[Retros] PRA & RS: Jurmala-2008 vs Piran-1958

[Valery Liskovets]

Dear retro-friends,

(Retro-)Article 16 of the Codex was radically modified at the
51st Meeting of the PCCC in Jurmala (Latvia) on Sept. 6, 2008
(mostly due to efforts of W.Keym and b.ellinghoven). See
 http://www.saunalahti.fi/~stniekat/pccc/codex.htm#b19

Valery L.

"Article 16 - Castling and En-passant capture

(1) Castling convention. Castling is permitted unless it can be
proved that it is not permissible.

(2) En-passant convention. An en-passant capture on the first
move is permitted only if it can be proved that the last move
was the double step of the pawn which is to be captured [20].

(3) Partial Retrograde Analysis (PRA) convention. Where the rights
to castle and/or to capture en-passant are mutually dependent, the
solution consists of several mutually exclusive parts. All possible
combinations of move rights, taking into account the castling
convention and the en-passant convention, form these mutually
dependent parts. In the special case where White's right to castle
excludes Black's right to castle (and vice versa), an alternative
is possible: the party exercising this right first is entitled to
castle (Retro Strategy (RS) convention).

(4) Other conventions should be expressly stipulated, for example
if in the course of the solution an en-passant capture has to
be legalised by subsequent castling (a posteriori convention AP)."