[Retros] Two little SPG-challenges

[Mario Richter]

Dear retro fans,


Noam Elkies wrote:

> > Second challenge:

> > 

> > Both proof games contain a rather paradoxical

> > element (at least I consider them that way).

> > Can you construct longer proof games (not

> > necessarily of the "At-Home"-type), which show

> > the same element?

> 

> I'm not sure what you mean here.


Because I didn't want to give hints to the solutions, 
I have (intentionally) been a little bit unclear here.


> I see different paradoxical elements in the A and B

> solutions, both of which have been featured many times

> in longer proof games, so can't be the one common element

> you have in mind.


I did not mean that A and B share a common element.
Sorry for being not clear enough here. 


In an SPG the goal is to reach the final position
*as fast as possible*, so I call elements of the solution, 
which seem to be counter-productive with respect to 
that goal, "paradoxical".


> Position A: rnb1kbnr/pp1ppppp/8/8/8/8/PPPP1PPP/RN2KBNR

>             SPG in 7.5 moves  (13 + 14) 


In the solution of Pos. A the paradoxical element consists of
the fact that the white King - the *slowest* of all pieces, 
makes 6 out of the 8 white moves.

So I call this challenge "Busy-King-SPG":

In the final position of an SPG one king is occupying it's 
original square.

Construct an SPG (with a unique solution), where this king 
has made as many moves as possible.



> Position B: rnbqk1nr/pppppp2/8/8/8/8/PPPPPPP1/R1BQKB2

>             SPG in 7.0 moves  (12 + 13)



In the solution of Pos. B only one piece of each side
does all the work, so I call this a "Lazy-Spectators-SPG".

Here the question is:
What is the longest possible SPG (with a unique solution),
where in the whole game each side moves only one of it's
pieces?


greetings
  mario