Die Schwalbe

54 problem(s) found in 3008 milliseconds (displaying 54 problem(s)). [COMMENTDATE>=20200919 AND NOT K='Hilfsrückzüger' AND K='Rochade' AND A='Buchanan, Andrew'] [download as LaTeX]

1 - P1001038
Andrew Buchanan
4v Retros mailing list 21/01/2001
P1001038
(14+1) C+
Last move?
#2
1. 0-0 Kxe2 2. Te1#
R: 1. Ke4-e3
play all play one stop play next play all
Die vorherige Stellung war noch nicht tot, wenn Weiß noch rochieren darf.
AB: First proof of "can castle", without recourse to conventions. (2009-11-22)
A.Buchanan: deadpos doesn't understand about retro logic yet, so does not eliminate R: 1. Ke4xLSBe3? (2022-11-13)
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Keywords: Dead Position, Castling, Rex solus (s), Obvious promotion (L), Last Move?, Type B
Genre: Retro, 2#
Computer test: HC+ Forward Popeye 4.79 DP deadpos
FEN: 8/7Q/8/4BB2/2PP1P2/3NkN2/PP2P1P1/4K2R
Reprints: 13 idee & form 156, p. 5284, 10/2022
Input: Gerd Wilts, 2001-01-25
Last update: A.Buchanan, 2023-12-27 more...
2 - P1228018
Enzo Minerva
Andrew Buchanan

Introduction to Proof Games 01/2010
EM, version AB
P1228018
(14+14) C+
Proof game in 9.0
1. e4 f5 2. Lb5 f4 3. Se2 f3 4. 0-0 fxe2 5. e5 exf1=L 6. Dg4 Lc4 7. d3 Kf7 8. Dxc4+ d5 9. exd6ep+ Le6
play all play one stop play next play all
Shortest known proof game showing Valladao-Monteiro (after 8.5 moves - the extra half-move is to move beyond the check, and is the only move which preserves uniqueness of the PG).
Composed for http://abrobecker.free.fr/chess/IntroductionToPGs.pdf
>>> Agreed with Enzo Minerva that this is EM v AB: 24-Dec-2014. (Original is at P1284755.)
Kevin Begley: Partially anticipated, by Enzo Minerva, Best Problems 2005 (which shows Valladao-Monteiro in as many moves, based upon the same idea). (2014-03-01)
A.Buchanan: Thanks for highlighting this, Kevin. I had searched PDB for prior art before composing this one, but Enzo's problem was (and still is) absent. I feel that my little composition does add something more. In mine, the identity-defining Ceriani-Frolkin bishop move is not a capture. And WQ has potentially three routes to its final square, including the CF promotion square, but the two duals are eliminated by the waiting move d3. So, is Enzo still active? I am thinking this partial anticipation probably a case of "AB after EM" but if Enzo is still around I would like to discuss with him out of courtesy. (2014-05-01)
Kevin Begley: Andrew, at best, I see yours as a version. (2014-05-01)
Kevin Begley: Compare to 'P1284755'. Clearly Andrew's version is better (and not only because of the extra move avoiding check in diagram -- which may be forgiven in a proofgame aiming specifically for brevity), however thematically, they are nearly indistinguishable. I leave it for Andrew and Enzo to collaboratively determine the proper credit here. (2014-05-01)
A.Buchanan: Oh for Pete's sake... there's *another*, now I look in WinChloe:
Alexeï GASPARYAN Oakham PG Tourney,
The Problemist Supplement 2009-10
1° Mention d'Honneur.
rnb2rk1/pp1p1ppp/3p4/2q5/1b6/3p4/PPP1PKPP/RNBQ1BNR
PG in 9.0
1.f3 e5 2.f4 Bb4 3.f5 Ne7 4.f6 00 5.f×e7 e4 6.e8=N Qg5 7.Nd6 c×d6 8.Kf2 Qc5+ 9.d4 e×d3ep+ (C+)
Now the date in WinChloe is wrong: what counts is the closing date for the tournament, 31-12-2009 (although the judging was only held in 07-2010, and publication was in 11-2010). Mine was published in 01-2010 (composed on 10-01-2010. I think I fold at this point, and allow Messrs. Minerva & Gasparan to duke it out, if they care. (2014-05-04)
A.Buchanan: @Kevin: and on the subject of versioning. Do you have a link to anything that gives guidelines to relative attribution. The Codex is sketchy (as usual), and I don't know where else to look. (2014-05-04)
Henrik Juel: On versioning:
When inspired by a published problem by AA to improve it, I would write 'hj after AA' if my contribution is large and 'AA, version by hj' is it is small. Of course, 'improve', 'large', and 'small' are not well defined, so it is up to the improver and the editor what to choose, and up to the judge whether an award is warranted.
In the Minerva-Gasparyan-Buchanan case the later authors surely were not inspired by the first, so here I would suggest the following possibilities: anticipated, partially anticipated, and not anticipated, again leaving the final verdict to the judge (2014-05-04)
A.Buchanan: I don't see any fundamental difference between accidental and deliberate partial anticipation. Ultimately the choice is between labeling the problem as "A,version", "A,version B" or "B, after A". I am totally ok with whatever Minerva/Gasparyan eventually determine. However, I don't think that PDB supports "A, version B" currently. (2014-05-05)
A.Buchanan: Not heard anything from Messrs Minerva or Gasparyan. I should rephrase my earlier statement as: "I don't see any fundamental difference between accidental partial anticipation, and acknowledged deliberate versioning, in terms of the set of possible final outcomes." (2014-12-24)
A.Buchanan: Resolved with Enzo :D! (See above!) (2014-12-24)
A.Buchanan: Resolved with Alexey in Facebook yesterday :D! AB: "I would like to ask you: are you ok with the current attribution of my problem?" AG: "Yes I agree." So there we are. Maybe EM & AG will conduct diplomatic negotiations at some point, but that's not my concern :) (2021-10-05)
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Keywords: Valladao Task (swwk), Unique Proof Game, Ceriani-Frolkin Theme (l), Prentos Theme (l), En passant, Castling, Promotion (l)
Genre: Retro
Computer test: Euclide 0.99
FEN: rn1q1bnr/ppp1pkpp/3Pb3/1B6/2Q5/3P4/PPP2PPP/RNB3K1
Reprints: 11 Introduction to Proof Games 03/2010
Input: Alain Brobecker, 2011-12-26
Last update: A.Buchanan, 2021-05-26 more...
3 - P1370911
James Malcom
Andrew Buchanan

(4) MatPlus.net Forum Retro/Math 21/12/2019
P1370911
(12+14)
PG in 12.5
(-:
1. e4 d5 2. e5 Dd6 3. exd6 Kd7 4. dxe7 Kc6 5. Lb5+ Kxb5 6. c4+ Kxc4 7. e8=T Kd3 8. Df3+ Kc2 9. d3 Lh3 10. Ld2 Lxg2 11. Lb4 Lxh1 12. Sc3 Lg2 13. 0-0-0-0-0-0#
play all play one stop play next play all
http://matplus.net/start.php?px=1609818957&app=forum&act=posts&fid=xshowr&tid=2402&pid=20379#n20379
Objective: Staugaard (Pam-Krabbé) castling as mating move.
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Keywords: Unique Proof Game, Staugaard castling, Joke, Prenix, Promotion (T), Castling as mating move, Superseded by (P1385595)
Genre: Retro, Fairies
Computer test: C+ Natch 3.1 has no solutions in 12.5 moves & 1 solution for first 12.0 moves. (H.Juel)
FEN: rn3bnr/ppp2ppp/8/3p4/1B6/2NPKQ2/PPk1RPbP/R5N1
Input: A.Buchanan, 2019-12-23
Last update: James Malcom, 2022-02-26 more...
4 - P1380852
James Malcom
Andrew Buchanan

MatPlus.net Forum 12/10/2020
after Josef Cumpe
P1380852
(1+7)
Last two moves?
(-:
R: 1. 0-0-0+ a7-a8=sT
play all play one stop play next play all
See P1234039 and P1375777
The joke here is that pawns may promote to enemy officers (but not to pawns or kings)
Henrik Juel: R: 1... 0-0-0+ 2.a7-a8=sT! (2020-10-12)
A.Buchanan: Maybe this is a moderate joke where we allow promotion to Bl officers, while son-of-P1375777 can be the extreme joke where promotion to any Bl unit is allowed (i.e. pawn & king too), including in the history of the game. What would Josef Cumpe think? :-) He and I are both dressed as clerics in out chesscomposers' blogspot pics: http://chesscomposers.blogspot.com/2012/08/august-16th.html. Perhaps he was a real one though? (2020-10-13)
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Keywords: Last Moves?, Joke promotion (t), Rex solus, Type C, Castling in the retro play, Joke, Promotion in the retro play (t), Castling (sg)
Genre: Retro
FEN: 2kr2K1/1p1p1npr/8/8/8/8/8/8
Input: A.Buchanan, 2020-10-12
Last update: A.Buchanan, 2023-08-15 more...
5 - P1380882
James Malcom
Andrew Buchanan

PDB Website 14/10/2020
after Josef Cumpe
P1380882
(2+7)
Last two moves?
(-:
R: 1. ... 0-0-0+ 2. a7-a8=sT
play all play one stop play next play all
See P1234039, P1375777 and P1380852.
The joke here is that pawns may promote to *any* unit (friend or enemy; officer, king or pawns).
Henrik Juel: R: 1... 0-0-0+ 2.a7-a8=sT
not 2.e7-e8=sK, because then sTa8 would have moved, and castling not allowed (2020-10-14)
A.Buchanan: Exactly, Henrik. Also: sB on 7th rank could retract to 8th rank, so we need sT instead (2020-10-14)
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Keywords: Last Moves? (2), Type C, Castling in the retro play, Non-standard material (tt), Joke, Joke promotion (t), Promotion in the retro play (t), Minimal, Castling (sg)
Genre: Retro
FEN: 2kr3K/1r1r1qrR/7p/8/8/8/8/8
Input: A.Buchanan, 2020-10-14
Last update: A.Buchanan, 2023-08-15 more...
6 - P1382808
Ronald Turnbull
Andrew Buchanan

PDB Website 20/01/2012
RT, correction AB
P1382808
(4+12)
h#3
AP
PRA
1. bxc3ep 0-0! (for AP reasons, not 1...Kf2?/Th2? etc) 2. Ta1 Txa1 3. Kc4 Txa4#
1. fxe3ep 0-0! (for AP reasons, not 1...Tf1?/Txh3? etc) b2 Txf3 3. Tc3 Tf4#
play all play one stop play next play all
For AP as for anything else, the default meta-convention is PRA before RS. Here we use AP to lock down wK & wTh1, so the last move was R: 1. c2-c4 or 1. e2-e4. There is a different h#3 in either case, beginning with ep and then 0-0.
Chessically corrects P1012059 following discussions. It's doubtful that AP logic works as simplistically described here, so this may still be unsound logically. Nevertheless, might as well fix the chess!
See P1399112, where the two parts each prove that one side of White castling rights remain. If this is correct, and only *one* part is required per castling, this implies that this Turnbull-Buchanan problem doesn’t work. For one part we have solution c_S and tries c_T1 & c_T2. In the other part, solution e_S and tries e_T1 & e_T2. Any of 5 combinations work:
c_S + e_S
c_S + e_T1
c_S + e_T2
c_T1 + e_S
c_T2 + e_S
because they all confirm that White retains castling rights.
Classify this problem as Golden Age because it’s on the wrong side of the evolving standard.
A.Buchanan: Let ??? Indicate respectively that w00, c ep & e ep are ok. Then YYN, YNY, NYN, NNY, NNN are the contenders.
Under PRA we reduce to YYN, YNY & NNN but the last has no solution so not the right paradigm.
Under SPRA with AP we reduce to YYN, YNY. Each considered as a separate part has kind of AP h#3, but I don’t understand how consolidation would take place over PRA anyway
Under RS with AP, we have 2 solutions assuming again that no consolidation. (2022-03-23)
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Keywords: a posteriori (AP) (Type Petrovic - cee), En passant as key (2), Castling (wk), Retro Strategy (RS), Golden Age (AP unconsolidated)
Genre: h#, Retro
Computer test: Forward logic sound by Popeye v4.85 However, seems that AP logic is not sound
FEN: 8/8/8/1nr1n3/ppPkPp2/rp1p1p1p/8/4K2R
Input: A.Buchanan, 2020-12-08
Last update: A.Buchanan, 2023-04-06 more...
7 - P1382819
Vladimir Korolkov
Andrew Buchanan

