[Retros] On the Jumanji convention

[Rol, Guus]

Alexander's first point is similar to my discussion of "rights
terminology" of about a year ago. My approach was (and is) to separate
the terminology connected to the proof game domain from the terminology
in the action (solution) domain. The "right to castle" in a proof game
is always beyond debate since the proof game is fully determined. For
the RS action conventions I favored the more negotiable descriptor
"castling license", as subject to withdrawal as you drivers license.
"Castling permit" and "castling privilege" may be equally attractive
substitute terms. The basic point is that the "proof game system" acts
as a verification system for the "solution action system" - there must
always be a proof game - but they need not run with identical properties
on identical rule sets. In fact, article 16 quite cleverly avoids
mentioning "castling rights" in clause 1 using "permissions" instead.
This leaves room in article 3 to interpret the "right to castle" as a
proof game property. After all, the partial objects in PRA consist of
precisely those proof game groups where "castling rights" or "e.p.
rights" are uniformly present. Only the RS part in the closing sentence
of clause (3) which reads "the party exercising this right first"
indicates that the separation of "rights" and "permissions" was not of
the highest priority to its scribes. Or wasn't understood in the first
place.


The second point in Alexander's comment is an old favorite of his. It is
true that FIDE should make an explicit allowance for the full analysis
of all cases (which he calls CRAC). But even CRAC must be customized to
control the administrative rules (repetitions and 50M). For one, some
proof cases would certainly be immediate draws in the diagram position,
and many others might draw after a reversible key-move for the same
reason. Once you enter the denial or subordination of these attributes,
you cannot avoid creating an administrative article 16 look-alike.
Alexander is right though when he detects vagueness in article 16 "what
does it mean to take into account a convention ..". The expression "take
into account" is not accesible to logical evaluation and must be avoided
in a pretty formal article. Fortunately we all know what is meant since
we have been around for so long, but only for that reason! As I do not
believe that CRAC can effectively avoid the reduction of "all cases", I
can sympathize with the intent of article 16 part (3) to eliminate the
"undesirable histories". The definitive justification can be found in
the creative retrograde potential of article 16 compared to CRAC which
is about a million to one. Allowing for CRAC should therefore not lead
us into the temptation to reject the PRA and RS (and AP) logics.
Finally, Alexander made a keen observation on the squaring of the
"partial" attribute. "Partial Retrograde Analysis" is not now the
"retrograde analysis of the parts" but it is only the "partial
retrograde analysis of the parts". PRAP if you like.


Guus Rol.



-----Oorspronkelijk bericht-----
Van: retros-bounces at janko.at [mailto:retros-bounces at janko.at] Namens
Alexander George
Verzonden: maandag 5 januari 2009 17:14
Aan: The Retrograde Analysis Mailing List
Onderwerp: Re: [Retros] On the Jumanji convention

For some other thoughts about Article 16 and Werner Keym's discussion of
it, you might be interested in my recent post in ChessProblem.net:

http://chessproblem.net/viewtopic.php?f=10&t=290

Regards,

Alexander George

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