[Retros] PCCC meeting decisions: comments, history
liskov at im.bas-net.by
liskov at im.bas-net.by
Sun Oct 25 08:44:25 EDT 2009
1. In my opinion, this current wording of Art.16(3) of the Codex (Rio
de Janeiro, Oct 2009) is a great leap in "justifying" controversial
retro-genres. It is a very pleasant surprise for me that Werner Keym
(in cooperation with other experts) has managed to push this correction
of Jurmala's 2008 formulation (which has finally justified PRA as an
uncoditional orthodox genre!).
2. Frankly speaking, I'm not fully satisfied still: AP does remain
a conditional genre whereas it deserves to be (and can quite easily be,
at least in its classic form a la' Keeble - Petrovic) incorporated in
a naturally extended genre hierarchy in a similar way. Besides,
retro-strategy is too narrowly restricted to incompatible castlings.
Well, let these tasks stay for the future.
3. Btw, since RS is now (after Jurmala) strictly defined, in all SIMILAR
but DIFFERENT cases (mainly in fairy retro) I offer, once again, to use
the term "PF" (post factum) instead of it ("subordination" also suits):
RS is a particular case of PF but, unlike the latter, it doesn't need
to be stipulated expressly.
4. Several details on the pre-history. The unlucky consequence of
Jurmala's wording of Art.16(3) overlooked by its authors and explained
in the proposal of W.Keym was indicated in my article
„Retrovariants in helpmates with two white castlings", `StrateGems’,
where I wrote: „... there are two dozens of h#-problems ... that possess
formally the features of pRA (no last move preserves both castlings) but
whose solutions do not depend on the answer: which castling is legal.
These problems would become unsound under pRA; thus, we cannot reinterpret
them retroanalytically" (p.159). Two such examples are reproduced in the
article. Of course, this elementary fact was well known long ago (but
perhaps not in written form?).
In this forum I first mentioned such an undesirable consequence in my
mail of 19 Sep 2008 (illustrating this by the problem P0534191 of Orlik).
That time WK and I began to intensively discuss this situation.
5. MOST importantly, the very idea to use an appropriate ordering of
controversial genres for the recognition by the solver of the genuine
genre of a problem was proposed by me in the article
„An order in controversial retro-genres", `Shakhm. Kompoz.’, 1993,
No.6, 58-60 (in Russian).
Later on, I described or mentioned this idea several times in the Retros
mailing list (for the first time in my mail of 4 Dec 1996). This global
"hierarchical" proposal included 4 genres (in the prescribed order):
1. AL(=ad libitum; "typ Keym") 2. AP(=a posteriori)
3. PF (subordination) 4. PR ("typ Oeffner"). Now,
A PROBLEM IS ASSUMED TO BELONG TO THE LEAST GENRE IN WHICH IT HAS
A (full) SOLUTION!
W.Keym significantly simplified this natural idea (now I think that the
differentiation between AL and PR inside PRA is NOT essential indeed...).
Apparently, of particular attractivity for adherents of PRA is the fact
that such a suitable hierarchy begins with PRA rather than with RS;
for me, on the contrary, this does not matter: any order that ensures
identifying properly the genre of a controversial problem in the process
of solving is equally acceptable.
Joost de Heer <joost at sanguis.xs4all.nl> wrote:
> For retro-composers the following is of importance:
> "The last sentence in paragraph 3 of Article 16 of the Codex was modified."
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