1165717
(5+2) C+
#3
1. ... Txh3+ 2. Kf4 Txf3+ 3. Dxf3+ Kg1/Kh2 4. Dg2#
play all play one stop play next play all
RA3 SYp m
Henrik Juel: 0... Txh3+ 1.Kf4 Txf3+! 2.Dxf3+ Kg1,Kh2 3.Dg2#
0... Tg2+? 1.Dxg2#
0... Txf2? 1.Sxf2# (2022-07-19)
more ...
comment
Keywords: Miniature Collection (0341851), No legal last move for Black, Aristocrat, Minimal, Miniature
Genre: 3#, Retro
Computer test: HC+ Popeye 4.61 and analysis
FEN: 8/8/8/8/8/5NKN/5Q1r/5B1k
Input: Zuncke/Bruder, 2010-09-12
Last update: A.Buchanan, 2023-12-04 more...
26 - P1294321
Andrew Buchanan
www.anselan.com 2001
P1294321
(1+2)
Black to move. Last move?
R: 1. Kb8xSa8
play all play one stop play next play all
Compare P0001033.
Gerald Ettl: steht der sLh5 vielleicht auf h2 ?? (2023-07-02)
SCHRECKE: Why not R: Kb8xLa8? (2023-07-03)
Mario Richter: Wie "SCHRECKE" mit seiner Frage schon illustriert hat: mit dem sL auf h2 wäre das Problem inkorrekt, da neben R: 1. Kb8xSa8 auch R: 1. Kb8xLa8 als letzter Zug möglich gewesen wäre. Grund sind die etwas verwirrenden Dead-Reckoning-Regeln: mit sLh5 kann zuletzt nicht Kb8xLa8 geschehen sein, da in der Stellung wKb8 - sKb6 sLh5 sLa8 wegen der unzureichendes-Material-zum-Mattsetzen-Regel das Spiel schon in dieser Position beendet gewesen wäre, der wK als gar nicht mehr zur Ausführung eines Zuges geommen wäre ... (2023-07-03)
Mario Richter: Dear James, I suggest that you undo last change and put the black bishop back on h5! (2023-07-03)
A.Buchanan: There are 17 valid squares for the wB. Got to be on a light square for reasons given. Also it can't occupy or attack c8. And can't be attacking a8 because BTM. I think h5 selection was random, but could argue for any. (2023-07-04)
A.Buchanan: Or maybe bBa4, with which White by his last move avoided a completely sound #12. (2023-07-04)
Gerald Ettl: Dann waere es vielleicht ganz sinnvoll man schreibt die Bedingung unter das Diagramm. (2023-07-04)
A.Buchanan: Hi Gerald, it's not a condition, it's a FIDE rule since 1997, invented by a problemist who is also a rules committee member (Igor Vereschchagin) and approved by the rules committee (headed by FIDE Head International Arbiter Stewart Reuben), backed up by a WFCC convention since 2015 (Kjell Widlert & Michel Caillaud, responding to a request from some endgame studiers who understood that it was a real thing. Like 50M rule, it applies by default for retro problems. And the PDB keywords here give the game away anyway. If it was a forward stipulation, then I would indeed add a stipulation, e.g. P1208623. Please enjoy the madness that is DP rule :) P.S. I have found recently that it was really invented by Shakespeare. (2023-07-04)
Gerald Ettl: Ich spiele nicht nach den FIDE-Regel. (2023-07-04)
Olaf Jenkner: Allright.
https://www.skat-online.com/regeln-hilfe/regelwerk/internationale-skatordnung.html (2023-07-05)
comment
Keywords: Type B, Last Move? (KxS), Dead Position, Economy record (Last Move? Type B), Rex solus (W), Aristocrat, Miniature, Minimal
Genre: Retro
FEN: K7/8/1k6/7b/8/8/8/8
Reprints: Retros mailing list 20/02/2007
Input: A.Buchanan, 2015-01-07
Last update: James Malcom, 2023-07-03 more...
27 - P1339695
Kostas Prentos
09 Belgrade Sake Tourney 2016
2. ehrende Erwähnung
P1339695
(6+0)
h#2
2 Lösungen
Colorless chess
Kostas Prentos: Solution:
1. Le7(=b) Kh5(=w, bKa4, wTb5, wLe8) 2. La3 Sb6(=w)#
1. Lg3(=b) Se3(=w) 2. Kh4(=b, wKa4) Th5(=w, wLe8)# (2022-12-08)
comment
Keywords: Colorless chess, Aristocrat
Genre: h#, Retro, Fairies
FEN: 4B3/8/8/1R6/K1N3KB/8/8/8
Reprints: 09 Problem Paradise 74, p. 47, 04-06/2016
Input: A.Buchanan, 2017-09-18
Last update: Alfred Pfeiffer, 2017-09-19 more...
28 - P1368554
Andrew Buchanan
OzProblems.com 16/10/2019
P1368554
(4+3) C+
Gewinn
1. Sd3! Kf8 2. Se3 Sg6+ 3. Kd4 Td8+ 4. Kc3 Tc8+ 5. Sc4 Kg7 6. Sf2 Sh8 7. Tf1 Sf7 8. Se4 Td8 9. Sf6 Sg5 10. Se3 Ta8 11. Kb4 Tb8+ 12. Kc4 Tc8+ 13. Kb5 Tb8+ 14. Kc6 Ta8 15. Sfd5 Ta3 16. Kb5 Se4 17. Te1 Sg5 18. Kb4 Ta2 19. Tf1 Kg6 20. Tf6+ Kh5 21. Kb3 Ta7 22. Sf4+ Kh4 23. Se2 Tb7+ 24. Kc4 Sf7 25. Tf1 Kg5 26. Sd4 Se5+ 27. Kd5 Sd3 28. Se6+ Kg6 29. Sf8+ Kg5 30. Ke4 Sc5+ 31. Kd4 Sd7 32. Se6+ Kg6 33. Sd5 Ta7 34. Se7+ Kh5 35. Tg1 Ta4+ 36. Ke3 Tg4 37. Ta1 Sb6 38. Kf2 Sd7 39. Ta8 Tc4 40. Tg8 Tc2+ 41. Ke3 Tc3+ 42. Kf4 Tc4+ 43. Kf5 Kh4 44. Sf4 Sf6 45. Tg2 (thr 46.Sg6#) Tc5+ 46. Kxf6 Tc6+ 47. Kf5 Tc5+ 48. Sed5 (thr 49.Tg4#) Txd5+ 49. Sxd5 (switch to Syzygy DTM) Kh3 50. Sf4+ Kh4 51. Tg4#
Compare 44. ... Tc5+ which gives a longer DTM at the cost of a slightly sub-optimal DTZ. 45. Sed5 (thr 46.Tg4#) Txd5+ 46. Sxd5 (switch to Syzygy DTM) Kh3 47. Tc8 Kg3 48. Ke6 Sb6 49. Sxb6 Kf2 50. Sc4 Ke1 51. Td8 Ke2 52. Td2+ Ke1 53. Kd5 Kf1 54. Ke4 Kg1 55. Kf3 Kh1 56. Kg3 Kg1 57. Td1#
play all play one stop play next play all
According to the Syzygy tablebase, *any* move wins for White except the silly 1. Sa2??
However, the tablebase does not know about castling!
The quickest winning move 1. Sd3!? would be defeated by 1. ... 0-0-0!? which attacks Sd3 and threatens the skewer Re8+. After this, White can only draw - or even loses after 2. Sc1??
But by a simple retro argument, Black cannot castle.
Since this retro point is essential to the solution, we have a retro problem, and hence the 50 move rule, which by Codex default is disengaged, is switched on.
When working with the 50 move rule, the key concept is not the number of moves to mate, but the number of moves to the first capture, pawn move or checkmate, known as DTZ.
All the alternatives to 1. Sd3 take more than 50 moves to force the first capture. The closest are 1. Sc3 & Se3 which according to Syzygy require exactly 50.5 moves, so seem *just* too slow. (For positions close to the cut-off, one has to be careful about *rounding*, see https://syzygy-tables.info/metrics. The number of half-moves for DTZ can be n or n+1. In fact here, after 1. Sc3/Sf3, the zeroing move is at its earliest White's 52nd move, not 51st.)
By the retro property therefore *only* 1. Sd3!, which requires 45 moves to force the first capture, can win. So this removes all the cooks for the first White move.

