[Retros] 50 moves rule

[raosorio at fibertel.com.ar]

Seth Breidbart  wrote,

It seems to me that the underlying issue is the definition of 
"position". Is it a photograph of the pieces on the board? That plus 
information as to whose move it is? That plus information as to who 
might be allowed to castle (and on which side) in the future? 
(Consider a position in which White has not castled, his King and 
Rooks have not moved, but it can be proven that there is no future 
play which involves White castling; how does that count?) 
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Good point. i think that "if it can be proven that there is no future play which involves
 White castling" then  white has already lost its  castling right (understanding
right as  a real chance to do  it). This  is  to avoid the "bookkeeping" approach
as  Guus set.
The same apllies to e.p.  capture if  the  capturing pawn is pinned. There  were no
real  chance to make the  e.p.  capture so  this position should count as "no  e.p. 
capture right".

Roberto Osorio