[Retros] recent improvements

[Mario Richter]

Andrew wrote:


> However, Francois Labelle's (& Mario Richter's?) programs have not spoken

in

> this discussion. Tasks of this kind ought to be tractable in the same way

> that massacre positions proved to be. Basically, ignore any move where a

> promotion cannot be achieved in the number of moves remaining.


The problem is, that the more degrees of freedom (in the case of
MPGs non-capturing moves, in the case of 'mate by promotion'  moves
that do not advance the thematical pawn) you have,
the longer the search will take.

This could be observed in the case of K+K-MPGs, were the 33 plies
case could be completely investigated in less than 10s, while the
next step, 34 plies, already required approx. 10min.

Nevertheless, at least up to 10 plies Francois Labelle surely
knows the answer.
(s. www.cs.berkeley.edu/~flab/chess/statistics-positions.html )

Just out of curiosity (and because Andrew asked for it) I let my own
program run.

Computing all games, that end with mate by pawn promotion,
required for:
  -  9 plies  2s
  - 10 plies 42s
  - 11 plies 1h 50min

The way my program works there is some extra time needed for
post-processing the result sets to find the the uniquely
realizable games.

Here my results:


Realizable in 9 plies
 - Pb7xc8=R
 - Pc7xd8=R
 - Pg7xf8=R
 - Pc7-c8=Q
 - Pb7xc8=Q
 - Pc7xd8=Q
 - Pg7xf8=Q

Realizable in 10 plies
 - Pg2xh1=R
 - Pd2-d1=Q
 - Pf2-f1=Q
 - Pf2xe1=Q
 - Pg2xh1=Q

Realizable in 11 plies
 - Pc7xd8=N
 - Pe7xd8=N
 - Pe7xf8=N
 - Pg7xf8=N

 - Pe7-e8=B
 - Pe7xf8=B

 - Pc7-c8=R
 - Pd7-d8=R
 - Pe7-e8=R

 - Pb7xa8=R
 - Pd7xc8=R
 - Pd7xe8=R
 - Pe7xd8=R
 - Pe7xf8=R
 - Ph7xg8=R

 - Pe7-e8=Q
 - Pb7xa8=Q
 - Pd7xc8=Q
 - Pd7xe8=Q
 - Pe7xd8=Q
 - Pe7xf8=Q
 - Pf7xe8=Q
 - Ph7xg8=Q

Regards,

  mario