[Retros] Programs for Solving Retro Problems

[Mark Tilford]

On Sun, Aug 24, 2008 at 2:16 PM, Mario Richter <mri_two at t-online.de> wrote:


> Here the rule seems to be something like "If a king is in check

> by two enemy pieces, and none of this enemy pieces can interfere

> the checking line of the other piece, than the position is illegal."

> This works in most positions, but forgets the case, that one

> of the enemy pieces may change his shape while retracting -

> by unpromotion.

>

> e.g. 5QN1/8/5k2/8/8/8/8/7K (w: Qf8 Ng8 Kh1   b: Kf6)

> or   5R1B/8/5k2/8/8/8/8/7K (w: Rf8 Bh8 Kh1   b: Kf6)

>

> 'Retractor' rejects the above positions with the message:

> "Error: This position places your king in an illegal

> double check."


Does it also run into trouble with detecting an un-en passant?