[Retros] Thoughts about P0000230

[Guus Rol]

Somebody will be able to supply you with the proper reference but a change
was made many years ago to include castling as a 50-move breaker. Strangely
enough, the loss of castling right by moving king or rook does not count as
such, even though the effect in terms of "theoretical reversibility" is the
same. Also note that the loss of e.p. right does not delay the start of a
50-move sequence by 1 move.

There are 2 common interpretations of the 50-move convention: (1) a position
draws automatically after 50 "reversible" moves (2) a position draws in or
following a diagram after 50 or more "reversible" moves have been proved.
The second interpretation allows over 50 "reversible" moves to occur in the
past of a diagram, but draws in the present. In my opinion, only the second
interpretation conforms to the current convention which disqualifies all
problems based on the first one. Much to the dislike of composers who tend
to ignore this possibility.

 (Un)Fortunately, the example you picked seems incorrect by either
interpretation. Under the first interpretation, you can't reach the diagram
in a proof game ending with the move taken back, simply because it would
have drawn by what I recently described as "premature termination". Under
the second interpretation, your attempted dual is irrefutable. There is
absolutely nothing wrong with having 60 "reversible moves" and getting a
draw after taking one move back. Note: a retraction occurs in the future of
a diagram and delivers a new diagram, the original move occurred in the
past.

Obviously, this evaluation depends on the correctness of the content you
presented; I didn't verify it! The only thing that could have been on the
author's mind is the idea that the game ended after 50 "reversible" moves
and accidently one more move was played and subsequently retracted. For that
to occur, one would need to assume that it is OK to play  an ILLEGAL move to
reach a diagram. I do not know of any convention allowing for such an
approach. Even Roberto Osorio's MDR which gives room to many types of
illegal moves, does not permit playing past a termination state! Concluding,
I cannot find any genuine retro justification for this creation apart from
the fact that almost any excuse will do to pay tribute to one of the great
retro-composers, Nikita Plaksin!

Guus.
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