[Retros] Happy New Year

Noam Elkies elkies at math.harvard.edu
Wed Sep 16 17:27:16 EDT 2015

"Andrew Buchanan" <andrew at anselan.com> writes:

> Happy New Year, Noam,

Thank you.

> Your harmonious identity 5775 = (78-1)*(78-3) encouraged me to think
> that a symmetric diagram might be possible:

> http://www.janko.at/Retros/d.php?ff=2k3rr/pppn1ppp/2qpp3/1b2b2n/N2B2B1/3PPQ2/PPP1NPPP/RR3K2
> PG in 13.0 C+ Popeye 4.73 in 4.59 minutes.

Very nice!  Naturally that's the kind of setting I was aiming for,
but -- at least in the Zeitnot of the impending New Year -- was only
able to approximate it.  The f1-b5 and g4-c8 diagonals suggest that
the asymmetry might be implemented by check avoidance (or avoidance of
castling through check), but in fact W and B remain independent, and
the K/Q asymmetry is exploited in another way.

Meanwhile, Popeye 3.41 finally confirmed my (78-1)*(78-3) problem
in just over three days -- and meanwhile Mario Richter reports that
his "rawbats" C+'d it in three seconds!  Or 18 seconds without the
constraints/hints that each b-pawn must not move until its a-Rook
has moved twice.  Thank you!


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