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

[Richard Stanley]

> 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.


By a midboard mate, do you mean a mate where the king is in the middle
of the board (with no additional conditions)? If so, here is one in 
4.0 (not an SPG):

1.d4 e6 2.Kd2 Qg5+ 3.Kd3 Qg3+ 4.Ke4 f5#

It can also be done from the other side, but still not quite an SPG:

1.f4 e6 2.Kf2 Qf6 3.Kf3 (or Ke3) Qc3+ 4.Ke4 d5#

If c4 is considered "midboard" then there's an SPG in 4.0:

1.d4 c6 2.Kd2 Qa5+ 3.Kd3 Qa3+ 4.Kc4 b5#

What is a mirror mate?

Richard