PDB Website 09/12/2020
VK, version AB
P1382819
(12+14) C+
h#3
1. 0-0 Tf1 2. Txf2 Txf2 3. Kh8 Tf8#
For parity reasons, not 1...0-0?
play all play one stop play next play all
Corrects (with a little more functionality) P0001361
Henrik Juel: How does one find the parity of the white moves, with DLSS missing? (2020-12-09)
Henrik Juel: Never mind
If White can castle, then last move was e2-e3, so we know where the missing white men were captured, and the parity is easily found (2020-12-09)
Henrik Juel: Suppose (for contradiction) that both sides may castle
Black has the move, so last move was e2-e3, and [Dd1,Lf1] were captured at home, and [Sb1,Sg1] were captured on e6,d5
The number of white and black moves in the game leading to the diagram are both even, so White should have the move
Conclusion: the castlings are mutually exclusive
In the solution Black must castle to get his king to h8, so White cannot get his Th1 to f1 by castling (2020-12-09)
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Keywords: Parity Argument, Castling (wksk), Castling, mutual exclusive
Genre: h#, Retro
Computer test: C+ Popeye v4.85 + thinking
FEN: 2b1k2r/rpppp1pp/p2n4/3p4/8/4P3/PPPP1PPP/RnB1K2R
Input: A.Buchanan, 2020-12-09
Last update: A.Buchanan, 2020-12-09 more...
8 - P1382903
Andrey Frolkin
Andrew Buchanan

2 Die Schwalbe 360-1, p. 737, 12/2020
P1382903
(14+12)
Erster Zug des wTf6?
R: 1. Tf1xBf6! b6xSa5 2. 0-0! a7xSb6 3. Lf1-e2 Kd4-e5,Kf4-e5 4. e2-e3+
play all play one stop play next play all
James Malcom: How does this work exactly? What forbids the rook from just making some random tempi move in a game that leads to this position? (2020-12-12)
Mario Richter: James, think of time pressure. In the diagram, Black has only two retractions (a7xSb6xSa5). The only way to unlock the position is the retraction of e2-e3.
Little hint: castling is considered as a king m,opve ... (2020-12-12)
Henrik Juel: By now there are so many clues revealed for this fine retro that I dare to give a retroplay despite the Byzantine dating, in this case indicating an ongoing solving competition
R: 1.Tf1xPf6 b6xSa5 2.0-0 a7xSb6 3.Lf1-e2 Kd4,Kf4 4.e2-e3+ etc.
Incidentally, TxP is not the first move, but the last... (2020-12-12)
Henrik Juel: I missed the from square in the retraction by the black king, sorry
3... Kd4-e5,Kf4-e5 (2020-12-12)
A.Buchanan: Ha, there is no solving competition for these either. But it's to avoid Gerd's solving competition protection algorithm picking up false positives (2020-12-12)
A.Buchanan: TxP happens to be the last move, but it's also the first effective move of the rook, as it is considered to be a *passenger* in the castling, and not to have moved yet. Otherwise can't get first move of a rook fixed if it capturing (except possibly by DP logic). See the explanatory article: https://www.dieschwalbe.de/download/artikel/Passenger_Rooks.pdf (2020-12-12)
A.Buchanan: Your solution is completely correct, Henrik! (2020-12-12)
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Keywords: Economy record (First move), Type A, First Move? (TxB), Castling in the retro play (wk), Non-standard material (l), Castling (wk)
Genre: Retro
FEN: 5b1n/1p2prBP/P2PrRQb/p2pk1pR/7p/3PP3/1P2B1PP/6K1
Reprints: 2 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
9 - P1382904
Andrey Frolkin
Andrew Buchanan

3 Die Schwalbe 360-1, p. 737, 12/2020
P1382904
(14+10)
Erster Zug des wTf6?
R: 1. Lg2-f3 b4-b3 2. Tf1xSf6! b5-b4 3. 0-0! b6-b5 4. Lf1-g2 Kf4-g5,Kh4-g5 5. g2-g3+
play all play one stop play next play all
Henrik Juel: Oh, I was confused by the LLLLl, which should be TLLLLl, I believe
R: 1.Lg2-f3 b4-b3 2.Tf1xSf6! b5-b4 3.0-0 b6-b5 4.Lf1-g2 Kf4-g5,Kh4-g5 5.g2-g3+ (2020-12-12)
A.Buchanan: Thanks for the catch. I copied the diagrams straight from the article FEN, so should be clean of transcription errors, but then I put in the non-standard material field by hand & eye, so could be other errors as here. (2020-12-12)
A.Buchanan: Your move sequence is again correct! :D (2020-12-12)
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Keywords: Economy record (First move), Type A, First Move? (TxS), Castling in the retro play (wk), Non-standard material (TLLLLl), Castling (wk)
Genre: Retro
FEN: 3bRBB1/2ppBQRp/3ppRBb/6kB/6p1/1p3BP1/4P2P/6K1
Reprints: 3 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
10 - P1382906
Andrey Frolkin
Andrew Buchanan

4 Die Schwalbe 360-1, p. 738, 12/2020
P1382906
(14+9)
Erster Zug des wTf8?
R: 1. Tf1xLf8! e4-e3 2. 0-0! e5-e4 3. Lf1-g2 e6-e5 4. g2xBh3 h4-h3 and e.g. 5. d4-d5 h5-h4 6. Le4-c6 h6-h5 7. c7-c8=L! h7-h6 8. c6-c7 c7xLb6
play all play one stop play next play all
Henrik Juel: Good motivation for TxL
R: 1.Tf1xLf8! e4-e3 2.0-0 e5-e4 3.Lf1-g2 e6-e5 4.g2xPh3 h4-h3 and e.g.
5.d4-d5 h5-h4 6.Le4-c6 h6-h5 7.c7-c8=L! h7-h6 8.c6-c7 c7xLb6
f7xTg8=L happened early (2020-12-12)
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Keywords: Economy record (First move), Type A, First Move? (TxL), Castling in the retro play (wk), Non-standard material (LL), Castling (wk)
Genre: Retro
FEN: k1B2RQ1/Pp1pp1p1/rpB3N1/pN1P4/8/4p2P/2P1P1BP/6K1
Reprints: 4 Die Schwalbe Online 12/2020
www.thbrand.de 13/12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
11 - P1382907
Andrey Frolkin
Andrew Buchanan

5 Die Schwalbe 360-1, p. 738, 12/2020
P1382907
(13+12)
Erster Zug des wTf6?
R: 1. Tf1xTf6 c3-c2 2. Lf3-a8 c4-c3 3. 0-0 c5-c4 4. Lg2-f3 c6-c5 5. Lf1-g2 Kf4-g5,Kh4-g5 6. g2-g3+
play all play one stop play next play all
Hans-Jürgen Manthey: 1. Lg2-a8 c3-c2 2. Tf1xTf6 c4-c3 3. O-O ??? (Rochade nicht möglich wegen sTf6 !)

mögliche Lösung:
1. Tf1xTf6 c3-c2 2. Lf3-a8 c4-c3 3. O-O c5-c4 4. Lg2-f3 c6-c5 5. Lf1-g2 Kf4-g5 6. g2-g3+ Sg5-h7 7. Ld3-g6 Se4-g5 8. Th7-g7 Dg6-f7 9. f7-f8L Tf5-f6 10. Le5-h8 Lf8-h6 11. Lh4-e7 Dg5-g6 12. La7-e5 Tf6-f5 13. Lb8-a7 Th6-f6 14. Lf6-d8 Sc5-e4 15. Lb2-f6 Dd8-g5 16. Lf2-h4 Kg5-f4 17. f6-f7 Sa6-c5 18. Te7-h7 Th8-h6 19. f5-f6 Kh6-g5 20. La3-b2 Kg7-h6 21. Lf7-e8+ Kf6-g7 22. Lc1-a3 Kg7-f6 23. b7-b8L h7-h5 24. La7-f2 Kf6-g7 25. Lb8-a7 Kg7-f6 26. b6-b7 Kf6-g7 27. b7-b8L Kg7-f6 28. Te8-e7 Df6-d8 29. Ta8-e8 g5-g4 30. Le8-f7 f7xSe6 31. Sf4-e6+ Sb8-a6 32. Ta1-a8 Dd8-f6 33. e7-e8L Kf6-g7 34. e6-e7 Ke7-f6 35. b5-b6 g6-g5 36. b6-b7 g7-g6 37. c4xLb5 La6-b5 38. c2-c4 Lc8-a6 39. La6-d3 Ke8-e7 40. Lb7-a6 Ke7-e8 41. La8-b7 Ke8-e7 42. a7-a8L Ke7-e8 43. d5xTe6 Te3-e6 44. a6-a7 Ke8-e7 45. a5-a6 Ke7-e8 46. a4-a5 Ke8-e7 47. a2-a4 Ta3-e3 48. Sh3-f4 Ta8-a3 49. Sg1-h3 b7xSc6 50. Sa7-c6 Sc6-b8 51. Sb5xa7 e7xDd6 52. Dh6-d6 Sb8-c6 53. Dd2-h6 Sc6-b8 54. Dd1-d2 Sb8-c6 55. f4-f5 Sc6-b8 56. f2-f4 Sb8-c6 57. d4-d5 Sc6-b8 58. d2-d4 Sb8-c6 59. Sc3-b5 Sc6-b8 60. Sb1-c3 Sb8-c6 61. b5-b6 Sc6-b8 62. b4-b5 Sb8-c6 63. b2-b4 (2020-12-14)
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Keywords: Economy record (First move), Type A, First Move? (TxT), Castling in the retro play (wk), Non-standard material (LLLLL), Castling (wk)
Genre: Retro
FEN: B2BBBnB/2ppBqRn/3ppRBb/6kp/6p1/6P1/2p1P2P/6K1
Reprints: 5 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
12 - P1382908
Andrey Frolkin
Andrew Buchanan

6 Die Schwalbe 360-1, p. 738, 12/2020
P1382908
(11+14)
Erster Zug des wTf6?
R: 1. Tf1xDf6 b3xLc2 2. Le4-c2 and e.g. 2. ... c5-c4 3. Lf3-e4 c6-c5 4. 0-0 b4-b3 5. Lg2-f3 b5-b4 6. Lf1-g2 Kf4-g5 7. g2-g3+
play all play one stop play next play all
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Keywords: Economy record (First move), Type A, First Move? (TxD), Castling in the retro play (wk), Non-standard material (L), Castling (wk)
Genre: Retro
FEN: 3BBn2/2pRBrPn/3pQRrb/3pp1kp/2p3p1/6P1/2p1P2P/6K1
Reprints: 6 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
13 - P1382910
Andrey Frolkin
Andrew Buchanan