Lomonosov DTM #59: 1. Nd3!! Kf8!! 2. Ne3! Ng6+! 3. Kd5 Rd8+ 4. Kc4 Rc8+ 5. Kb5 Rb8+ 6. Ka6 Kf7 7. Nc5 Ne5 8. Nd5 Re8 9. Kb7 Nc4 10. Rf1+ Kg7 11. Kc6 Re5 12. Nd3 Re6+ 13. Kc5 Ne5 14. N3f4 Nd7+ 15. Kb5 Rd6 16. Nc7 Kf7 17. Nfd5+ Kg6 18. Ne7+ Kg5 19. Ncd5 Kg4 20. Rf4+ Kg5 21. Rf2 Kg4 22. Ne3+ Kg5 23. N7d5 Kg6 24. Rf1 Nf6 25. Nf4+ Kf7 26. Nc4 Rd8 27. Ne5+ Kg8 28. Rg1+ Kh7 29. Kc6 Rc8+ 30. Kd6 Re8 31. Re1 Ra8 32. Rh1+ Kg8 33. Ke7 Ra4 34. Rg1+ Kh7 35. Ne6 Nd5+ 36. Kd6 Nf4 37. Nc5 Rd4+ 38. Ke7 Rd2 39. Rg4 Rf2 40. Ncd7 Nd5+ 41. Ke6 Nf4+ 42. Kd6 Rd2+ 43. Ke7 Nd5+ 44. Kf8 Kh6 45. Rh4+ Kg5 46. Nf3+ Kf5 47. Nxd2 (zeroing 50M) Nc7 48. Re4 Ne6+ 49. Ke7 Nf4 50. Nf6 Ng6+ 51. Kf7 Ne5+ 52. Kg7 Kg5 53. Nf1 Kf5 54. Ne3+ Ke6 55. Nc4 Ke7 56. Rxe5+ Kd8 57. Rc5 Ke7 58. Rd5 Ke6 59. Re5# 1-0.
http://www.ozproblems.com/walkabout/walkabout2019#WA1610
https://www.chess.com/blog/Rocky64/a-heraldic-endgame-tablebase-composition

