[Retros] Happy New Year

Noam Elkies elkies at math.harvard.edu
Sun Sep 13 16:25:37 EDT 2015

Not 3+ months early, but a different calendar:

White  Ra1 Sb1 Be3 Qe1 Kf1 Bg2 Sh1 Rd4 Pa2 Pb2 Pc2 Pd3 Pe4 Pf2 Pg3 Ph5
Black  Re5 Sa8 Bb7 Qc8 Kd8 Bd6 Sg8 Rh8 Pa4 Pb6 Pc7 Pd5 Pe6 Pf7 Pg7 Ph7

C+ Popeye 3.41 in ~1 second

The departing year 5775 on the Jewish calendar is not only palindromic but
blessed with numerous factors and thus many routes to an enumerative SPG.
I think this works:

White  Ra1 Sa4 Bc1 Qd1 Kg5 Bf1 Sh4 Rh1 Pa2 Pb2 Pc3 Pd2 Pe2 Pf3 Pg2 Ph2
Black  Rb8 Sd7 Bh3 Qd8 Ke8 Bh8 Sg8 Rc6 Pa7 Pb7 Pc7 Pd6 Pe5 Pf7 Pg6 Ph5

C+ Popeye 3.41 in ~1 second

A closer analogue to the 5776-solution problem would be

White  Rb4 Sc3 Ba3 Qf3 Kf2 Bf1 Sg1 Rh1 Pa4 Pb3 Pc2 Pd2 Pe2 Pf4 Pg2 Ph2
Black  Rb5 Sb8 Ba6 Qh6 Kf7 Bf8 Sf6 Rh8 Pa5 Pb6 Pc7 Pd7 Pe7 Pf5 Pg7 Ph7

but Popeye has been churning at it for 25+ hours now and has turned up
only 924 solutions, so it might not finish before the relevant year
draws to a close (as it already has in Israel and Europe and points
further East); I suspect it's working so hard because it thinks
that the Queens and Rb4/b5 have each wasted a move...  Perhaps a more
recent Popeye, or a different program, can check it in reasonable time.

Shanah Tovah,

More information about the Retros mailing list