8 Die Schwalbe 360-1, p. 740, 12/2020
P1382910
(16+6)
Erster Zug des wTf3?
R: 1. Tf1xBf3+! f4-f3 2. f3xBe4+ e5-e4 3. 0-0! Kg2-g3
play all play one stop play next play all
Henrik Juel: White captured TxPf3+, axbxcxd, bxcxd, cxd, fxPe, g5xh6, and h6xg7-g8=L
R: 1.Tf1xPf3+ f4-f3 2,f3xPe4+ e5-e4 3.0-0 Kg2-g3 (2020-12-12)
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Keywords: Economy record (First move), Type C, First Move? (TxB), Castling in the retro play (wk), Non-standard material (DTLL), Castling (wk)
Genre: Retro
FEN: 3N4/ppp4P/4NBpB/5BQp/4P1BR/R3QRk1/3PP3/6K1
Reprints: 8 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
14 - P1382911
Andrey Frolkin
Andrew Buchanan

9 Die Schwalbe 360-1, p. 740, 12/2020
P1382911
(12+6)
Erster Zug des wTd1?
R: 1. Tf1xSd1+! Sc3-d1 2. 0-0+!
play all play one stop play next play all
Henrik Juel: Black has played c3/a3xLb2-b1=T, earlier Kb4-a3-b2-b1, and still earlier Sb3xTa1
R: 1.Tf1xSd1+ Sc3-d1 2.0-0+ (2020-12-12)
Henrik Juel: A very impressive set of retros
Thanks for making them available, Andrew (2020-12-12)
A.Buchanan: Very welcome Henrik: thanks for your invaluable solving! (2020-12-13)
comment
Keywords: Economy record (First move), Type C, First Move? (TxS), Castling in the retro play (wk), Castling (wk)
Genre: Retro
FEN: N7/p1p5/8/8/8/PP6/qrPPPPPP/nNkR2K1
Reprints: 9 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
15 - P1382912
Andrey Frolkin
Andrew Buchanan

10 Die Schwalbe 360-1, p. 741, 12/2020
P1382912
(10+8)
Erster Zug des wTf8?
R: 1. Tf1xLf8+ & e.g. f4xSg3,f4x~g3 2. 0-0 e5xLf4,e5x~f4 3. Lf1-g2 d6xDe5,d6x~e5 4. g2xSh3,g2x~h3
and later White unpromotes via a7,c7&f7
play all play one stop play next play all
more ...
comment
Keywords: Economy record (First move), Type C, First Move? (TxL), Castling in the retro play (wk), Castling (wk)
Genre: Retro
FEN: R4R1k/1p1pp1pP/6pp/3N4/8/6pP/4P1BP/3B2K1
Reprints: 10 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
16 - P1382913
Andrey Frolkin
Andrew Buchanan

11 Die Schwalbe 360-1, p. 741, 12/2020
P1382913
(13+8)
First move of [wTh1]?
R: 1. ... g3xTf2+! 2. Tf1xTf2+! Tf3xTf2 (not 2.Tf1xSf2+?Sh1xTf2? because the second wT delivers illegal check) 3. 0-0! Dh2-h3 and e.g. 4. Tf1-f2 Lg1-e3 5. Sf2-d1 Ke5-f4 6. e3xBd4+
play all play one stop play next play all
Henrik Juel: R: 1... g3xTf2 2.Tf1xTf2 Tf3xTf2 3.0-0 Dh2-h3 and e.g.
4.Tf1-f2 Lg1-e3 5.Sf2-d1 Ke5-f4 6.e3xPd4+
The remaining capture by Black was f5xLg4
[Pa7] was captured by a white officer (2020-12-13)
comment
Keywords: Economy record (First move), Type C, First Move? (TxT), Castling in the retro play (wk), Castling (wk)
Genre: Retro
FEN: 8/1p5p/8/5PP1/3PNkpB/2PPb2q/P1pPPpQ1/3N2K1
Reprints: 11 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
17 - P1382914
Andrey Frolkin
Andrew Buchanan

12c Die Schwalbe 360-1, p. 741, 12/2020
P1382914
(16+8)
Erster Zug des wTf2?
R: 1. Tf1xDf2+ Dg3-f2+ 2. Lf2xBb6 b7-b6 3. 0-0! Dh2-g3
play all play one stop play next play all
Minor correction: sBd7->c6 wSb2->wL
Henrik Juel: Not R: 1.Tf1xDf2+ Dg3-f2+ 2.Lf2xPb6 b7-b6 3.0-0 Dh2-g3,
because White can no longer uncapture hxgxh
What was the intention? (2020-12-13)
A.Buchanan: Attempted repair to avoid accidentally retro-blocking c8 (2020-12-23)
Hans-Jürgen Manthey: mögliches Retrospiel: 1. Tf1xDf2# Dg3-f2 2. Lf2xb6+ b7-b6 3. O-O Dh2-g3 4. Se3-g2 Dg2-h2 5. Sc4-e3 Dh2-g2 6. Tg1-g4 Dg2-h2 7. Sa3-c4 Dh2-g2 8. g4-g5 Dg2-h2 9. Lb6-f2 Dh2-g2 10. Ld8-b6 Ke3-f3 11. d7-d8L Kd4-e3 12. Sc3-e2+ Kc5-d4 13. Le2-d1 Kd6-c5 14. Lf1-e2 Tf2-d2 15. Tg2-g1 Tf3-f2 16. Td2-g2 Se2-c1 17. Td1-d2 Te3-f3 18. Tb1-d1 Te6-e3 19. Lc1-b2 Th6-e6 20. f2-f4 Th8-h6 21. g2-g4 Sf4-e2 22. Se2-f3 Sd5-f4 23. Sg1-e2 Ke6-d6 24. Df4-h4 Ta8-h8 25. Da4xBf4 f5-f4 26. Da5-a4 Db8-h2 27. g4xTh5 h4-h3 28. b2-b3 Sb3-a1 29. Dd8xBa5 Sc5-b3 30. Df8-d8 a7-a5 31. Dh8xLf8 f7-f5 32. d6-d7 Kd7-e6 33. e5xBd6 Sf6-d5 34. Dh7-h8 Ke8-d7 35. De4-h7 Sg8-f6 36. Ta1-b1 Dd8-b8 37. Sb1-a3 Th8-h5 38. h3xLg4 h5-h4 39. h2-h3 Lc8-g4 40. De2-e4 h7-h5 41. e4-e5 c7-c6 42. d2-d3 Sa6-c5 43. Dd1-e2 d7-d6 46. e3-e4 Sb8-a6 47. e2-e3 (2020-12-25)
more ...
comment
Keywords: Economy record (First move), Type C, First Move? (TxD), Castling in the retro play (wk), Non-standard material (S), Castling (wk)
Genre: Retro
FEN: 8/4p1p1/1Bp5/6PP/5PRQ/1P1P1k1p/PBPrNRN1/n1nB2K1
Reprints: 12 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
18 - P1382915
Andrey Frolkin
Andrew Buchanan

13 Die Schwalbe 360-1, p. 741, 12/2020
P1382915
(15+10)
Erster Zug des wTf3?
R: 1. Tf1xDf3+! Sf2-h1 2. 0-0! Se4-f2 and e.g. 3. Sf2-h3 Lh3-g4 4. Lg4-h5 Th5-g5 5. g5-g6 Th6-h5 6. Lh5-g4
play all play one stop play next play all
more ...
comment
Keywords: First Move? (TxD), Type C, Castling in the retro play (wk), Non-standard material (t), Castling (wk)
Genre: Retro
FEN: 8/4p2p/6P1/5PrB/5pbb/1PPPkRRN/1PPr2Pr/2BQ2Kn
Reprints: 13 Die Schwalbe Online 12/2020
Input: A.Buchanan, 2020-12-12
Last update: A.Buchanan, 2023-08-15 more...
19 - P1385595
Andrew Buchanan
James Malcom
Hauke Reddmann
Michel Caillaud

