[Retros] [tros] Happy New Year

[Noam Elkies]

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

> www.janko.at/Retros/d.php?ff=1nbqkbnr/1prpPppp/8/p7/7P/8/PPPpPRP1/RNBQKBN1
> How many ways to reach this diagram at the end of Black's 8th move?

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:

White  Rf4 Sb1 Bf6 Qd1 Ke1 Be2 Sg1 Rh1 Pa5 Pb5 Pc2 Pd2 Pe3 Pf2 Pg2 Ph2
Black  Ra8 Sd7 Bc8 Qd5 Kc6 Bc5 Sg8 Rh8 Pa7 Pb7 Pc7 Pd6 Pe6 Pf7 Pg5 Ph7
http://www.janko.at/Retros/d.php?ff=r1b3nr/pppn1p1p/2kppB2/PPbq2p2/5R2/4P3/2PPBPPP/1N1QK1NR

C+ Popeye in <1 second.

Happy Binary Palindrome Year,
--NDE