[Retros] Singular PG

[raosorio at fibertel.com.ar]

Dear retro friends,

This is my first experience using the list. Hope I'm doing it Ok.
I want to put into your consideration an idea for a new type of
PGs proposition.

The idea is based on defining the group of existing chess stipulations with the
following common characteristics: the moves as such are geometrically orthodox,
i.e.,  they are as visible and acountable as in the orthodox chess. For instance,
if the original b1 knight is at e7 it required minimmum 3 moves in any of these
stipulations. If it has to capture on e7 and come back, it requires 6 moves.

Let's call this group "Geometrically Orthodox Stipulations" (GOS). It includes,

* Orthodox
* Madrasi
* Koko
* Single Box Type 2
* etc, to be defined
(of course stipulations like Circe, Anticirce,Undernatch, etc, are not included)

Each one of these stipulations is defined by a restriction of the moves posibilities under
well defined circumstancies. On the other hand, the restriction makes feseable some
king moves wich would not be posible in orthodox chess (when the restriction is vanishing
the check power of a man). 

This particular effect (say, the potentiation of the restriction) determines that some diagrams
are reachable in n moves only under a unique GOS stipulation . Let's cal this particular cases

PG in n moves Singular on GOS

(this means that there is only one Stipulation on GOS that makes posible to reach the
position in n moves, and the sequence is unique)

Stipulations wich are just particular cases of the orthodox one (stafetenschach,
single box type 1,etc) are not included in the list because they have no potentiation,i.e., they
will be always orthodox.

So, the solutionist has to find the proper stipulation  and the sequence. An example,

r1bqBbsS/ppppp1pk/8/7p/8/4P3/PPPP1PPP/R1BQK1SR
PG in18 single moves Singular on GOS

Solution:
Madrasi Stipulation
1.- Nc3,Nc6 2.- Nd4,Ne5 3.- Ng6,Ng7 4.- Nxf7,h5 5.- Nxh8,Kf7(the key)
6.- e3,Kf6 7.- Bd3,Kg6 8.- Bxg6,Kh6 9.- Be8,Kh7

Analysis:
Of course, this PG has no orthodox solution (Natch tested)
The key is the capture of the f black pawn. Analyzing the paths
of white knight and bishop, it is clear that the capture is only
posible on f4 or f7. After getting crazy a bit, the solutionist will
conclude there is no chance to do it on f4 due to sequence problems.
On the other hand, the capture on f7 by knight or bishop would
interrupt the black king path (orthodox). However, the pawn has to be
captured on this square, and  the capturing man has to be paralized
to get the king free, so the stipulation answer is :Madrasi.

This ilustrates the solving method:  trying the orthodox stipulation first,
one finds the dificulty and this will suggest the necesary stipulation. 

This way,  the solutionist has all he needs to face the problem:

* A closed set of chess stipulations as potential candidates.
* A diagram and n moves available.
* A method: trying first the orthodox way, the difficulty will appear and
  he has to identify the necesary stipulation to solve it.

Here I propose another example to be solved by the retro friends,

rnb2bnk/pppp1p2/3p4/8/7p/2N5/PQP1P1PP/1RB1KBqR
PG in 24 single moves Singular on GOS

I will appreciate all the comments on this idea wich I consider is still a rough draft.
It will be specially interesting to see how to complete the GOS stipulations list.

Thanks in advance to everybody and best regards,
Roberto Osorio