In the thematic retroplay, i.e., the retroplay that must take place
before the position unlocks (here, when the BK is free to retract),
of a fully realized example of the Homecoming Theme, six uncaptured
units (one a Knight that unpromotes and, as a P, accounts for three
of those uncaptures), together with four units supplied in the diagram,
must return permanently to their respective home squares, in the course
of which the WK must retract to a corner square and subsequently uncastle.
Only 18 units need appear in the diagram.
Defined terms, for simplicity of reference:
The thematic retroplay has the following features:
The following four compositions address the theme:
1 - Niels Høeg
Magasinet 11/1, 1942 (January 11th?)
10+9. Retract 13.0 moves (White starting)
2 - H. Goldsteen
Die Schwalbe, 1988
9+8. May White move?
3 - H. Goldsteen
11+8. White mates in one
4 - Thomas Volet
10+8. How long must the N have remained at d8?
The Hoeg Progenitor presents the Unpromoting N in the diagram without
features (1) and (2), presents feature (3) in the diagram, doesn't show
feature (5), and partially displays feature (6), but nevertheless clearly
anticipates the general theme. Goldsteen 1988 does not show feature
(3), and partially displays feature (6). Both Goldsteen 1989 and Volet
1997 show all features (the latter without stipulation as to which color
has the move).
Provided by Tom Volet, as developed through correspondence with Henrik