[Retros] Cooking a famous AP-problem?

[Rol, Guus]

Yesterday my brain must have been short-circuited for a while trying to
sell you standard "AP type Petrovic" for the move turnover type "AP
after Keym". Fortunately this doesn't affect the crux of the story but
I'll correct it here for the sake of clarity.
 
Guus Rol.
 
(correction of yesterdays entry)

	Dear retro-friends,
	 
	Another chapter in my discussion of retro-strategic principles
is this famous problem by Gert Rinder. Now, I haven't voiced my concerns
on the foundations of AP-logic here (yet) and I won't be doing so at
this point. I'd rather focus on 2 aspects of this composition:
	 
	(1) the post factum principle in the move choice for AP problems

	(2) how can the automatic repetition rule cook this problem - to
create an even better one!
	 
	Author: Gert Rinder
	Position: r2bk3/p1Rpp3/P1p2p2/KpP2P2/1P2p3/1P6/P7/8
	Author stipulation: Draw (AP type Petrovic)
	My stipulation: Black wins!
	 
	Starting from the second aspect I suggest this solution: 1.cxb6
e.p. (requiring justification) axb6+ 2.Kxb6 Pa1R 3.Kb7 R1xa6 4.Rc8
(first time) R8a7+!! 5.Kb8 Ra8+ 6.Kb7 (second time) R8a7+ 7.Kb8 Ra8+
8.Kb7 (third time!); if you know PB-R309, you know what comes next. The
position can't be considered a draw since there is no proof that the
"same" position occurred thrice! Continuing play however - by whatever
move, e.g. R6a7 mate - proves prior black castling right absolutely, and
thereby proves the e.p. right a posteriori.
	 
	Now there are several ways to argue against this approach - we
don't want this automatic draw convention, it didn't exist at the time,
this is a strange mix of AP and PF (not a good objection), etc - but all
objections overlook the angle of having just created a beautiful new
solution to a famous AP-problem. Not only does it contain all of the
content of the previous one - the original solution becoming the try -
but it adds a new element as well which is not readily available in most
AP-compositions. I couldn't find another existing AP-problem cooked
through this procedure, but I could find some that will be easily cooked
by the 50-moves rule if it ever became rationalized and automatic. It is
a characteristic trait of AP-problems that short AP-solutions can be
affirmed or refuted by long "virtual" variants.
	 
	Now back to point (1). In one of my previous posts I introduced
the (rather arbitrary) concept of "game enforcers". This is a good case
for demontrating what I mean by that. The principle behind game
enforcement is that "a PF-solution continues under most conditions
unless can be shown that it stops". One of the reasons is that PF
implies that all choices from all "acceptable pasts" are available
simultaneously. White may castle long if he can, he may castle short if
he can - his choice is arbitrary even if the castlings are mutually
exclusive. In Gert Rinders problem the question is the choice between 2
pasts: (I) a past in which white is stalemated in the diagram (II) a
past in which e.p. is legal and can be justified a posteriori. PF logic
says he can chose either one of them and therefore must chose the one
that will leave him a move. Stalemate is the absence of even a single
option to move. PF-logic shows that the stalemate option need not be
accounted for by retro-variants. So indeed, white starts and black wins
in this composition.
	 
	Note: I use the common descriptor PF here, but I'd rather use PA
(Post Actum) for its major component. Left for another post.
	 
	Guus Rol. 

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