The school shield which inspired the problem:
http://www.calvert-trust.org.uk/images/colour.jpg
Henrik Juel: With White to move, last move was made with Ta8 or Ke8, so Black may not castle
An endgame connaisseur may supply the solution... (2019-10-25)
James Malcom: It is now supplied, Henrik. :) I worked through the Sygyzy tablebase, move by move, to get the computer recommended line. (2020-10-09)
A.Buchanan: Thanks James for this hard work to record a solution. Alas there is not just a single recommended line - White has a choice as early as W3. I wonder too if there is a DTM line which is faster than #57, and still clears the DTZ hurdle although maybe not as quickly as B45 as here. There is no DTM engines for 7 pieces yet.
What is certain is that the key works, and is unique. The exactly details of the best mating line remain to be revealed by improving technology. (2020-10-09)
A.Buchanan: For example, 2. Nc5 has DTZ 90, compared to the "superior" 2. Ne3 DTZ 88. However, if you keep picking the top move all the way through, then the final DTZ is in fact checkmate! I haven't all the Black choices though, but there aren't that many of them (2020-10-09)
A.Buchanan: The Lomonosov tablebase is DTM, and is available for free on Android. Today I found a PC app called Blue Stacks which emulates Android. According to Lomonosov, the position is #59, compared to Syzygy's DTZ offering #57 via zero at B45. When I run through the L. indicative solution (very quick to download and grab all of it), it is close to S.'s choices and all the mainline positions are safe from 50M. The zero is at W47, and the final mate is attractive in the middle of the board.
The real questions are:
(1) Is the #59 sound from 50M perspective? Or can Black force White to delay a few moves in order to avoid 50M trouble somewhere?
(2) How dualized is the solution? How does 50M play into pruning that?
What is clear is that both tablebases agree the solution begins 1. Nd3!! Kf8!! 2. Ne3! Ng6! (2020-10-10)
A.Buchanan: James' Syzygy solution had seemed a little odd, because it seemed to go against Syzygy's assertion that DTZ=n means that zeroing happens at n or n+1 ply (it's not exact because of Syzygy's rounding of the units bit of the integers, which apparently saves a vast amount of data, and is allegedly "safe"). But James's solution has zeroing at n-1. If Black was indeed forced to zero prematurely in this way, this would show a bug in Syzygy.

In no sense is this a criticism of James: for whose talent, hard work & existence I am incredibly grateful. But it turns out there is a tiny issue in the solution he posted, just before DTZ=0.

Quarantine lockdown in Hong Kong has given me a chance to look at the position after W44, https://syzygy-tables.info/?fen=6R1/3nN3/8/5K2/2r2N1k/8/8/8_b_-_-_0_1, Black has two choices Tc5+ & Sf6. James chose the first for simplicity, as sensibly he always did, but 45. Sed5 threatens 46. Tg4#. The only way to avoid this 45. ... Txd5+ prematurely zeroing. But Syzygy makes no promises about DTM - it just happens that the random path that James found has mate as the zeroing move! This is not typical, so a better illustrative solution has 44. ... Sf6. With best play by both sides, I think this results in mate at W51.

How to compare this with the Lomonosov solution with mate at W59? How is it possible that Syzygy, with the extra constraint of avoiding 50M draw, has found a *shorter* mate? If you think about it, there is no issue here. Syzygy is only focusing on DTZ, and there are many points in the long solution at which there are choices of equal DTZ. What Lomonosov tells us is that Black can somehow force a Syzygy branch which gives #59 or longer. For 6 or 7 pieces, we just don't have the visibility in Syzygy to find that DTM path. That is the explanation. However for 5 pieces, Syzygy also gives us the DTM value, and as long as one has escaped 50M range, it makes case to switch to that as soon as 5 pieces are reached. (2022-08-05)
A.Buchanan: As problemists, what we would really like to know is the minimum number of moves to mate, while not falling foul of 50M. Even with both DTZ & DTM values known, this is not easy to find. Here is a toy example to show one difficulty: https://syzygy-tables.info/?fen=7k/8/7K/4P2R/8/8/8/8_b_-_-_0_1 Black's forced move leads to DTZ=1 DTM=3, but White must choose which he wants to achieve, as they are mutually exclusive. If the 50M clock is low, 1.e6 gives DTM=16. But otherwise 1.Rf5 gives DTM=2. Now White will know which he wants, but Black is usually free to decide whether to defend the DTZ or the DTM or potentially to delay the commitment. The tactical richness of a position is not captured by simply the DTZ & DTM values (2022-08-05)
A.Buchanan: OK it turns out that what I'd been arguing for already exists to some extent: it's called DTM50 - see http://galen.metapath.org/egtb50/ (2022-08-05)
comment
Keywords: Cant Castler, Aristocrat, 50 move rule, Miniature
Genre: Retro, Studies
Computer test: www.syzygy.com
FEN: r3k2n/8/8/4K3/8/8/8/2NNR3
Reprints: www.chess.com 17/10/2019
Input: A.Buchanan, 2019-10-25
Last update: A.Buchanan, 2022-08-05 more...
29 - P1377353
Isaak S. Birbrager
25 Fascinating Chess [Birbrager] , p. 36, 1961
P1377353
(6+1) cooked
Take back a move and then #1
R: 1. 0-0, dann 1. 0-0-0#!
play all play one stop play next play all
Cook: R: 1. Ta2-a1, dann 1. Td1#
R: 1. Tf2-f1, dann 1. Td1#
R: 1. Tc1-a1, dann 1. Tfd1#
See P1388716 for fairy fix

Originalforderung: Matt in Null Zügen (mit der Argumentation, daß (-1) Zug + (+1) Zug = 0 Züge ergibt.)

Autorschaft Birbragers zweifelhaft, da das Buch eher eine Sammlung von Problemen namhafter Autoren ist. Im Vorwort zur russischsprachigen Ausgabe heißt es: "В этой своей работе автор обратился к творчеству титанов шахматной мысли Росси М. Чигорина, А. Петрова, И. Шумова, советских шахматных композиторов А. Гуляева, В. Чеховера, А. Гербстмана, а также ряда зарубежных авторов."
Adrian Storisteanu: How about e.g., - 1.Rc1-a1 & 1.Rf1-d1# ?! (2021-04-18)
Henrik Juel: Yes, that is a bad cook (2021-04-18)
A.Buchanan: I wish that some solving engine could retract moves without regard for legality, to allow for Baird-style helpmate retractors to be tested after all these years. For this aristocrat with no units adjacent to bK, a reasonable approximation to the stipulation is: ser-#2. Of course it misses the uncastling, but it does derive:
1. Ta2 2. Td1#
1. Tf2 2. Td1#
1. Tac1 2. Tfd1#
I don't see any way to eliminate the third of these cooks in an orthodox problem. However Bosma can come to the rescue! I don't see a way to keep it as a miniature though. I will post it separately. (2021-04-18)
Mario Richter: Anmerkung zur Quelle: Es gibt kein Buch "Unterhaltsames Schach" bzw. "Fascinating Chess", der Titel sollte auch in der deutschen und englischen Version als Transkription (oder Transliteration?!) des Originaltitels angegeben werden!
Das hier um so mehr, als es tatsächlich eine englischsprachige Ausgabe dieses Buches mit dem Titel "Chess: Serious; for Fun" aus dem Jahre 1975 gibt (Verlag CHESS Ltd., Sutton Coldfield, England)

