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=

Duplicate Diagram: P1187070

1) R: 1. Kc5xDd6 Dd7xDd6, dann 1. Dc6 Dxc6=
2) R: 1. Kc5xBd6 c7xDd6, dann 1. c6 Dxc6#

R: 5899. Kg2xTh1

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

1. Kf3 [+wBe3] e4 2. Kxe4 [Kf7] [+wBf3] f4 3. Kg6 [+wBf7] f5+ 4. Kxf5 [Kh8] [+wBg6] f8=D#

R: 1. Kf6xBg6, dann 1. ... Kh8 Kf7, dann R: sBh7xBg6, dann 2. ... g7#

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.

1. Kb2 2. Kc3 3. Kd4 4. Ke5 5. Kf6 6. Kf7 7. Ke8!= (nicht mehr orthodox, d.h. Marscirce)

Duplicate Diagram: P1233049, P1233544

* 1. ... Kf3 2. Ke1 Ke2=
1. Ke1 Ke3 2. Kd1 Kd2=

vgl. Nixon 1953 (P0575588)

a) * 1. ... Kb6 2. Kb8 Kb7=
1. Kb8 Kb6 2. Kc8 Kc7=
b) 1. Kb7 ... 2. Ka6 Kb6=
b) 1. ... Kb6 ... 2. Ka7 Kb7=
c) * 1. ... Kd6 2. Kd8 Kd7=
1. Kd8 Kd6 2. Kc8 Kc7=

1) 1. Kb2 Kd3 2. Kc1 Kc2=
2) 1. Ka2 Kc3 2. Ka3 Kb3=

Echopatts. Preisrichter war Juraj Lörinc. vgl. Nixon 1953 und Kniest 1963

1. Kc3 Ka2 2. Kc2 Ka3 3. Kb1 Kb2=
1. Kc4 Kb2 2. Kb5 Kc3 3. Ka4 Kb4=
1. Kc2 Ka2 2. Kb1 Kb3 3. Kc1 Kc2=
Im Satz ist Weiß patt. Der schwarze Anzug ist illegal.