MatPlus.net Forum 06/01/2021
in memory of Conrad Staugaard
P1385595
(14+13)
PG in 10.0
Staugaard castling
b) 1. d4 f5 2. Kd2 f4 3. Kd3 f3 4. Ke4 fxe2 5. Kf5 e1=T 6. De2 g5 7. Dxe7+ Sxe7+ 8. Kf6 Lg7+ 9. Kxg7 Sd5 10. Kxh8 0-0-0-0-0-0#
play all play one stop play next play all
Objective: Staugaard (Pam-Krabbé) castling as mating move.
Henrik Juel: solution
1. Bd2-d4 Bf7-f5 2. Ke1-d2 Bf5-f4 3. Kd2-d3 Bf4-f3
4. Kd3-e4 Bf3xe2 5. Ke4-f5 Be2-e1=T 6. Dd1-e2 Bg7-g5
7. De2xe7 Sg8xe7 8. Kf5-f6 Lf8-g7 9. Kf6xg7 Se7-d5
10. Kg7xh8 0-0-0-0-0-0#
First 9.5 moves are C+ Euclide 1.01
On behalf of the danish inventor of the looong castling, I thank for the dedication (2021-01-21)
James Malcom: After the 12.5 Andrew and I made, this turns out the fastest possible. 9.0 if you go non-unique. (2021-01-21)
A.Buchanan: Welcome, Henrik. Any idea what his initial "C." stands for? I couldn't find it online. (2021-01-22)
Henrik Juel: Unfortunately not, Andrew
In those days the first name was almost always abbreviated to an initial
Christian was a very common first name, but this was usually abbreviated to Chr.
So a wild guess is Carl, but it really could be anything starting with C
In a Skakbladet issue he is referred to as Direktør Staugaard, but this just means that he was in charge of a company (2021-01-22)
A.Buchanan: I have posted an English definition of the keyword. Please check if it suits. (2021-01-22)
Henrik Juel: Searching for direktør staugaard, randers (a danish city) yields
Conrad Staugaard (1852-1922)
so this is my best bet
Conrad Staugaard headed a bank in Randers, founded by him in 1891, but the CV in
http://historiskranders.dk/randers-biografier/
does not mention anything about playing chess or chess problems
Chess playing was very common in the middle class, so the biographer may not have found it worth mentioning (2021-01-22)
Henrik Juel: Your keyword definition seems fine,
except for the spelling of showcase... (2021-01-22)
A.Buchanan: Haha bingo: "Staugaard was a well-known and excellent chess-player, one of the many traits he had in common with Lewis Carroll". MMA SAM - Tidsskrift.dk. Googling for "Conrad Staugaard skak" brings up the pdf for Rama Sama. Please tell us what you make of it, Henrik :) In the mean time, I have updated the author info for him (2021-01-22)
Henrik Juel: Very good, Andrew
Ah, the joys of Google...
In the danish text there is not only your citation on chess, but also one on chess problems
There are also examples of Conrad's excentric behaviour, in line with him inventing the looong castling
That C. Staugaard might be Conrad's younger brother Carl (who surely also knew about chess) is ruled out by the fact that Carl emigrated to South America in 1901, because he experienced disappointments in his love live... (2021-01-22)
A.Buchanan: Yes it said he had lots of amazing concepts. The idea about the banner for his nursemaid to take his children for walks without getting her arms stretched is very funny. This is our man. He also seems to have been a good man, and an effective businessman. And loved enough by his friends for a 120 page book to have been commissioned in his memory. He is reminiscent of other children’s authors like Edward Lear, Dr Seuss, Heinrich Hoffmann... I’m so happy that this problem has brought him back to our awareness (2021-01-23)
comment
Keywords: Unique Proof Game, Staugaard castling, Prenix (t), Promotion (t), Castling as mating move, Economy record
Genre: Retro, Fairies
Computer test: HC+ the last move can only have been 0^6 discovering mate & the first 9.5 moves are C+ Euclide 1.01.
FEN: rnbq3K/ppppr2p/4k3/3n2p1/3P4/8/PPP2PPP/RNB2BNR
Input: A.Buchanan, 2021-01-21
Last update: Rainer Staudte, 2021-05-10 more...
20 - P1385597
Andrew Buchanan
MatPlus.net Forum 08/01/2021
P1385597
(14+14) C+
PG in 7.5
Staugaard castling
b) 1. e4 d5 2. Ld3 Lf5 3. exf5 Dd6 4. f6 Sd7 5. Lg6 0-0-0 6. fxe7 Dxh2 7. e8=T Dxh1 8. 0-0-0-0-0-0
play all play one stop play next play all
Popeye says there's no orthodox solution in 7.5, so it must be Staugaard. With castling as W8, there Popeye finds a unique solution for the first 7.0. Otherwise we can count both sides' moves, with e2-e4xLf5-f6xBe7-e8=T. If we R: 1. Ld3-g6 Dh7xTh8 2. 0^6, then Popeye says no solution, and there is no alternative White retraction. This is enough for me to say HC+.
Objective: Staugaard (Pam-Krabbé) + queenside castling.
more ...
comment
Keywords: Unique Proof Game, Staugaard castling, Castling (2), Prenix (T), Promotion (T)
Genre: Retro, Fairies
Computer test: HC+ Popeye v4.85 + argument in sol text
FEN: 2kr1bnr/pppn1ppp/6B1/3p4/8/4K3/PPPPRPP1/RNBQ2Nq
Input: A.Buchanan, 2021-01-21
Last update: Rainer Staudte, 2021-05-10 more...
21 - P1385598
Andrew Buchanan
MatPlus.net Forum 10/01/2021
P1385598
(14+14)
PG in 7.5
Staugaard castling
1. d4 e5 2. Lf4 exf4 3. Dd3 f3 4. Dxh7 fxe2 5. f4 g6 6. Kf2 e1=T 7. Dxh8 0-0-0-0-0-0 8. De5#
play all play one stop play next play all
Objective: Staugaard (Pam-Krabbé) king is mated.
Henrik Juel: The first 6.5 moves are C+ Euclide 1.01 (2021-05-08)
A.Buchanan: Thanks Henrik. In the advance of an engine supporting Staugaard, here is my purely HC+ proof of soundness. No orthodox solution so 6 Bl moves needed to Staugaard. Other Bl move was g7-g6 or h7xg6. bRh8 & other bPg/bPh never moved - captured by Wh raider(s). Only piece that could have captured wPe was bPe, so it captured twice, other prey being wB, which thus moved once, and could not have been the raider. 6 Wh moves now countable without raiding, so wQ raided, and took 4 moves. All Wh moves now accounted for, so bPe7-e5xf4-f3xe2-e1=T. wQ could only have exited on d file, as diagonal d1-h5 open too late. Thus wQ-d3xh7xh8-e5#. All moves are known, and jigsaw of them moves is unique, ensuring each side can always move. (2021-05-08)
A.Buchanan: I forgot to say that I think my manual proof, while watertight, is too complex to make the status of this problem HC+. I think HC+ is for where the H part is self-evident. (2021-05-08)
more ...
comment
Keywords: Unique Proof Game, Staugaard castling, Prenix (t), Promotion (t), Castling
Genre: Retro, Fairies
FEN: rnbq1bn1/pppprp2/4k1p1/4Q3/3P4/5P2/PPP2KPP/RN3BNR
Input: A.Buchanan, 2021-01-21
Last update: Rainer Staudte, 2021-05-10 more...
22 - P1385601
Andrew Buchanan
MatPlus.net Forum 16/01/2021
to Joost de Heer
P1385601
(12+15)
PG in 11.5
b) Is the position before the last black move a sound proof game in 10.5?
Staugaard castling
a) 1. e3 h6 2. Ld3 Th7 3. Lxh7 e6 4. Lf5 exf5 5. Sf3 f4 6. 0-0 fxe3 7. Se1 exd2 8. Df3 dxe1=T 9. Le3 b6 10. Sd2 b5 11. Lb6 0-0-0-0-0-0 12. Tfb1
b) No: 1. e3 h6 2. Ld3 Th7 3. Lxh7 e6 4. Lf5 exf5 5. Sf3 f4 6. 0-0 fxe3 7. Se1 exd2 8. Df3 and now d1=T 9. Le3 Txe1/b5/b5 10. Sd2/Sd2/Lb6 b5/Txe1/Txe1 11. Lb6/Lb6/Sd2 have no P-K castling rights.
play all play one stop play next play all
Objective: Play of Staugaard (Pam-Krabbé) castling makes unsound PG sound.
Henrik Juel: I see no castling paradox (2021-01-21)
A.Buchanan: I must complete the stipulation, sry (2021-01-22)
A.Buchanan: Not really paradox in the usual hidden/fake sense. Need a different term for the occasional idea that an earlier point in the proof game is not unique. (2021-01-22)
more ...
comment
Keywords: Unique Proof Game, Staugaard castling, Phoenix (t), Promotion (t), Castling (2)
Genre: Retro, Fairies
FEN: rnbq1bn1/p1pprpp1/1B2k2p/1p6/8/5Q2/PPPN1PPP/RR4K1
Input: A.Buchanan, 2021-01-21
Last update: A.Buchanan, 2021-05-09 more...
23 - P1386410
Andrew Buchanan
chess.stackexchange.com 11/02/2021
P1386410
(16+16)
Find a diagram which can recur a maximum number of times, such that it also has a unique KBP (shortest proof game) to its first occurrence.
a) with 3-fold repetition & 50-move rules
b) with 5-fold repetition & 75-move rules
a) e.g. 1. a4 e5 2. a5 e4 3. a6 Sxa6 4. f4
b) e.g. 1. e3 a5 2. La6 e6 3. Se2
play all play one stop play next play all
a) 22 occurrences possible, with 44.5 moves, so no issue with 50-move rule even if it were mandatory.
b) 37 occurrences possible, with 74.0 moves + 0.5 for 3. Se2 in proof game.
The theoretical maximum of 42 is impossible, because it would take 84.5 moves, breaching the mandatory 75-move rule.
Other shortest unique SPGs are possible, but need:
(1) both sides have at least 2 of K,R & R able to move.
(2) both sides must have officer to triangulate.
(3) (for player on the move) triangulating officer must be B or Q.
(4) (for 3+50 case only) e.p. set up.
A.Buchanan: Without German KBP in the stip the animation won't work (2021-02-12)
comment
Keywords: Construction task (non-unique), Synthetic problem, 50 move rule, 75 move rule, Draw by repetition, En passant, Castling, Homebase
Genre: Retro
FEN: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
Input: A.Buchanan, 2021-02-12
Last update: A.Buchanan, 2024-03-19 more...
24 - P1389375
Andrew Buchanan
MatPlus.net Forum 22/01/2021
P1389375
(14+14) C+
PG in 7.0
Staugaard castling
1. g3 e6 2. Lg2 e5 3. Lxb7 e4 4. Sf3 exf3 5. 0-0 fxe2 6. Lxa8 e1=T 7. Lg2 0-0-0-0-0-0
play all play one stop play next play all
Objective: fastest Staugaard (Pam-Krabbé) + another castling (happens to be kside)
A.Buchanan: Now we know more about Conrad Staugaard and his life, I enthusiastically agree with Henrik's earlier suggestion that we change this theme to be "Staugaard", which would also align with WinChloe. I can make necessary changes in PDB as a batch, and retain also "Pam-Krabbe" as a deprecated keyword, pointing to Staugaard. Pam & Krabbé are famous already, and only popularized Staugaard's funny idea. Any objections? (2021-05-08)
A.Buchanan: OK thank you: I've made the move. Please check the definitions, and let me know anything that needs changing (2021-05-09)
Henrik Juel: Very good, Andrew; the Staugaard fan club (both of us) thanks you
You might want to add that after a white Staugaard castling, wK is on e3 and promoted wR is on e2
I wonder whether the solution notation should be changed to 0-0-0-0-0 with 5 zeroes, so that the number of zeroes is one less than the length of the rook displacement for all three castlings (2021-05-09)
Henrik Juel: Forget my very last remark, please
Short and long castling has rook displacement = number of zeroes,
so Staugaard should remain with 6 zeroes, of course (2021-05-09)
A.Buchanan: Ok listed the target squares as requested. (2021-05-09)
A.Buchanan: Curious that this economy record must begin with a tempo move (2021-05-20)
A.Buchanan: Staugaard seems a much better basis than Chess960 for further generalization of castling. Basically move an unchecked royal king 2 unattacked square towards the rook, and the rook hops the otherside. This works whatever the gap between the two. This is more similar to rokagogo. (2021-05-21)
more ...
comment
Keywords: Unique Proof Game, Staugaard castling, Castling (2), Phoenix (t), Promotion (t), Tempo Loss, Economy record, Pure Round Trip (L3)
Genre: Retro, Fairies
Computer test: HC+ no orthodox solution in 7.0, and last Bl move can only have been 0^6 (else switchback, taking more than 7 Bl moves in total). Retracting 0^6, C+ Euclide 1.01 in 6.5
FEN: 1nbq1bnr/p1pprppp/4k3/8/8/6P1/PPPP1PBP/RNBQ1RK1
Input: A.Buchanan, 2021-05-08
Last update: Rainer Staudte, 2024-02-28 more...
25 - P1389458
Lord Dunsany
Andrew Buchanan

PDB Website 11/05/2021
"No more cross-capturing to inconvenience you, Milord."
Lord Dunsany, correction AB
P1389458
(10+9) C+
#3
1. 0-0-0! droht 2. Txb7 droht 3. Tb8#
1. ... Kd8 2. Txa6+ b6,Kc8,Ke8 3. Ta8#
play all play one stop play next play all
Mutex castling
Corrects P1323157.
Henrik Juel: If both White and Black can castle, there is no way to explain sTh7
If only White can castle, both black rooks are original
If only Black can castle, sTh7 is a promoted pawn
So the castlings are mutually exclusive, and the solution
1.0-0-0 thr. 2.Txb7 thr. 3.Tb8# is C+ Popeye 4.61 (2021-05-11)
Henrik Juel: I had a hard time finding the correct Popeye input, which is 'opt cas a1h8'
Good work, Andrew; if you continue like this, you may expect a peerage letter from the british queen, provided Scotland stays in the union... (2021-05-11)
A.Buchanan: Thanks Henrik: yes I can never remember these parameters, but Olive gave me a hint after I got it wrong :) I replaced wSa7 by wLa5 for an extra variation. These problems were just Christmas puzzles for Dunsany every year in the main Literary magazine of the time. So I fix it in that spirit, but I'm sure I've seen other more intricate problems where both sides have one side boxed in by possibly cross-capturing pawns depending on capture-counting (2021-05-11)
Henrik Juel: The additional variation is 1... Kd8 2.Txa6+ b6,Kc8,Ke8 3.Ta8#
Still C+ Popeye 4.61 (2021-05-11)
comment
Keywords: Castling
Genre: 3#, Retro
Computer test: HC+ simple retro thinking + Popeye v4.85
FEN: 4k2r/1p1p1p1r/pRpP1P2/B6p/8/7P/1PP3P1/R3K3
Input: A.Buchanan, 2021-05-11
Last update: A.Buchanan, 2021-07-09 more...
26 - P1394496
Vladimir Archakov
Andrew Buchanan

PDB Website 10/10/2021
VA, correction AB
P1394496
(15+3) C+
#2*
Set Play
1. ... Kxh1 2. Kf2#
1. ... Kxh3 2. Sf4#
1. ... Kxf3 2. Lb7#
BTM
1. ... hxg5 2. Sc3
2. ... Kxh1 3. Kf2#
2. ... Kxh3 3. Lf1#
2. ... Kxf3 3. 0-0#
play all play one stop play next play all
Corrects P0000914.
Black to move.
Missing White unit captured on h-file. So wPa promoted, hence 11 necessary captures by White, within budget.
more ...
comment
Keywords: No legal last move for Black, Mutate (2), Castling (wk)
Genre: 2#, Retro
Computer test: Henrik Juel: C+ Popeye 4.61 (2021-10-10)
FEN: 8/6PR/B6p/6BP/3P2Np/5P1P/3PN1kP/Q3K2R
Input: A.Buchanan, 2021-10-10
Last update: A.Buchanan, 2023-08-15 more...
27 - P1396163
Tivadar Kardos
Andrew Buchanan

PDB Website 24/11/2021
TK, correction AB
P1396163
(8+14) C+
h#3
1. cxb3ep+ Sb4+ 2. Kb1 Sxe2 3. b2 0-0#
R: 1. b2-b4 Tc3-a3+ 2. Sa3-c2
play all play one stop play next play all
Black captured 8 white men with pawns. Critically sBd & sBe never captured, therefore White pawns captured onto d- & e-files (to explain the pawn inversions there). Therefore wBb4 did not come from c3.
See P0574383.

