[Retros] En passant chess : self-defense

Rol, Guus G.A.Rol at umcutrecht.nl
Thu Mar 29 04:56:11 EDT 2007

Hi Pascal,

I am worried about some of the metaphors, but Andrews metaphor with the
advanced combat unit trailed by supply wagons seems OK. No collapsed
time, no virtualized move series - except on captured Kings which is a
isolated issue. In your example the Rook captures the Queen and keeps it
imprisoned. It is obvious that prisoners must be considered powerless so
the Queen cannot take the Rook in turn. Another unit though could
capture the Rook e.p. - presumably by taking its trailing supply wagons
- while releasing its prisoner, the white Queen.

Note that the mataphor also holds when the Rook is captured directly,
e.g. BxRe1. The imprisoned white Queen would be restored if e1 were
available but it is not. As in Circe the Queen disappears.

There is however one situation which is decisive for the acceptance of
the supply wagon metaphor in relation to en-passant chess. It is the
reversed application of the rule, en-passant capture followed by direct
capture. Example: wQe8-e1, bRa5xe5 e.p., wBd6xe5. Does this release the
white Queen? The supply wagon metaphor would suggest yes since there is
no difference in its application to the moves Bd6xe5 and Bd6xc5 e.p.! In
my view this extension is natural but it may not have been the idea of
the inventor of e.p. chess. If the reversed version is rejected, the
supply wagon metaphor should be refined or rejected as well. Also note
that reversed e.p. calls for a decision on the duration of the
imprisonment. In contrast to the immediate e.p. reply, a direct capture
can be delayed arbitrarily. Will the Queen still be freed when Bd6xe5 is
played 10 moves later?

I hope Andrew won't mind that I'm running away with his metaphor. He is
welcome to jump in with his own story! I have used it to illustrate the
complexities of rule-making.

Guus Rol.

> -----Oorspronkelijk bericht-----

> Van: retros-bounces at janko.at [mailto:retros-bounces at janko.at]

> Namens Pascal Wassong

> Verzonden: woensdag 28 maart 2007 18:46

> Aan: The Retrograde Analysis Mailing List

> Onderwerp: [Retros] En passant chess : self-defense



> Hello,


> with the rules I have seen on the ep chess, it is not made

> clear to me that a piece being captured cannot take en

> passant the piece that wants to capture it.


> For example : wQe1, bRe8 : can Re8xe1 be stopped by Qe1xRe2 ?


> In some metaphors given on this list, that should be possible.


> If this is possible, is mate possible ? I think so : the

> King must be threatened by a Knight, or by a piece being in

> contact with the King.



> Having fun,

> Pascal


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