[Retros] En Passant Chess (Noam Elkies)

[Noam Elkies]

> 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>

Sincerely,
--Noam D. Elkies