[Retros] En Passant Chess (Noam Elkies)

Noam Elkies elkies at math.harvard.edu
Tue Mar 20 15:59:41 EDT 2007

> In your variant of En Passant Chess allowing restoring of captured

> pieces, we could think of pieces just like billiard balls. [...]

I don't think this visualization works, because the opponent may
have a choice of which billiard ball to activate, and indeed
may choose to activate none if the opponent's piece stopped
short of its target (1 d3 g6 2 Qb3 Ba6 3 Q-->f7: maybe Black
starts the Ba6-ball rolling, but then decides not to if the Queen
stops at e6).

> What about multiple captures? They are really crazy.....

Right, as with Orphans and more complicated recursive rules.
It is not immediately clear to me whether and how easily
a paradox might arise.

A nice aspect of your rule that I didn't notice before is that
(assuming Kings cannot be uncaptured) it incorporates as a special case
the rule forbidding a King from moving through check when castling!

> Noam, could I ask you, what are your fields of interest at Harward

> University?

I teach mathematics at Harvard, and my research interests are mostly
in number theory. You can get a more complete picture from my
online bibliography: <math.harvard.edu/~elkies/math_pubs.html>

--Noam D. Elkies

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