[Retros] pure Q/B ##'s, and a mirror

[Noam Elkies]

Don't think we have any Q/B double checkmates yet;
here's a pair showing an amusing pure mate configuration:

1 g3 e5 2 Bh3 Qg5 3 B:d7+ Ke7 4 h3 Q:d2+ 5 B:d2 Kd6 6 Bb4##

1 d3 Nc6 2 Bg5 Nd4 3 B:e7 N:e2 4 B:e2 d5 5 Kf1 Kd7 6 Qe1 Ke6 7 Bg4##

(both C+, in 110 and 210 msec. respectively)

While we're at it, is there an SPG ending in a midboard mirror mate
shorter than the following?

1 e4 c5 2 Ke2 Qb6 3 Kd3 Q:b2 4 Kc4 Qb3+ 5 K:c5 e5# (C+ 110 msec.)

It's hard enough to find any shorter game (not necessarily SPG)
ending in a midboard mate; the best I can find is 4.5 moves long.

NDE