Zur Autorschaft: Daß Birbrager der Autor dieses und anderer Probleme aus dem Buch ist, ist eher unwahrscheinlich (s. Vorwort). (2021-04-18)
James Malcom: Mariom the book does exist: https://www.google.com/books/edition/%D0%97%D0%B0%D0%BD%D0%B8%D0%BC%D0%B0%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D1%8B%D0%B5_%D1%88%D0%B0%D1%85%D0%BC%D0%B0%D1%82/ZPbTxQEACAAJ?hl=en

I don't know why PDB will not accept ????????????? ???????" as the source, so I had to make do with a translation.

Furthermore, I only know of it thanks to a chess.com comment: https://www.chess.com/blog/Rocky64/what-if-a-pawn-could-promote-to-a-pawn#comment-49584342

I messaged them last June, and you can actually download the book for yourself (this link is safe): ftp://nozdr.ru/biblio/games/chess/1942-1991/%D0%91%D0%B8%D1%80%D0%B1%D1%80%D0%B0%D0%B3%D0%B5%D1%80%20%D0%98_%20%D0%97%D0%B0%D0%BD%D0%B8%D0%BC%D0%B0%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D1%8B%D0%B5%20%D1%88%D0%B0%D1%85%D0%BC%D0%B0%D1%82%D1%8B%20(1961).djvu

Lastly, despite the foreword, I interpret these 14 problems to be Birbrager's interpretations of other's ideas, making them his technically. (2021-04-19)
comment
Keywords: Castling as mating move, Help retractor, Rex solus (s), Miniature, Aristocrat, Castling in the retro play
Genre: Retro
Computer test: C- Popeye for ser-#2 sufficient to demonstrate cooks for the actual stipulation
FEN: 8/8/3N4/3N3B/8/3k4/8/R4RK1
Input: James Malcom, 2020-06-28
Last update: Mario Richter, 2021-04-18 more...
30 - P1379897
Frank Fiedler
v Wochenpost 52 1984
P1379897
(2+4)
-1(s+w), dann #1
R: 1. Dh3xTh1# Tg2-e2, dann 1. 0-0#
play all play one stop play next play all
Adrian Storisteanu: A try: - 1.Qh5xRh1# pass & 1.0-0#. (2021-04-25)
comment
Keywords: Help retractor, Aristocrat, Castling
Genre: Retro
FEN: 8/8/7r/8/4n3/8/4R3/1k2K2q
Reprints: N6) Heureka! 1/92, p. 7, 07/1992
Input: Alfred Pfeiffer, 2020-09-12
Last update: Alfred Pfeiffer, 2020-09-12 more...
31 - P1384539
Henrik Juel
Thema Danicum 2004
Spezialpreis
P1384539
(18+0)
Färbe die Steine
a) White Kf3, Pd3,d5,d7,e4,e7,f5,g2,h3 Black Ka3, Pb2,e2,e3,e5,e6,f7,g7,h5
play all play one stop play next play all

Duplicate Diagram: P1017583

Henrik Juel: Solution
All 8+8 pawns are on the board, and it is easy to count the east-bound pawn captures needed to give the diagram configuration
The a-file is pawnless, axb happened twice, bxc happened 2+2-1 = 3 times, cxd happened 3+2-0 = 5 times, and dxe happened 5+2-3 = 4 times, for a total of 14 needed captures; this number equals the number of missing officers, 7+7, so all captures were pawn captures, namely the ones just enumerated
This means that the pawns on the f,g,h-files never captured, so Pf5,g2,h3 are white and Pf7,g7,h5 are black
A sKf3 would stand in impossible check from wPg2, so Kf3 is white, and Ka3 and Pb2 are black
A sPe4 would give impossible check to wKf3, so Pe4 is white
[Lf1,Lf8] were not captured at home, so Pe2 is black and Pe7 is white
Now we have two white pawns on the e-file, so the white capture dxe happened at least once; this leaves at most six captures for the remaining three white pawns, and to reach the diagram configuration we need all these six captures, namely axbxcd, bxcxd, and cxd
This means that Pd3,d5,d7 are white and Pe3,e5,e6 are black, concluding the coloring
It is easy to verify that this coloring is a legal position; the only pitfalls in constructing a proof game are on the e-file, where Pe4 must be [wPe2] and Pe5 or Pe6 must be [sPe7] to ensure that the black e-pawn stands above the white one (2020-12-31)
Henrik Juel: The colored position is
White Kf3, Pd3,d5,d7,e4,e7,f5,g2,h3
Black Ka3, Pb2,e2,e3,e5,e6,f7,g7,h5 (2020-12-31)
comment
Keywords: Colouring problem, Aristocrat, Miniature, Kindergarten Problem
Genre: Retro
FEN: 8/3PPPP1/4P3/3PPP1P/4P3/K2PPK1P/1P2P1P1/8
Input: fs/hg, 2020-12-30
Last update: A.Buchanan, 2023-06-03 more...
32 - P1386945
Werner Keym
Augsburger Allgemeine 13/02/2021
P1386945
(6+1) C+
#2
1. ... Kxh7! 2. Le4+ Kg8 3. Sh6#
1. ... Kxf7! 2. Lf8 Ke6 3. Dd5#
2. ... Ke8 3. De7#
1. Sh6+? Kxh7 2. Le4#
play all play one stop play next play all
Schwarz hat keinen letzten Zug!
A.Buchanan: Werner opened my eyes to the delights of these “official jokes” sanctioned by Codex Article 15 through his book Eigenartige Schachprobleme. The animation does not handle them well, as the move numbering and the ordering has to be distorted as here (2021-03-04)
A.Buchanan: I expect that Werner will be delighted with this one, as it has very clean solutions and retro try, which is his aim. (2021-03-04)
more ...
comment
Keywords: Miniature, Symmetrical position, No legal last move for Black, Aristocrat, Rex solus (s), Asymmetrical solution
Genre: Retro, 2#
Computer test: Henrik Juel: C+ Popeye 4.61 (2021-03-03)
FEN: 6k1/5NBN/8/6Q1/8/8/6B1/6K1
Input: Gerd Wilts, 2021-03-03
Last update: Alfred Pfeiffer, 2021-07-30 more...
33 - P1387362
Manfred Zucker
Freie Presse (Chemnitz) 24/06/1977
P1387362
(1+1)
Wie viele verschiedene letzte Züge sind möglich?
29 Lösungen
play all play one stop play next play all
Gefragt war natürlich nach dem letzten Einzelzug. Nun kann zuletzt sowohl der weiße als auch der der schwarze König gezogen haben. Der weiße König kann von drei verschiedenen Feldern (a2,b1,b2) gekommen sein, und er kann auf a1 eine schwarze Dame, einen schwarzen Turm, einen schwarzen Läufer, einen schwarzen Springer oder nichts geschlagen haben, das sind 3x5=15 Möglichkeiten. Dasselbe trifft auf den schwarzen König zu, insgesamt ergeben sich so 30 Möglichkeiten für den letzten Zug - und doch ist diese Lösung nicht richtig! Die Stellung wKb2-sLa1 ist partiemöglich (letzte Züge: 1. ... a2-a2=L+! 2. Kxa1), die Stellung sKg2-wLh1 jedoch nicht, denn der weiße Läufer kann (bei schwarzer Königsstellung auf g2) auf keine Weise nach h1 gekommen sein! Diese partieunmögliche Stellung war also zu subtrahieren, das richtige Ergebnis mußte "29" lauten.

