[Retros] No (1+1) SPG at x=5

[CAILLAUDM at aol.com]

Hello Francois,



> Some of the computer-composed problems that I announced earlier appear in

> Problemesis 38.

> 

> [R142a-b] vertical symmetry

> [R143] at-home (most depleted)

> 

> The rest is delayed because of my desire to publish the best problem for

> each task.



"Best" is a sometimes subjective matter. There can be several "bests" 
depending on which criteria are applied...


> 

> For the (1+1) SPGs, I want to investigate all the diagrams with few

> solutions. There's a small chance I can find one with independent

> solutions.

> 

> For the SPGs enabled by A1.3, I want to investigate if there are any with

> more pieces on the board.

> 

> For the stalemate SPGs I'm torn, because Popeye solves the (7+3) one at

> x=5 in 77 min, and the (4+1) one at x=4 in 12 min. So the latter might be

> an easier problem, and it's theoretically more interesting (by being the

> only stalemate SPG at x<=4), but of course its diagram is less furnished.

> 


"Easier" is different from the point of view of electronic or human solver. 
For the human, it is more confortable to have more furnished diagrams, present 
pieces being clues to the riddle. So, R142 and R144 can be solved, though 
certainly more difficult than problems with the same length and less captures. 
R143 is "humanly" very difficult, and I think it can't be solved except investing 
enormous time (which I will not try). 



> For the at-home AND mirror-symmetric SPGs, I thought it had nothing to do

> with massacres and that there must be better examples of this task at low

> plies.

> 

> So instead I published a task where massacre probably gives the best

> example:

> 

> [R144] fullest at-home position with no pawns

> 

> A short note about computer testing: problems [R142] and [R144] have been

> independently verified by Popeye. [R143] was computer created, but not

> computer tested. Personally I think that the problem shouldn't be

> considered C+, but Christian chose to publish it as C+. I wonder what's

> the right thing to do in this case. For [R143] everything was done to a

> very high standard, but I would like to have the right to be sloppy with

> my programming in the future.

> 

> 


Well, we cannot be absolutely sure that there are not undiscovered bugs in 
Popeye, Natch or Euclide (and indeed some were found in the past), nevertheless 
problems tested by them are admitted "C+".
Until now, your programming has proved rather performing, what gives a high 
level of confidence in your results.

Best,
  Michel

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