Henrik Juel: minor dual in forward play
1.bxc6ep+ Db5 2.DLxb5+ Tc4 3.LDxc4#
1... b5,bxa6 2.Kxb4+ Tc3 3.Txc3# (2022-07-01)
Henrik Juel: Last move must be c7-c5, enabling Tc2 to reach g8 in just three retractions (2022-07-01)
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Henrik Juel: Accprding to Retrograde Analysis, 1915, the intended solution does not involve adding pieces as such, rather:
Black retracts the illegal move Pd2xSe1=S+ (exposing Kb2 to a selfcheck from Dh2)
and instead pays the penalty of a king move, Kxc3 (only possibility)
Then White mates by 1.Dh8# (2023-04-13)
Mario Richter: @Andrew: Why did you remove the "illegal position" keyword?
Instead of removing this keyword, I suggest to remove the "Add pieces" KW ... (2023-04-14)
A.Buchanan: Hi Mario, yes good question. I removed "Illegal position" from some genuine "Add pieces" compositions, because it suggests some error in the composition. But on reflection, I think I will put the "Illegal position" back for these, and instead edit the description for the keyword.

Now this problem was in fact incorrectly marked as Add pieces. It's one of Dawson & Hundsdorfer's canonical examples of an "implausible" joke. I.e there is no reason why the intended retraction is the right one, except that it works. These too should be marked as illegal position. Sorry for all confusion (2023-04-14)
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Gerd Wilts (2001-10-17): The retro play given in the solution serves only to justify that it may indeed be White's turn. The forward play indeed starts with 1. Bf7. The idea of TRD was to compose a problem which is legal but in which one of the knights must be a promoted pawn. TRD called this an "obtrusive Knight".
AB: Solution (& keywords) are from a different problem. Solution is 1 Bf7 etc. (2001-10-16, hidden)
Gerd Wilts: The retro play given in the solution serves only to justify that it may indeed be White's turn. The forward play indeed starts with 1. Bf7. The idea of TRD was to compose a problem which is legal but in which one of the knights must be a promoted pawn. TRD called this an "obtrusive Knight". (2001-10-17, hidden)
AB: Oops it would be neat to have feature to delete my tired remark. :-) (2001-10-17, hidden)
Henrik Juel: C+ Popeye 4.61 (2020-10-31, hidden) more ...
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Hans-Jürgen Manthey: Nachdruck SExpress 1.Mai 1947 S.41 Nr.33 (2022-10-15)
E.Gon: In this line! Where is this mate? After 2.Dh8 Txh8! (2009-03-16, hidden)
E.Gon: Oh, sorry! It was my fault! 1...0-0-0? :) (2009-03-16, hidden)
Henrik Juel: C+ Popeye 4.61 (2022-04-26, hidden) more ...
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Henrik Juel: 1.Td1, not 1.0-0-0? -1... c7 -2.Kd2 Tg3 etc. (2004-03-09)
Henrik Juel: C+ Popeye 4.61 and analysis (2022-05-07, hidden) more ...
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Version in der 'Aarsskrift' 1935 innerhalb eines Artikels von K. Hannemann "Et Tema Fra den Retrograde Analyse". Im Original wDg4 statt h3 und wBh3 statt h4.
Henrik Juel: 1.exf6ep+. Not -1... a6?, requiring 3 black captures on light squares (incl. orig. Lf1); but missing orig. Lc1 was dark-squared. (2004-03-08)
Henrik Juel: C+ Popeye 4.61 and analysis (2022-06-11)
Hans-Jürgen Manthey: mögliche Zugfolge:
1. f2-f4 d7-d5 2. c2-c3 d5-d4 3. c3xd4 c7-c5 4. h2-h4 c5-c4 5. b2-b4 Lc8-d7 6. a2-a4 Ld7-b5 7. a4xLb5 Sb8-a6 8. Th1-h3 Sa6-c5 9. d4xSc5 Sg8-f6 10. d2-d4 Sf6-e4 11. c5-c6 Se4-g3 12. Lc1-d2 Se4xLf1 13. Sb1-c3 Sf1-g3 14. Sc3-a4 Sg3-e4 15. c6-c7 Ke8-d7 18. Sa4-c5+ Kd7-d6 19. Sc5-a6 Se4-c5 20. b4xSc5+ Kd6-e6 21. Ld2-a5 b7-b6 22. Sa6-b8 b6xLa5 23. Th3-e3+ Ke6-f6 24. Te3-e5 Dd8-c8 25. Dd1-d3 Dc8-a6 26. Dd3-h3 Da6-b6 27. Ta1-a3 Db6-c6 28. Ta3-g3 Dc6-d6 29. Te5-d5 Dd6-e6 30. c7-c8L De6-d6 31. Lc8-f5 Dd6-c6 32. Sg1-f3 Dc6-b6 33. Sf3-e5 Db6-a6 34. Se5-g6 Da6-b6 35. Sg6xTh8 Db6-c6 36. Tg3-g6+ h7xg6 37. Ke1-f2 Dc6-d6 38. Kf2-g3 Dd6-e6 39. Kg3-g4 De6-d6 40. Lf5-c2 Dd6-c7 41. b5-b6 Dc7-e5 42. f4xDe5+ Kf6-e6 43. Kg4-g5+ f7-f5 und nun :
1. e5xf6ep+ Ke6xTd5 2. Dh3-d7# (2023-02-24)
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