Duplicate Diagram: P1207607

Dazu schreibt die FP: "Wie viele verschiedene letzte Züge sind möglich? Noch ein kleiner Hinweis: Beachten Sie beim Zählen bitte auch, daß die Könige zuletzt geschlagen haben können.".

(MZ433)
.
Henrik Juel: solution
2x3x5 - 1 = 29
R: Kg2xLh1 is illegal (2021-03-12)
A.Buchanan: This preceded the DP rule by 20 years, so under “Golden Age” principle, that rule does not apply, although it would be sound either way. Under DP rule there would have been 2x2x3=12 possible last moves, as a rook or queen must have just been captured (2021-03-13)
A.Buchanan: Is an only kings position an aristocrat or a kindergarten? :) Is it a one liner? :) I think the answer should be no, no and no (2021-03-13)
comment
Keywords: Aristocrat, Miniature, only Kings, Golden Age, Last Move?, Symmetrical position, Asymmetrical solution
Genre: Retro, Mathematics
FEN: 8/8/8/8/8/8/8/K6k
Input: Felber, Volker, 2021-03-12
Last update: A.Buchanan, 2021-03-13 more...
34 - P1388716
Andrew Buchanan
PDB Website 18/04/2021
after Isaak S. Birbrager
P1388716
(7+1)
-1w, dann #1
Bosma
See P1377353
Mario Richter: In what sense does "Bosma" help here? (e.g. why does it exclude Solutions like R: Tf4-f1, dann 1. De2#?) (2021-04-18)
A.Buchanan: 1. Tf4? 2. De2+? Kc4!
It would be nice to find a position with more Bosma tries than 4 (2021-04-18)
A.Buchanan: WinChloe finds zero solutions for ser-#2, which is promising. (2021-04-19)
comment
Keywords: Help retractor, Aristocrat, Castling as mating move, Castling in the retro play, Bosma, Rex solus (s)
Genre: Retro, Fairies
FEN: 8/8/1N2Q3/7B/N7/3k4/8/R4RK1
Input: A.Buchanan, 2021-04-18
Last update: A.Buchanan, 2024-01-18 more...
35 - P1389077
Adrian Storisteanu
Discord Chess Problems & Studies Server 4/4/2021
2. Platz
CP&S Discord Server Composition Tourney 0 {}
P1389077
(3+2)
Switcheroo # =<1* (-:
(i.e. swap two pieces for mate in one or less)
1. De4# but faster is:
Swap Tc4<->Ba1 and now 1. Ta1->d1, completing 0-0-0#
play all play one stop play next play all
PR Edderiofer wrote: "Another mid-castling position. "=1" here initially suggested to me "in 0 or 1 plies", but of course, 0.5 = 1 too. (Should that be 0.25 if it's in a helpmate? I don't know.)"
Henrik Juel: based on the keywords, probably
switch La1 and Tc4, then 1.Td1#, i.e. complete the castling (2021-04-30)
comment
Keywords: Joke, Aristocrat, Minimal, Miniature, Castling (Complete or retract)
Genre: Retro
FEN: 8/8/8/4Q3/2R5/3k4/8/b1K5
Reprints: MatPlus.net Forum 4/4/2021
Input: A.Buchanan, 2021-04-29
Last update: Alfred Pfeiffer, 2021-07-27 more...
36 - P1389595
Otto Trinks

