[Retros] The Problemist March 2008

Joost de Heer joost at sanguis.xs4all.nl
Sat Mar 29 12:25:03 EDT 2008

Norbert Geissler schreef:

> Hello all,


> as it was published in the fairy section (I suppose),

> the authors didn't have any retro-analysis in mind.

> Just solve beginning with the given position and enjoy

> this little miniature ...

Footnote 18 from the latest codex:

18 Retroanalysis does not apply to illegal positions, except for the
purpose of determining that they are illegal. It also does not apply to
fairy compositions unless it is essential to the content of the composition.

Whether one should apply retro analysis to fairy positions is of course
food for debate (it'd probably be a nightmare to construct a proofgame
using imitator and maximummer to reach the diagram position), but if the
proof that castling isn't allowed as trivial as in this example, in my
opinion it should at least be mentioned that retro analysis isn't applied.

I enjoyed playing through the solution (I'm horrible at solving, so I
let a computer do this for me ;)) by the way.

One other question on footnote 18 though: Does this imply that one can
always castle and capture ep in the diagram position when the position
is illegal? Retro analysis isn't applicable, so I don't have to prove I
can still castle, or proof that the last move was indeed the needed pawn
double step....


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