[Retros] # Pb2->B (6.5)

[Noam Elkies]

CF> Hopefully this can be improved to 6.5!

I didn't find a way to get to 6.5 with Bg6#, so here's Bb6# instead:
1 b4 e6 2 b5 Ke7 3 b6 Qe8 4 bc b5 5 c:b8=B Kd8 6 B:a7 Be7 7 Bb6#
(C+, .1 sec.).

NDE