With the ink still wet on this correction, I would like to remove sD. Sound by Popeye & Retractor, but needs an adapted proof game for C+.

Proof Game: 1. c4 a6 2. g3 Nc6 3. Bg2 Na5 4. Bc6 h5 5. Bb5 axb5 6. g4 c5 7. d4 cxd4 8. e4 f5 9. Be3 fxe4 10. f4 g5 11. Qf3 Nb3 12. Na3 hxg4 13. Nc2 gxf3 14. Rd1 Na1 15. Rd2 Ra3 16. Rg2 Rc3 17. a4 d3 18. Bf2 e3 19. Bg3 e5 20. Re2 e4 21. a5 d5 22. a6 d4 23. a7 Qd5 24. a8=R Qe5 25. Rf2 Kd7 26. Re2 Nf6 27. Rd2 Nd5 28. cxd5 Kd6 29. Rf2 Kc5 30. Re2 b6 31. Rd2 Kc4 32. fxe5 Kb3 33. Re2 fxe2 34. Rb8 Bg4 35. Rb7 Bf3 36. Rc7 Ka2 37. Bf4 gxf4 38. Rc6 Bb4 39. Rc5 Rh3 40. Na3 Ba5 41. Rc4 bxc4 42. Nc2 Ra3+ 43. b4
A.Buchanan: 6n1/8/1q6/b7/1Ppppp2/r2ppp1r/k1N1p2P/n3K1NR has one less piece again, but I prefer the current version as retro logic is more interesting. (2021-11-26)
James Malcom: Enjoy an optimal PG Andrew. The total sum of the queen & knight journeys is 8 no matter which knight ends up on a1. (2021-11-27)
A.Buchanan: :-) thanks James (2021-11-27)
more ...
comment
Keywords: En passant as key, Castling (wk)
Genre: h#, Retro
Computer test: C+ Popeye 4.61, Retractor 2.0 & example proof game.
FEN: 8/8/1p6/b2PP3/1Ppppp2/r2ppb1r/k1N1p2P/n3K1NR
Input: A.Buchanan, 2021-11-24
Last update: A.Buchanan, 2023-08-15 more...
28 - P1396304
Tivadar Kardos
Andrew Buchanan

PDB Website 27/11/2021
Happy Birthday to James Malcom!
A gift from Tivadar Kardos (helped a little by Andrew Buchanan)
I don't think this one needs a proof game :)
TK, version AB
P1396304
(11+13) C+
h#3
2 solutions
1. Lxa2 Txa2 2. 0-0-0 Txa7 3. Td7 Ta8#
1. Dg3 Txb1 2. Dxb3 Txb3 3. 0-0 Tg3#
1. Lxa2 0-0-0? 2. Dxg2 Tg1 3. 0-0 Txg2# (White can't castle)
play all play one stop play next play all
The cooked P0006972 can be fixed many ways. I wanted to find a single touch that would keep the intended solution, the intended try, and exactly one of the cooks which seemed worth saving, while eliminating all the other cooks.
Henrik Juel: Black captured [Lf1] and the remaining 4 missing white men with exdxcxTb2-b1=L and gxh
1.Bb1*a2 Ra1*a2 2.0-0-0 Ra2*a7 3.Rd8-d7 Ra7-a8 #
1.Qg8-g3 Ra1*b1 2.Qg3*b3 Rb1*b3 3.0-0 Rb3-g3 #
Not 1.Bb1*a2 0-0-0? 2.Qg8*g2 Rd1-g1 3.0-0 Rg1*g2 # (White may not castle, as he has moved his king)
Neat birthday greeting (2021-11-27)
James Malcom: Thanks for the warm gift Andrew. Huzzah! (2021-11-28)
comment
Keywords: Castling (sgsk), Cant Castler (wg), Obvious promotion (l)
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 + trivial retro-logic
FEN: r3k1qr/pp3p1p/1bp5/3pB2p/8/1P6/P1PPPPPP/Rb2K3
Input: A.Buchanan, 2021-11-27
Last update: A.Buchanan, 2021-11-28 more...
29 - P1398014
Tivadar Kardos
Andrew Buchanan

PDB Website 08/01/2022
TK, correction AB
P1398014
(6+16) C+
h#3
1. bxc3ep+ d3 2. 0-0 Tf4 3. Kh8 Txf8#
play all play one stop play next play all
Not R: 1. c3-c4? La6xb5? because Black's 10 captures are already accounted for: 6 pawn captures on files a-d, e.g.: bax, cxbxa, dxcxbxa + 4 waylaid pawns on files e-h or maybe 2 more pawn captures if bPe & bPf cross-capture.
Corrected version of P0003264, with extra tightness.
more ...
comment
Keywords: En passant as key, Castling (sk)
Genre: h#, Retro
Computer test: HC+ Popeye 4.61
FEN: N3k2r/6pp/1pn5/Pb2p3/RpP5/pr2qp2/p2P2n1/5Kb1
Input: A.Buchanan, 2022-01-07
Last update: A.Buchanan, 2022-03-20 more...
30 - P1398780
Andrew Buchanan
AA007 The Hopper Magazine I01 24/12/2021
P1398780
(16+15)
Drawn game. PG in 9.0
Moldenhauer: Computerprüfung: C- oder Cooked Stelvio 1.4 in 1 Sekunde.
Die Diagrammstellung ist verschieden erreichbar.
Hier 2 Möglickeiten:
1.Sa3 d5 2.Sb1 Kd7 3.f3 De8 4.Kf2 e5 5.Kg3 De6 6.Kh4 Dg6
7.Kh3 e4 8.fxe4 f6 9.e5 Ke8+
1.Sa3 d5 2.Sb1 Dd6 3.f3 Da6 4.Kf2 Sd7 5.Kg3 Dg6+ 6.Kh4 e5
7.Kh3 e4 8.fxe4 f6 9.e5 Sb8+ (2023-07-29)
A.Buchanan: Hi Moldenhauer this problem is sound. You are forgetting the constraint: "Drawn game". (2023-07-29)
Moldenhauer: Hi Andrew, ich habe deshalb nur die Diagrammstellung angegeben.
Ich hoffe Andrew ist erlaubt! Mein Vorname ist Klaus. (2023-07-29)
A.Buchanan: Hi Klaus nice to meet you, thanks for all your work. The point of HC+ is that it combines human & computer logic intelligently. It makes zero sense to solve robotically for 9.0. It is definitely valuable to solve this kind of stipulation (1) as PG in 5.0, and then (2) as PG A-B for 2.0. Apparent duals can then be resolved through reasoning about castling, e.p. and premature draw. (2023-07-29)
comment
Keywords: Draw by repetition, Unique Proof Game, Constrained problem, Castling, En passant (not!)
Genre: Retro
FEN: rnb1kbnr/ppp3pp/5pq1/3pP3/8/7K/PPPPP1PP/RNBQ1BNR
Input: A.Buchanan, 2022-01-31
Last update: Miguel Ambrona, 2023-07-26 more...
31 - P1398939
Edgar Fielder
Andrew Buchanan

Discord Chess Problems & Studies Server 07/022022
EF, version AB
P1398939
(13+10)
h#1
R: 1. Dg4-g3 Kd8-e8 2. Dg5-g4 Kc8-d8 3. Dg6-g5 Kb7-c8 4. Df6-g6 Tb8-h8 5. De6-f6 Kc8-b7 6. Dd6-e6 Kd8-c8 7. Dc6-d6 Ke8-d8 8. Db6-c6 Kf8-e8 9. Da7-b6 Kg8-f8 10. Db7-a7 Te8-b8 11. Db8-b7 Tf8-e8 12. b7-b8=D 0-0 13. c6xDb7 Da8-b7 14. d5xLc6 Dd8-a8 15. d4-d5 Lb7-c6 16. e3xSd4 Lc8-b7 17. f2xSe3 c6-c5 18. h5-h6 b7xLc6 is one of many possible histories, but all involve hidden castling
play all play one stop play next play all
Retro solution (which works for Fielder's original too).
Pawn captures: white missing LSBf, captured by axbxc,bxc. Therefore wBf captured at least 3 times fxexdxc, also exd & sLf8 died at home. So one missing black unit unaccounted for currently.
Cage can only be unlocked by exd3, but wLf must be returned home prior to this. Can only be uncaptured by sBb7xLc6-c5. If wPf did not promote, it was captured by sBa on b6 after 5 captures or on c5 after 4 captures. The latter is not possible, as wBc4 never left its file. The former is not possible, because sD would be unavailable for capture until b7xc6, which only happened after the cage was formed.
Therefore wBf promoted, and must have captured four times to reach b-file, accounting for the final capture. When it promoted on b8, sBb had already moved, capturing wLf and therefore the cage was already formed. So wDg3 is the promoted unit. If wBexd3 was capture of sLc, then there is deadlock between the two releases of bishops, so sLc was captured by wBf, hence path to promotion shifted to light squares (i.e. via c6 not b6) so sBc5 was already in place. When b7-b8=D, all the other White pieces (except possibly for wPh6, bK & bRh8) were already in place.
There is now a time-critical retraction, as White has at most 7 moves (not 9, because must release wRh before wLf is free) before sBb7xLc6, with sD & sLc sealed inside. So R: 1. b7-b8=D ~ 2. c6xDb7 zB Da8-b7 3. d5xLc6 Dd8-a8 4. d4-d5 Lb7-c6 5. e3xSd4 Lc8-b7 6. f2xSe3 c6-c5 7. h5-h6 b7xLc6. Where was bK while all this was happening. There is only one spare tempo (h4-h5) If bK was off the back rank, there was not enough time to retract back there. So the only possibility is that Black was already castled, and can uncastle when the black cage is closed. The missing move can be R: 1. ... 0-0.
Since castling is illegal in the forward play, h#1 is unique with Donati theme as wQ revisits the promotion square:
1. c6 Db8# not
1. 0-0? Dxg7#
cheeky retro-active version of P0001136
A.Buchanan: Looking at the original, I am wondering why wBh cannot be on h5. It clearly cannot retract to h3, but how many times is it needed to retract if White retracts from the critical position 1Q3rk1/2pppppp/8/2p4P/2P5/PPRP4/RBpP1PP1/N1K5 (2022-02-07)
A.Buchanan: Maybe the distinguished composer felt that the more spare White moves has, the more creditable is the fact that Black had no way to avoid prior castling. The problem is still sound either way. Of course, with the h#1 version, wBh6 is mandatory. wD location was pretty much arbitrary in the original, but now there is only one wD location for soundness: g3. (e5 & g4 are unsound). (2022-02-07)
A.Buchanan: The solution given in Keym’s wonderful “Eigenartige Schachprobleme” uses an unnecessary move by wPh. (2022-02-23)
A.Buchanan: In offering this version, I do not think that pure retros are in anyway inferior to forward problems, which was perhaps the motivation for forward stipulations in the days of yore. Rather, the aesthetic tension between past and future never tires for me. It is not an issue to me whether the balance of interest in a retro-active problem be equally divided between the two directions. Rather, it’s essential that the position have two readings: that the pieces have two purposes. This formal requirement of double meaning which is ubiquitous and quotidian in a cryptic crossword should also find a place near to the hearth in chess problems. So Morse might welcome Dexter. (2022-02-23)
more ...
comment
Keywords: Cant Castler, Castling Paradox (hidden sK), Donati Theme (wD), Castling in the retro play (wk)
Genre: h#, Retro
Computer test: Substantial retro thinking to show castling illegal + trivial v4.87 for forward play
FEN: 4k2r/2pppppp/7P/2p5/2P5/PPRP2Q1/RBpP2P1/N1K5
Input: A.Buchanan, 2022-02-07
Last update: A.Buchanan, 2023-08-15 more...
32 - P1399112
Werner Kuntsche
Valery Liskovets
Andrew Buchanan