P1389595
(2+1) cooked
-1w,1s, dann h#1
R: 1. Bc7xTb8=L Tb7-b8, dann 1. Ta7 c8=D#
play all play one stop play next play all
Der letzte Zug von Weiß muß: Bc7xTb8 und wird Läufer gewesen sein. Schwarz hat vorher Tb7-b8+ gezogen. Nach Rücknahme des letzten Zuges von Weiß und des letzten Zuges von Schwarz ergibt sich daher die Stellung : Weiß: Kh8 Bc7; Schwarz: Ka8, Tb7. Schwarz zieht daher jetzt, um das Matt in einem Zug zu ermöglichen: Tb7-a7 worauf Weiß mit c7-c8=D matt setzt.
Cook: Co-NLs
R: 1. Ba7xLb8=L Kb7xTa8, dann 1. Ka6 axb8=D,axb8=T
R: 1. Ba7xSb8=L Kb7xTa8, dann 1. Ka6 axb8=D,axb8=T
Forderung im 'Boten von der Ybbs': "Weiß nimmt seinen letzten Zug zurück, dann nimmt Schwarz seinen letzten Zug zurück und dann zieht Schwarz so, daß Weiß in einem Zug matt-setzen kann!"

Motto: "Das Waidhofner Problem"

als Autor ist angegeben "Dr. S. Knirt", dabei dürfte es sich um ein Pseudonym von Dr. Otto Trinks handeln (S.Knirt rückwärts gelesen ergibt trinKS)
Adrian Storisteanu: See P0002517. (2024-03-19)
comment
Keywords: Help retractor, Aristocrat, Minimal, Miniature, under-promotion (L), Promotion in the mating move
Genre: Retro
FEN: kB5K/8/8/8/8/8/8/8
Reprints: 13 Bote von der Ybbs 28/12/1929
Input: Mario Richter, 2021-05-14
Last update: Alfred Pfeiffer, 2021-08-16 more...
37 - P1397486
Dmitri W. Pronkin
Andrey Frolkin
Werner Keym
Boris Tummes

Rund um die Retroanalyse 25/12/2021
P1397486
(14+14) cooked
BP in 59.0
1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 5. h4 d5 6. h5 d4 7. h6 d3 8. h7 dxc2 9. d4 a5 10. Lh6 c1=T 11. e4 Tc5 12. Se2 Th5 13. e5 c5 14. e6 Sc6 15. b8=T a4 16. Tb4 a3 17. Ta4 c4 18. b4 c3 19. b5 c2 20. b6 c1=T 21. b7 Tc4 22. b8=T Da5+ 23. Tbb4 Lb7 24. Sbc3 0-0-0 25. exf7 e5 26. Tc1 Lc5 27. f8=T a2 28. Tf3 a1=D 29. Sa2 g1=D 30. Tfa3 Dg6 31. f4 De8 32. f5 g5 33. f6 g4 34. f7 g3 35. f8=T g2 36. Tf5 g1=T 37. Lf8 Tgg5 38. Sg3 e4 39. Ld3 e3 40. 0-0 e2 41. Lb1 e1=T 42. Tc2 Te3 43. d5 Td7 44. d6 Tf7 45. d7+ Kb8 46. Dd6+ Ka8 47. Dc7 Sge7 48. d8=T+ Sc8 49. Tdd3 Thg8 50. h8=T Sd8 51. Th6 Lg2 52. Se4 Sb6 53. Sd6 Tf4 54. Sb7 Sc4 55. Thd6 T8g6 56. Tf3 Dg7 57. Te5 Sb2 58. Tbc4 Ld4 59. Sb4 Te1#
play all play one stop play next play all
https://www.thbrand.de/2021/12/25/59-zuege/

Am vierten Advent hatte ich noch gefragt, wie lange eurer Meinung nach der bestehende Längenrekord für (orthodoxe) Beweispartien wohl noch Bestand haben werde — und sechs Tage später präsentieren vier Autoren ihre Überbietung!! (OK, ich gebe zu: Als ich die Frage stellte, kannte ich schon die Antwort…)

Vor knapp fünf Jahren war der Versuch der ersten drei Autoren noch von Boris Tummes gekocht worden, nun hat er das Autorenteam verstärkt — und herausgekommen ist eine Beweispartie, die nun drei Halbzüge länger ist als der bisherige Rekord.

(diagram)

urz noch einmal zur Geschichte:
In den Jahren 1988/89 arbeiteten Pronkin und Frolkin elf Monate lang mit Hunderten von Positionen. Eine erste Rekordfassung (mit 58,0 Zügen) erschien in der Schwalbe im Juni 1989, eine kleine Korrektur (mit 57,5 Zügen), der bisherige Rekord, im Februar 1990. 2016 unternahm Frolkin, von Keym unterstützt, einen zweiten Versuch (Die Schwalbe , Februar 2017); doch wurde ihre Beweispartie (58,5 Züge) von Tummes als dualistisch nachgewiesen (Die Schwalbe, April 2018). In einem dritten Anlauf gelang Frolkin im Dezember 2021 gemeinsam mit Keym und Tummes der Durchbruch, der neue Rekord mit 59,0 Zügen.

Ich will euch gar nicht empfehlen, die Aufgabe selbst zu lösen — wer das dennoch machen will, wer noch weiter prüfen will, ist natürlich herzlich eingeladen!

Ansonsten: Spielt zuerst einmal die Lösung genüsslich durch, stellt euch für die nächsten Male im Prinzip die gleichen Fragen, wie ich sie für den alten Rekord vorgeschlagen hatte — und zum Schluss versucht einmal die Kniffe zu ergründen, mit denen den fantastischen Vier die Verlängerung gelang? Viel Spaß und anregende Beschäftigung wünsche ich euch dabei!

