[Retros] [tros] Happy New Year

[Noam Elkies]

I wrote:

>> That's a wonderful discovery.  I have nothing comparable to offer, but to
>> avoid interrupting a 10+ year tradition -- and hint at what will be possible
>> next year -- I offer the following capture-free SPG enumeration where all
>> the threads contribute to the final pure mate:

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

> Nice mate, mate!

Thanks!

> Thanks for your kind words. They say a conjurer should never repeat a trick,
> but I was wondering today if I could make a pretty picture from 1959, the
> year of my birth, which is not promising factor-wise. I stumbled across
> this:

> www.janko.at/Retros/d.php?ff=rnbqkbn1/pp1Rppp1/4P3/7p/P7/3p4/1PPPr1PP/1NBQKBNR
> How many ways to reach this diagram at the end of Black's 8th move?

> This looks like another "rook-and-pawn opening" but the logic and arithmetic
> are rather different from 2015.

Neat -- it's basically the same logic that I used (minus Black's
count-rectifying first move), but unified by check assymetry as in
your 2015 puzzle rather than the final mate of mine.

> Roll on (2^6-1)*2^5 (although we've got a lot of (2^6+1)*(2^5-1) to get
> through first)!

Indeed.
--NDE