PDB Website 14/02/2022
WK, correction AB
P1399112
(5+8) C+
h#3 AP

No solutions except for those beginning with e.p.
297 candidate solutions begin 1.gxf3ep, but only one includes castling. Queenside 2. ... 0-0-0
22 candidate solutions begin 1.fcxd3ep, but only one includes castling. Kingside 2. ... 0-0
In some way, these are trying to be combined so that from AP perspective, White's last move can only have been double hop with wBd or wBf.
We need a clear delineation of the precise PRA-AP algorithm to be followed.

The point: if this problem is "sound", then surely P1382808 is "unsound", because there only one of the two parts needs to prove that White castling rights remain, so there are 4 cooks.
This is an important schema for AP. Previous cooked problems P0002476 & P0004295 (together with versions of each lacking sBe3) had multiple chess cooks that do not involve e.p. as key. This chessically sound composition allows us to focus on the fundamental theoretical issue of AP.

The double e.p. idea cannot work as an AP retro strategy problem, because one can never prove that one double pawn hop rather than the other occurred. PRA+AP seems potentially feasible, but I see no clear statement of how the normal PRA method should be extended to this case. All prescriptive suggestions are welcome.

In WinChloe, I found a correction from 2002 by Valery Liskovitz, just posted in PDB as P1401449. However it used three extra pawns, rather than 2, so the current version still has merit, but I will add Valery as co-corrector.

See also P1399178.
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comment
Keywords: a posteriori (AP) (Type Petrovic), En passant as key (2), Symmetrical position, Symmetrical solution, Castling (wb)
Genre: h#, Retro
Computer test: HC+ Forward play proved by Popeye v4.87 AP logic requires some framework but I think we know we want this cool idea to end up being sound.
FEN: 8/8/2p3p1/8/2pPkPp1/2n1p1n1/8/R3K2R
Input: A.Buchanan, 2022-02-14
Last update: A.Buchanan, 2022-05-24 more...
33 - P1399805
Giuseppe Brogi
Andrew Buchanan

Discord Chess Problems & Studies Server 15/03/2022
GB, correction AB
P1399805
(8+14)
h#2
b) sSa1 -> wS
a) 1. T2xh3 Txh3 2. 0-0 Th8#
b) 1. La4 0-0 2. Tf8 Te1#
play all play one stop play next play all
Colour of Sa1 is irrelevant to forward play, except for castling rights. Ignoring these retro concerns, there are two candidate solutions.
Suppose that both castling rights remain. Then sTh2 is original sTa8, and black b&c & white g&h pawn pairs have both cross-captured. However White has made 1 visible pawn capture, Black 6. In (a) this leaves 2+1 unaccounted for; in (b) 1+2. So at most one side can have cross-captured, so in each twin just one side can retain castling rights, allowing just one candidate to work in each.
Corrects P0000899. See P1399806, a companion problem.
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comment
Keywords: Cant Castler (wksk), Castling (wksk), Cross-capture (s,w)
Genre: h#, Retro
FEN: 4k2r/p2p1Np1/1pp2p2/1b3p2/8/p4PPP/B4P1r/nn2K2R
Input: A.Buchanan, 2022-03-15
Last update: A.Buchanan, 2023-04-01 more...
34 - P1399806
Giuseppe Brogi
Andrew Buchanan

Discord Chess Problems & Studies Server 15/03/2022
GB, correction AB
P1399806
(13+9) C+
h#2
b) sSa5 -> wS
a) 1. f5 Le5 2. 0-0 Th8#
b) 1. Kd8 0-0-0 2. Te8 Lf8#
play all play one stop play next play all
Colour of Sa5 is irrelevant to forward play, except for castling rights. Ignoring these retro concerns, there are two candidate solutions.
Suppose that both castling rights remain. Then wTh7 is original wTh1, and both pairs of g&h pawns have cross-captured. However White has made 6 visible pawn captures, Black just 1. In (a) this leaves 2+1 unaccounted for; in (b) 1+2. So at most one side can have cross-captured, so in each twin just one side can retain castling rights, allowing just one candidate to work in each.
Corrects P0003736. See P1399805, a companion problem.
A.Buchanan: Oops this one doesn’t quite work I will fix it in the morning (2022-03-15)
Mario Richter: Hi Andrew, it would be nice to know the cook. Can you please give it - either here or if you prefer, via email? (2022-03-16)
A.Buchanan: Hi Mario: thanks for your interest. The transient version 4k2r/N1p2p1R/p1pB1ppp/npP5/5P2/5PPP/2P2P2/R3K3 a) allowed wPaxb=R then entering the cage disrupting b0-0 rights. That's 5 pawn captures by White. In the mean time, Black only has two visible pcs, with 4 captures available, so wRh1 (and another White officer) can be captured by officers without disrupting w0-0-0 rights. wSa7 is unhelpful in trying to fix it, but despair turned to joy when I realized that wPb6 & bPc7 both cover c7, and when the latter is missing, the former is not a promotion risk. Hence the new version which the Discord community provisionally thinks are sound. (2022-03-16)
comment
Keywords: Castling (wgsk), Cant Castler (wgsk), Cross-capture (s,w)
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 + simple retro-logic
FEN: 4k2r/Np3p1R/1PpB1ppp/n1P5/P7/6PP/PP3P2/R3K3
Input: A.Buchanan, 2022-03-15
Last update: A.Buchanan, 2023-03-31 more...
35 - P1400824
Otto Kerekes
Tivadar Kardos
Andrew Buchanan

France-Echecs 23/04/2022
OK & TK, correction AB
P1400824
(11+15)
h#2
b) wBg2 -> sB
a) 1. cxd4 Lxc4 2. Dd5 Ld3#
not 1. cxd3ep? Txd1 2. dxc2 Lxc2# because last move was 0-0.
b) 1. cxd3ep cxd3+ 2. Kf3 Lxd1# because last move was d2-d4.
play all play one stop play next play all
Corrects P0005275
Henrik Juel: C+ Popeye 4.61 and analysis (2022-04-23)
Henrik Juel: solutions
a) 1.cxd4 Lxc4 2.Dd5 Lxc2#
not 1.cxd3ep? Txd1 2.dxc2 Lxc2, because last move could be 0-0
b) 1.cxd3ep cxd3+ 2.Kf3 Lxd1# (2022-04-23)
Mario Richter: In a), why not 1. cxd3ep?
Andrew: "because last move was 0-0."
Henrik: "because last move could be 0-0"
Mario: "because d2-d4 definitively was not White's last move" (2022-04-24)
Henrik Juel: You are right, Mario
But my argument suffices to rule out the ep capture, which is allowed only if you can show that last move was d2-d4 (2022-04-24)
A.Buchanan: Thanks Mario. I think that our opinions are consistent. I wanted to emphasise the castling because of Valladao. In b), h8=L is accurate, even if we never know the result of e8=X in either twin. (2022-04-25)
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comment
Keywords: Valladao Task, En passant as key, Castling in the retro play, Promotion (L), Castling (wk)
Genre: h#, Retro
Computer test: HC+ Popeye v4.61 & Retractor 2 which determines that only candidate last move are a) d2-d4 & 0-0 b) d2–d4. Manual logic determines in a) that last move was not in fact d2-d4 because wPe would promote on wrong colour square. Also C+ with rawbats
FEN: 8/p1p5/1B6/q1p1b3/r1pPkpp1/1Bp3Pb/PPP2PPr/1n1n1RK1
Input: A.Buchanan, 2022-04-23
Last update: A.Buchanan, 2023-08-15 more...
36 - P1400896
Tivadar Kardos
Andrew Buchanan

Discord Chess Problems & Studies Server 26/04/2022
TK, correction AB
P1400896
(7+15) C+
h#3 AP
1. gxf3ep+ e3 2. 0-0-0 Tb4 3. Tg4 Tb8#
play all play one stop play next play all
Black has visibly made 6 pawn captures right to left. Two captures are required to resolve the h-file (either two pcs by black, or wPgxh with wPh waylaid). If black preserves castling rights, then White pawns on a & d files require one more capture by either side to resolve. So all 10 captures accounted for. If wKc1 then bPdxc but this implies 2 more captures, only one of which can be taken from d file. Similarly wPfxexf too expensive. So If black can castle, then the last move was indeed pawn double hop.

The castling serves two purposes: justifying the ep capture and enabling the mate: there are no retro tries in this problem.
Author: Kardos' cooked P0003269 was from 1956 just after AP compositions began to appear, and I can't decide whether he intended to include AP but it seems to fit this corrected version.
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comment
Keywords: a posteriori (AP) (Type Petrovic), Castling (sg), En passant as key
Genre: h#, Retro
Computer test: C+ Popeye 4.61 and analysis
FEN: r3k3/3q4/5p2/5pbP/n4PpR/1pp3rp/2p1P1pB/N1K3n1
Input: A.Buchanan, 2022-04-26
Last update: A.Buchanan, 2023-09-11 more...
37 - P1401525
Joao Baptista Santiago
Andrew Buchanan

PDB Website 30/05/2022
JBS, correction AB
P1401525
(11+14) C+
h#2* (AP)
1. ... Kd2 2. e3+ fxe3#
1. bxc3ep b3 2. Kxd3 0-0-0#
play all play one stop play next play all
Black has no tempo moves to convert the set play to a main play solution. Rc5~,Se5~,e3,Sf1 all disrupt the set play.
The main play castling is needed both for the mate and for the legitimization.
Corrects P1401496
Henrik Juel: analysis
Black captured [Pa2] with an officer and cxb, dxe, exf, and f3xg2
White captured g4xLh5 and h2xDg3, so if he may castle, Black may capture ep now (2022-05-30)
A.Buchanan: A detail I hadn't noticed: bPh never captured, so wPh5 must have arrived on h-file *above* the light square h3. If it was gxh4, then there was no light square to capture light bB, so it was gxh5. But the capture might have been h3xBg4xQh5. The problem is still sound: the last move can't have been h4-h5. (2022-05-30)
more ...
comment
Keywords: a posteriori (AP) (Type Petrovic), Castling (wg), En passant as key
Genre: h#, Retro
Computer test: HC+ Popeye 4.61 and analysis
FEN: 8/8/pp2P3/brr1n2P/1pPkp1p1/B2P1pPp/1P3Ppn/R3K1N1
Input: A.Buchanan, 2022-05-30
Last update: A.Buchanan, 2022-05-30 more...
38 - P1401526
Zoltan Laborczi
Gabor Tar
Andrew Buchanan