(solution)

Und den Vieren gilt mein herzlicher Glückwunsch zu dieser Großtat — und mein ebensolcher Dank, dass sie mir die Ehre zuteilwerden ließen, diese Superaufgabe hier im Blog urzudrucken und damit auf einen sicheren ersten Preis in einem beliebigen Informalturnier zu verzichten. Übrigens soll in der Schwalbe 2022 hierzu ein Aufsatz „aus erster Hand“ erscheinen, auf den ich schon sehr gespannt bin.
Cook: 1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 25. h4 d5 6. h5 d4 7. h6 d3 8. h7 dxc2 9. d4 a5 10. Lh6 c1=T 11. e4 Tc5 12. Se2 Th5 13. e5 c5 14. e6 Sc6 15. b8=T a4 16. Tb4 a3 17. Ta4 c4 18. b4 c3 19. b5 Da5 20. b6 g1=T 21. b7 Tg4 22. b8=T c2+ 23. T8b4 Lb7 24. d5 0-0-0 25. exf7 e5 26. d6 Kb8 27. d7 Lc5 28. f8=T Sge7 Tf3 a2 30. Tfa3 Sc8 31. f4 g5 32. f5 Tdg8 33. f6 e4 34. f7 e3 35. f8=T Tg6 36. Tf2 Tf4 37. Dd6+ Ka8 38. Sbc3 Thf8 39. Td1 T8f7 40. h8=T a1=D 41. Te8 c1=D 42. Lf8 g4 43. Sa2 g3 44. Dc7 g2 45. d8=T g1=T 46. T8d6 T1g5 47. Sg3 Dg7 48. Ld3 Ld4 49. 0-0 e2 50. Te5 e1=T 51. Lb1 Sd8 52. T1d3 Lg2 53. Se4 Dc6 54. Sc5 Te3 55. Tc2 Sb6 56. T1f3 Sc4 57. Sb7 Sb2 58. Tbc4 De8 59. Sb4 Te1# (Michail Kosulja)
James Malcom: We have a Christmas miracle: a new move length record! (2021-12-25)
Henrik Juel: Yes indeed
But maybe Mario or some other cook-finder will have the last word in a couple of years... (2021-12-26)
Henrik Juel: The cooking is not very surprising, but the speed of its appearance is (2021-12-31)
A.Buchanan: Was any shorter version of this (but greater than 57.5) sound? (2022-04-21)
more ...
comment
Keywords: Move Length Record, Aristocrat, Promotion (TD x12), Castling, Unique Proof Game, Non-standard material (TTTTTTddtttt), konsekutive Umwandlungen 2 (dd)
Genre: Retro
FEN: k2nqB2/1NQ2rq1/3R2r1/q3R1rr/RNRb1r2/R2R1R2/1nR3b1/1B2r1K1
Input: James Malcom, 2021-12-25
Last update: A.Buchanan, 2022-04-21 more...
38 - P1399601
Friedrich Burchard
Friedrich Hariuc

feenschach 33, p. 22, 4/1976
P1399601
(10+10)
BP in 48.0
1. e4 f5 2. e5 Sf6 3. exf6 e5 4. g4 e4 5. Se2 e3 6. Sg3 e2 7. h4 f4 8. h5 fxg3 9. h6 g5 10. Th4 gxh4 11. g5 g2 12. g6 Lg7 13. hxg7 g1=D 14. f4 h3 15. f5 h2 16. b4 a5 17. b5 a4 18. b6 a3 19. Lb2 Ta7 20. bxa7 axb2 21. a4 b5 22. a5 b4 23. a6 b3 24. c4 h1=D 25. c5 h5 26. c6 Lb7 27. cxb7 c5 28. d4 c4 29. d5 Sc6 30. dxc6 c3 31. c7 c2 32. c8=D c1=D 33. b8=D Dcc7 34. a8=D d5 35. a7 d4 36. Sc3 dxc3 37. Da6 c2 38. Da8-b7 c1=D 39. a8=D Dhd5 40. gxh8=D+ Kd7 41. g7 bxa1=D 42. g8=D b2 43. f7 b1=D 44. f8=D h4 45. f6 h3 46. f7 h2 47. Dfa3 h1=D 48. f8=D exf1=D+
play all play one stop play next play all
One of the shortest known ways to obtain 18 queens on the board

The challenge was presented in #31 http://problem64.beda.cz/silo/feenschach31_1975.pdf

