New restriction element

[pazeinat]

Suggesting a restriction on the nature of the piece that moves to gives the mate, or the square on which the black/white kings are being mated.
Examples:

1. Restriction (mate by rook); Restriction (mate by w Pb2) etc.
2. Restriction (bK mated on a2)
   The format of this can be changed as seems applicable

[dturevski]

The concept sounds super useful.
Having an option to constraint the solution is very exciting.
Constraint Ply 10 PieceType LE
This kind of machinery.

[thomas-maeder]

I am trying to understand this feature and its super usefulness.

• Is it just another fairy condition? If yes: can you provide example problems?
• Is it something else? If yes: what?

[pazeinat]

I think it is part of the stipulation. I composed something which I'll attach here: Ser-h#36 mating move by wPb2
Einat & Costeff

[dturevski]

The feature I had in mind was to allow the user to inject additional shortcuts to the popeye's solving pipeline.
That, for instance, would allow some new fairy conditions.