PDB Website 30/05/2022
ZL & GT, version AB
P1401526
(4+8) C+
h#2 (AP)
3.1...
1. Tb3 Lxc4 2. Txb4 Txa2#
1. Kxb4 Tb1+ 2. Ka4 Lb5#
1. cxb3ep 0-0-0! (Td1?) 2. e4 Td4#
play all play one stop play next play all
Economizes P1080354 by 2 units, adding a solution.
more ...
comment
Keywords: a posteriori (AP) (Type Petrovic), Castling (wg), En passant as key
Genre: h#, Retro
Computer test: C+ Popeye 4.61
FEN: 8/1p6/B7/p3p3/kPp5/r1p5/p7/R3K3
Input: A.Buchanan, 2022-05-30
Last update: A.Buchanan, 2023-05-21 more...
39 - P1401566
Jean-Michel Trillon
Siegfried Hornecker
Andrew Buchanan

Discord Chess Problems & Studies Server 02/06/2022
J-MT, correction SH & AB
P1401566
(7+8) C+
#4 AP
Maximummer
b) g6->g5
a) 1. Ld6 Td8 2. fxg6 Txd5 3. g7 Th5 4. g8=D#
b) 1. fxg6ep Txd5 2. Le5 0-0-0 3. g7 Th8 4. gxh8=D,T#
play all play one stop play next play all
What did Black play last, and why not b7-b5?
a) Can only be Kxe8 to escape check. Thus castling rights are definitely lost.
b) Also the possibility of g7-g5, so 000 rights can remain. This breaks the earlier solution but allows another solution in which AP retro-justifies ep with 000, which is also necessary for the mate. The solution beginning 1.Ld6 does not work any more, because under RS convention, castling is legal and so must be played.
FYI: here are two non-unique games validated by Jacobi v0.7.5 to prove the legality of the diagram positions. 000 rights remain in b, while in a are retained until the penultimate move.
a) 1.e4 Sf6 2.a4 Sd5 3.exd5 Sc6 4.a5 Sb4 5.h4 Sd3+ 6.Ke2 Sxb2 7.g3 Sc4 8.Bb2 Sa3 9.Be5 Sxc2 10.Bxc7 Sb4 11.Sc3 Sa6 12.Se4 Sb8 13.Sg5 Sa6 14.Se6 Sb8 15.Sxd8 Sa6 16.Bb8 Sb4 17.Sxf7 Sa6 18.Sh6 Sc5 19.Ra4 Sa6 20.Rc4 Sc7 21.Rc6 Sa6 22.Rd6 Sb4 23.Sf3 Sa2 24.Sg5 Sb4 25.Se6 Sa2 26.Sxf8 Sb4 27.Sg6 Sa6 28.Sxe7 Sb4 29.Qc2 Sa6 30.Kd3 Sc7 31.Be2 Sa6 32.f4 Sc7 33.Rb1 Sa6 34.Rb5 Sc7 35.Kc3 Sa6 36.Kb2 Sc7 37.Ka1 Se6 38.Bg4 Sd8 39.Rf6 Sc6 40.Be6 Sd8 41.Sf7 Sc6 42.Sg5 Sd8 43.Qxc8 Rf8 44.Bg4 Rh8 45.Sf5 Rf8 46.Sd4 Rh8 47.Sde6 Rf8 48.Kb2 Rxf6 49.Ka1 Rh6 50.Bh5+ Rxh5 51.Sd4 g6 52.g4 a6 53.Qc1 Sc6 54.f5 Sxd4 55.Rb3 Sxb3+ 56.Ka2 Sxa5 57.Ka1 Sc6 58.Ka2 Se5 59.Ka1 Sf7 60.Ka2 Sxg5 61.Ka1 Sf7 62.Qc8+ Sd8 63.Qxd8+ Kf7 64. Qe8+ Kxe8
b) 51. … a6 52.Qc1 Se6 53.Qc2 Sxg5 54.f5 Sf3 55.g4 Sxd4 56.Rb3 Sxb3+ 57.Ka2 Sxa5 58.Qb1 Sb3 59.Qa1 Sxa1 60.Kxa1 g5
Corrects P1401480.
Henrik Juel: a) 1.fxg6 Txd5 2.Le5 0-0-0 3.g7 Th8 4.gxh8=DT#
b) 1.fxg6ep Txd5 2.Le5 0-0-0 3.g7 Th8 4.gxh8=DT# (2022-06-02)
Henrik Juel: a) is C+ Popeye 4.61, except for the promotion mate dual; no AP here
In b) Popeye with 'opt enp g6' gives the intended solution; here the castling is needed to rule out the possibility of Kf7xDe8 as last move
But how do we know that last move was not f6xg5 or h6xg5? (2022-06-02)
A.Buchanan: Hi Henrik thanks for examining this.
In a), the last move must have been Kxe8 to deal with checking piece. Otherwise black would have played e.g. b7-b5. If you forbid castling in Popeye you will see a completely different solution.
In b) hxg5 or fxg5 is too short to compete with b7-b5. (2022-06-02)
Henrik Juel: Yes, I missed b7-b5
Popeye with 'opt noc a8' gives this solution for a) 1.Ld6 Td8 2.fxg6 Txd5 3.g7 Th5 4.g8=D#
Very nice, with analysis in both parts (2022-06-02)
comment
Keywords: a posteriori (AP) (Type Petrovic), Maximummer, Castling (sg), En passant as key, Promotion (D,D/T), Valladao Task, Retro Strategy (RS)
Genre: h#, Retro, Fairies
Computer test: HC+ Popeye v4.87 for forward logic, Jacobi v0.7.5 to validate demo games & humans for non-trivial retro-logic
FEN: rB2k3/1p1p3p/p5p1/3P1P1r/6PP/8/3P4/K7
Input: A.Buchanan, 2022-06-02
Last update: A.Buchanan, 2022-06-03 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...
41 - P1402593
Andrew Buchanan
PDB Website 09/07/2022
after G.P.Latzel
P1402593
(10+4)
h#1.75 (-:
hint rot13: pbqrk negvpyr svsgrra
0. ... [-bPg5] 1. Lxb3 Ta8#
play all play one stop play next play all
Clearly an unfinished move joke. By a usual convention for these things, a player might be halfway through a castling, an en passant, or a promotion. 1.75 is nearly 2.0, so Black would be the moving player.

Black is not in the middle of an e.p. or castling, so the only possibility is a promotion. Black has lifted up the pawn, to replace it with an officer on the 8th rank. However, White has apparently made 12 pawn captures, accounting for all missing Black units, so Black is not part way through promoting a pawn.

Therefore it's not Black in the middle of a move. By a joke application of Article 15, we say that it's *White* in the middle of a move instead. So 1.75 - 0.5 = 1.25 and it's h#1.25.

- White can't be part way through a promotion, because all White pawns are on the board.
- If White were in the middle of castling, then the pawn capture balance would be ok, but Black would have no prior move.
- If White were in the middle of en passant h5xg6, then bPg5 can help with capture balance, but still there is one capture short for the balance.
- So White is in the middle of en passant f5xg6. If we complete the joke move by removing bPg5, then the position is legal, with 12 White pawn captures and 13 missing Black units. A sound h#1 awaits.
After P0004346
Henrik Juel: Not completion of 0-0-0, because Black has no last move
Completion of f5xg6ep is feasible, and then 1.Lxb3 Ta8#
Stipulation should be h#1.25, I think (2022-07-10)
A.Buchanan: Hi Henrik: it’s intended to be h#1.75 :-) Can black complete any Valladao move? And if not then what do we do? :-) (2022-07-10)
Henrik Juel: Thanks Andrew
So Black must complete a move, but his four men are stuck, and white pawns captured the remaining 12 black men; so there is nothing for Black to complete
Looks like a weird joke... (2022-07-10)
A.Buchanan: Sorry you don't like the Valladao joke Henrik. "1.75 minus 0.5 = 1.25" is a novel way to combine "unfinished move" with Article 15. I also like the fact that all the cases of pawn capture counting are exact, with no "retro dressing" unit purely to contribute to a balance.s (2022-07-10)
comment
Keywords: Joke, Complete an unfinished move, En passant, Castling (wg Not!), Promotion (Not!), No legal last move for Black
Genre: h#, Retro
FEN: 7k/5p1P/5PPP/1P4p1/b7/1P6/6PP/R1K5
Input: A.Buchanan, 2022-07-10
Last update: A.Buchanan, 2023-12-08 more...
42 - P1408358
Andrew Buchanan
10 Problemas 36, p. 1190, 10/2021
P1408358
(15+13) C+
PG in 14.5
1. e4 c5 2. Lb5 c4 3. Sf3 c3 4. 0-0 cxd2 5. c4 f6 6. Db3 d1=L 7. Lh6 Kf7 8. c5+ d5 9. cxd6ep+ Kg6 10. Se5+ Kh5 11. Le8+ g6 12. Lg7 Lh3 13. gxh3 Lg4 14. f3 Kh4 15. fxg4
play all play one stop play next play all
Objective: co-record shortest achievement of task, followed by artistic continuation.
Also version rnbqBbnr/pp2p1Bp/3P1pp1/4N2k/4P3/1Q5P/PP3P1P/RN1R2K1 PG in 14.0 mentioned in article. This offers different artistic continuation (with Pronkin instead of Ceriani-Frolkin).
more ...
comment
Keywords: Unique Proof Game, Valladao Task, Castling (wk), En passant, Promotion (l), Prenix (l), Ceriani-Frolkin Theme (l)
Genre: Retro
Computer test: HJ: C+ Stelvio 1.0
FEN: rn1qBbnr/pp2p1Bp/3P1pp1/4N3/4P1Pk/1Q5P/PP5P/RN3RK1
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-03-20 more...
43 - P1408359
Andrew Buchanan
9 Problemas 36, p. 1190, 10/2021
P1408359
(14+13) C+
PG in 12.0
1. e4 b5 2. e5 b4 3. Lb5 b3 4. Se2 bxc2 5. 0-0 cxb1=S 6. Dc2 f5 7. Dxc7 Kf7 8. Dc4 d5 9. exd6ep+ Kf6 10. Dxg8 Le6 11. d7 Dc8 12. d8=S Sd7
play all play one stop play next play all
Objective: co-record shortest achievement of task, followed by artistic continuation.
more ...
comment
Keywords: Unique Proof Game, Valladao Task, Castling (wk), En passant, Promotion (sS), Prenix (s), Phoenix (S)
Genre: Retro
Computer test: HJ: C+ Stelvio 1.0
FEN: r1qN1bQr/p2np1pp/4bk2/1B3p2/8/8/PP1PNPPP/RnB2RK1
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-03-20 more...
44 - P1408360
Andrew Buchanan
8 Problemas 36, p. 1190, 10/2021
P1408360
(13+13) C+
PG in 11.5
1. d3 e5 2. Sd2 e4 3. Sdf3 exf3 4. b4 fxe2 5. La3 exf1=S 6. Dg4 Ke7 7. 0-0-0 Kd6 8. b5+ c5 9. bxc6ep+ Kc7 10. Dxd7 Kb6 11. g4 Sg3 12. hxg3
play all play one stop play next play all
Objective: co-record shortest achievement of task, followed by artistic continuation.
more ...
comment
Keywords: Unique Proof Game, Valladao Task, Castling (wg), En passant, Promotion (s), Ceriani-Frolkin Theme (s)
Genre: Retro
Computer test: HJ: C+ Stelvio 1.0
FEN: rnbq1bnr/pp1Q1ppp/1kP5/8/6P1/B2P2P1/P1P2P2/2KR2NR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-03-20 more...
45 - P1408361
Andrew Buchanan
2 Problemas 36, p. 1189, 10/2021
P1408361
(15+13) C+
PG in 8.0
1. e4 Sf6 2. Ke2 Sd5 3. exd5 g5 4. d6 Lh6 5. dxc7 0-0 6. cxb8 Da5 7. Ke3 g4+ 8. f4 gxf3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to either minor officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sk), En passant
Genre: Retro
Computer test: HJ: with wSd8 C+ Stelvio 1.0
FEN: rn1P1rk1/ppp2p1p/3p1n1b/8/8/4Kp2/PPPP2PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
46 - P1408362
Andrew Buchanan
2 Problemas 36, p. 1189, 10/2021
P1408362
(15+13) C+
PG in 8.0
1. e4 Sf6 2. Ke2 Sd5 3. exd5 g5 4. d6 Lh6 5. dxc7 0-0 6. cxb8 Da5 7. Ke3 g4+ 8. f4 gxf3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to any officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sk), En passant
Genre: Retro
Computer test: HJ: with wSb8 C+ Stelvio 1.0
FEN: rPb2rk1/pp1ppp1p/7b/q7/8/4Kp2/PPPP2PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
47 - P1408363
Andrew Buchanan
3 Problemas 36, p. 1189, 10/2021
P1408363
(15+13) C+
PG in 8.0
1. d4 Sf6 2. Kd2 Se4+ 3. Ke3 Sc5 4. dxc5 g5 5. c6 Lh6 6. cxb7 0-0 7. bxc8 g4+ 8. f4 gxf3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to any officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sk), En passant
Genre: Retro
Computer test: HJ: with wSc8 C+ Stelvio 1.0
FEN: rnPq1rk1/p1pppp1p/7b/8/8/4Kp2/PPP1P1PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
48 - P1408364
Andrew Buchanan
4 Problemas 36, p. 1189, 10/2021
P1408364
(15+12) C+
PG in 8.0
1. d4 Sc6 2. Kd2 Se5 3. dxe5 Sf6 4. exf6 g5 5. fxe7 Lh6 6. exd8 0-0 7. Ke3 g4+ 8. f4 gxf3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to either minor officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sk), En passant
Genre: Retro
Computer test: HJ: with wSd8 C+ Stelvio 1.0
FEN: r1bP1rk1/pppp1p1p/7b/8/8/4Kp2/PPP1P1PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
49 - P1408365
Andrew Buchanan
5 Problemas 36, p. 1189, 10/2021
P1408365
(15+14) C+
PG in 8.0
1. f4 e6 2. f5 Lc5 3. f6 Se7 4. fxe7 Lb6 5. exd8 c5 6. Kf2 0-0 7. Ke3 c4+ 8. d4 cxd3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to either minor officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sk), En passant
Genre: Retro
Computer test: HJ: with wSd8 C+ Stelvio 1.0
FEN: rnbP1rk1/pp1p1ppp/1b2p3/8/8/3pK3/PPP1P1PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
50 - P1408366
Andrew Buchanan
6 Problemas 36, p. 1189, 10/2021
P1408366
(15+14) C+
PG in 8.0
1. f4 d5 2. f5 Ld7 3. f6 Lc6 4. fxe7 Sd7 5. exf8 Dg5 6. Kf2 0-0-0 7. Kf3 d4+ 8. e4 dxe3ep+
play all play one stop play next play all
Objective: record achievement of task. Promotion can be to either minor officer, but prefer to keep the "stem cell" to avoid arbitrary choice of non-standard material.
more ...
comment
Keywords: Unique Proof Game, Dummy Pawn (in diagram), Valladao Task, Golden Age (Dummy Pawn), Castling (sg), En passant
Genre: Retro
Computer test: HJ: with wSf8, C+ Stelvio 1.0
FEN: 2kr1Pnr/pppn1ppp/2b5/6q1/8/4pK2/PPPP2PP/RNBQ1BNR
Input: A.Buchanan, 2023-03-19
Last update: A.Buchanan, 2023-08-04 more...
51 - P1409841
Andrew Buchanan
1 Phénix 331, p. 12922, 06/2022
after A.Lubusov
P1409841
(15+6) C+
h#2* (AP)
1. ... e6 2. 0-0? Lxh7# (castling rights lost)
1. ... Txh7 2. Tf8 Te7#