#33: http://problem64.beda.cz/silo/feenschach33_1976.pdf
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)
more ...
comment
Keywords: Non-Unique Proof Game, Move Length Record, Aristocrat, Promotion (x16)
Genre: Retro
FEN: QQ1q1QQQ/1Qqk4/Q7/3q4/8/Q7/8/qqqQKqqq
Input: James Malcom, 2022-03-03
Last update: A.Buchanan, 2022-03-05 more...
39 - P1400086
Alain Brobecker
R587 The Problemist 2022/03
Dedicated to Mario Richter
P1400086
(2+4) C+
Add all remaining units for a legal position with no unit attacking an enemy unit.
We must have one WP and one BP per column, the BPs being above the WPs since no capture occurred.
On the c column the WP cannot be on c2, where it would attack the square d3 where a black shield would be needed
to protect from BQe4, and BP cannot be on c7 to c5, thus we have WPc3 and BPc4.
This implies that on column b we have BPb3 and WPb2, then due to BPb3 the only possibility on
column a is WPa3 and BPa4.
Now let us look at the shield needed to protect WRb7 from the attack of BQ e4: a black piece on c6 is not
possible, so we must have a black piece on d5. It cannot be a BN which would attack WQb6 or a BB which
still would attack WRb7, and the BK and BRs already are elsewhere, so we have BPd5. We then deduce that
we have WPd2, and this forces WBc1 which has not moved from the game.
We need another shield to protect BPb3 from the attack of WQb6. Now that WBb4 is no more possible since this
bishop is still home, the only possibility is WNb5.
We cannot have a black piece on e3, hence no white piece on e2 and from this we deduce that we have
WPd6 and BPd7. The only possible shield to protect WPe6 from the attack of BQe4 is BNe5 (BBe5 would attack WPc3).
Now we also need a shield on c7 to protect BPd7 from the attack of WRb7, and the only possibility is WKc7.
On the f column we have WPf2 which is the only possibility.
More difficult to see, the only possibility for light squared WB is WBh5. To see this we must acknowledge
that g2 will contain a black piece as a shield and that other squares are attacked and no shield will help:
WBb1 is not possible because no shield can be put in-between it and BQe4, and WBe8 is not possible
since no B piece can be placed in b8-d8 as a shield.
Let's suppose that we have WPh4, then two black shields are needed on on g2 and h3 to
protects WPf2 and WPh4 from BRh2, but one of this shield would be the light squared BB
and the other one would be the remaining BN which would attack on of the WPs.
Thus our hypothesis is wrong, and we have WPh6 then BPh7.
We deduce then that we have BPg5 then WPg3.
What we said about the black shields on g2 and h3 (to protect WBh5 this time)
still holds, but this time we have a possibility which is BNg2 and BBh3.
BBf6 is the only possible square for dark squared BB. Thus we have BPf5.
WNd1 is the only possible square for the remaining WN.
Last we have two possibilities for the remaining WR, namely a1 and f1.
But since WPa3, WPb2, WPd2, WBc1 forms a well know retro-analytical cage
from which the WR cannot have escaped, we know that we have WRa1.
r6k/1RK1p2p/1Q2Pb1P/1N1pnppB/p1p1q3/PpP3Pb/1P1P1Pnr/R1BN4
play all play one stop play next play all
Alain Brobecker: The dedication was forgotten in the magazine! (2022-03-28)
comment
Keywords: Construction task, Add pieces, Aristocrat, Miniature
Genre: Retro
Computer test: Verified with homebrew program: http://abrobecker.free.fr/tools/bndrnk.zip
FEN: r6k/1R6/1Q6/8/4q3/8/7r/8
Input: Alain Brobecker, 2022-03-28
Last update: Alain Brobecker, 2023-06-16 more...
40 - P1401711
Andrew Buchanan
OP008 The Hopper Magazine I01 24/12/2021
"Ak ja, retten, retten; hvad hjælper det, at du har retten, når du ikke har nogen magt?"
P1401711
(3+3) C+
h#2.5 (2 solutions)
Position after Black's 5,696th move
1. ... Se6 2. Th2 Ta8 3. Th7 Txe8#
1. ... Txa2 2. Lg6 Tg2 3. Lh7 Sf7#
not 1. ... 0-0-0 2. Lg6 Tg1 3. Lh7 Sf7#?? (game just ended by 50M)
play all play one stop play next play all
A full solution is really too big for PDB, but it is available at https://www.thehoppermagazine.com/AA084
Henrik Juel: solutions
1...Sg5-e6 2.Ra2-h2 Ra1-a8 3.Rh2-h7 Ra8*e8 #
1...Ra1*a2 2.Be8-g6 Ra2-g2 3.Bg6-h7 Sg5-f7 #
not 1...0-0-0? 2.Be8-g6 Rd1-g1 3.Bg6-h7 Sg5-f7 #
because White has lost his right to castle, as Andrew will explain, I hope... (2023-07-29)
A.Buchanan: White has not necessarily lost the right to castle, but if he can castle then the 50M rule triggers before the mate can be executed. It is pretty complicated, sorry. (2023-07-29)
A.Buchanan: We don't do mottoes much these days. Mrs Baird was a big fan. On page 301 of the July 1916 Chess Amateur P.H. Williams wrote:
"I think it was Mrs Baird who did more to search Shakespeare for accidental (or deliberate) reference to chess, since all her retractors had Shakespearean mottoes, and her knowledge of the Avonian bard was obviously extensive. Her example was followed by other composers of retractors, who considered such positions would be incomplete without some reference to the poet."
But there are other great playwrights, and Asteroid 5696 was named after one such, whose bitter quotation accurately states this problem's theme. (2023-07-31)
Henrik Juel: The citation is by danish philosopher Søren Kierkegaard (1813-1855) and means something like
Oh yes, to be right, to be right; it does not help much that you are right, when you have no power. (2023-07-31)
Henrik Juel: Asteroid 5696 is named Ibsen after the norwegian playwright Henrik Ibsen (1828-1906), who must have borrowed the citation from Søren Kierkegaard (2023-07-31)
A.Buchanan: Thanks for this Henrik - I resolved the question here: https://philosophy.stackexchange.com/questions/101229/did-ibsen-originate-this-statement
Beyond the castling try, the other innovation here is in the solution beginning 1...Se6. Castling convention and 50M I think are trying to combine by Retro Strategy (being optimistic about 50M rights like we are with castling, rather than pessimistic like we are with ep). (2023-08-04)
more ...
comment
Keywords: Aristocrat, Miniature, 50 move rule, Castling, Exchange of roles (T/S, Guard/Mate), Chumakov theme (l/t, simplified), Retro Strategy (RS), Model mate (2), Constrained problem
Genre: h#, Retro
Computer test: HC+ Popeye 4.61 and analysis
FEN: 4b2k/8/8/6N1/8/8/r7/R3K3
Reprints: AA084 The Hopper Magazine I04 13/07/2023
Input: A.Buchanan, 2022-06-09
Last update: A.Buchanan, 2023-08-27 more...
Show statistic for complete result. Show search result faster by using ids.

https://pdb.dieschwalbe.de/search.jsp?expression=COMMENTDATE%3E%3D20200919+AND+G%3D%27Retro%27+AND+K%3D%27Aristokrat%27

The problems of this query have been registered by the following contributors:

Gerd Wilts (18)
Felber, Volker (3)
Frank Müller (1)
Zuncke/Bruder (5)
A.Buchanan (6)
James Malcom (3)
Alfred Pfeiffer (1)
fs/hg (1)
Mario Richter (1)
Alain Brobecker (1)