1. cxb3ep Txh7 2. Tf8? Te7# (ep needs AP justification)
1. cxb3ep e6 2. 0-0! Lxh7#
play all play one stop play next play all
White pawns have captured 9 times right-to-left, accounting for all but one missing Black unit. So by parity, there were no other pawn captures by White. So wBb never left that file, and Black cannot have just played Bb3xa2 behind it. sBa was waylaid on a-file by an officer.

So if Black moved last, it must have been Ke8 or Th8, and Black has lost castling rights.

On the other hand, if White moved last, then Black needs a tempo move. The only possible one is ep capture. (1. Tg8+? is check.) But the ep capture is only legal if Black retains castling rights, so Black's second move must indeed be 0-0 for A Posteriori justification.

In this case, last moves were R: 1. b2-b4 b3xDa2 & e.g. 2. Le3-d4,~ b4-b3 3. d4xSc5,~ Sa6-c5,~ with many ways for White to release Black.
Corrects P0000615.
more ...
comment
Keywords: a posteriori (AP), RIFACE Retro Solving Tourney (2022), En passant as key, Castling (sk), Tempo Move, waylaid (sBa)
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 & simple retro thinking
FEN: 4k2r/1N1p3p/3P4/1PPPP3/1PpBBP2/P1N3K1/p7/R6R
Input: A.Buchanan, 2023-05-20
Last update: A.Buchanan, 2023-09-11 more...
52 - P1413923
Andrew Buchanan
R611 The Problemist 07/2023
P1413923
(15+11)
Proof Game in 12.5
Game over!

A long-standing question (since a problem by Michel Caillaud P1004030, and also one by Guus Rul) asks how the Draw by Triple Repetition (3Rep) convention interacts with the Dead Position rule (DP). This is not an issue over the board, since 3Rep must be claimed. Miguel Ambrona proposed that for retro problems, DP rule has visibility of any looming 3Rep or 50M draw, while for purely forward problems, e.g. help dead position (HDP), it does not. This distinction works extremely well: it enables problems such as Michel's and this new one, while allowing us to eliminate a class of cooks which would be ubiquitous in longer HDP problems. So the HDP design space does not hit an effective ceiling at 4.0 moves. The concept of "retro problem" is already used in Codex Articles 17 & 17A for 50 move rule & DP, so is not new.
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comment
Keywords: Unique Proof Game, Constrained problem, Draw by repetition, Castling, En passant
Genre: Retro
FEN: 2Q1kb1r/1pp1ppp1/3q3p/2Pp1R2/8/1P6/1P1P1PPP/1NB1KBNR
Reprints: www.chess.com 18/12/2023
Input: A.Buchanan, 2023-12-05
Last update: A.Buchanan, 2023-12-18 more...
53 - P1413924
Johannes Jacob Burbach
Alain C. White
Andrew Buchanan

PDB Website 05/12/2023
JJB & ACW, version AB
P1413924
(4+6) C+
h#2
b) -sBg6h7
a) 1. Ta5 Kd1 2. Ta2 Kc2# (not 1.Ta7?etc Lxc3 because White may not castle)
b) 1. Ta7 Lxc3 2. Ta2 0-0# (last move could be 0.h7-h8=L)
play all play one stop play next play all
See P0003666
A.Buchanan: Apart from having removed wBe2/sBe3, I don't think this is an improvement. In the original, sBh6 gave and took. The version is more economical but there's two pawns difference between the twins. (2023-12-06)
more ...
comment
Keywords: Cant Castler, Castling (wk), Remove pieces
Genre: h#, Retro
Computer test: HC+ Popeye v4.87 + trivial retro logic
FEN: 7B/6rp/6p1/7r/8/2p5/1P6/k3K2R
Input: A.Buchanan, 2023-12-05
Last update: A.Buchanan, 2023-12-05 more...
54 - P1415606
Maurice Jago
Andrew Buchanan

PDB Website 07/03/2024
MJ, correction AB
corrects 8202v Die Schwalbe, p.148, 10/1980
P1415606
(8+15)
h#2
b) sBb4->b5
Supersedes P0003659.
"The noted Cornish problemist, Dr. Maurice Jago was most prolific during the war when he was a lieutenant in the Royal Army Medical Corps. He became increasingly interested in the more flamboyant and unusual kinds of positions and problems." (www.keverellchess.com, now closed)
Yuri Bilokin: perhaps such a version does not harm the author's intention –wNa7, -wNa8, -wBb8, -wPd3, -bRc8, -bPc7, -bPe7 8/8/1Pqp4/2bb4/1p6/n1p2rP1/1PP1P2k/R3KQ1n (8+12) h#2 b) bPb4-b5 (2024-03-10)
Yuri Bilokin: slip of the pen -wNa7, -wNa8, -wBb8, -wPd3, -bRc8, -bPc7, -bPe7, -bPa4, -bPg6 8/8/1Pqp4/2bb4/1p6/n1p2rP1/1PP1P2k/R3KQ1n (8+10) h#2 b) bPb4-b5 (2024-03-10)
A.Buchanan: Hi Yuri thanks yes it’s more than intention here. In b need to ensure that White can’t have just played axb6, fxg3 or g2-g3, in order to eliminate the castling try: the extra pieces are all to ensure this (2024-03-11)
Yuri Bilokin: Hi Andrew. I apologize, I didn't go there, although the white horse on the a8 square still bothers me. (2024-03-11)
A.Buchanan: WP cap: axb BP caps: fxexdxc. bPh must have promoted, so either bPh3xg2-g1= or wPh was waylaid. In any case, all captures are accounted for. wPf promoted. Easy to see that White cannot have just played g2-g3 or f2xg3 or d2-d3 or axb6. So must have bPb4 rather than b5, allowing for White to have just played Sb5-a7 or b5-b6. If any of the "retro-dressing" White pieces e.g. Sa8 are removed, then White might have just played g2-g3 or d2-d3. At least the retro-dressing units have no possible last move (& wSa8 wBb8 have not just promoted), so there is some craft to their deployment. (2024-03-11)
A.Buchanan: bPg6 blocks a cook so must stay there, but can shift bPe7 to d7 (allowing the removal of wSa8 or wBb8) or to b3/b7 (allowing the removal of all three White officers: wSa7a8 & wBb8.) Maybe that's worth doing? (2024-03-11)
Yuri Bilokin: Thank you for the detailed analysis. Perhaps my poor view will allow you to get an optimal starting position. (2024-03-11)
Henrik Juel: a) 1.Sh1-f2 Qf1*f2 + 2.Kh2-h1 0-0-0 #
b 1.Sa3-b1 Ra1*a4 2.Sh1*g3 Ra4-h4 # (2024-03-11)
Henrik Juel: C+ Popeye 4.61 and analysis (2024-03-11)
A.Buchanan: I had wanted to keep to the spirit of P0003659, in which may be the author wanted to have a bunch of White retro-dressing that could not retract. But going back to the first version P0003659, the White position is much cleaner. So following Yuri being bothered by a horse, I am going to change the diagram here from NBr5/N1p1p3/1Pqp2p1/2bb4/pp6/n1pP1rP1/1PP1P2k/R3KQ1n by removing 4 white units. Hope this is agreeable to all (2024-03-13)
more ...
comment
Keywords: Cant Castler, Castling (wg)
Genre: h#, Retro
FEN: 8/rpp2p2/1Pqp4/2bb4/pp6/n1p2rP1/1PP1P2k/R3KQ1n
Input: A.Buchanan, 2024-03-06
Last update: A.Buchanan, 2024-03-13 more...
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