[Retros] series SPG

[Richard Stanley]

Here is a variation of Noam Elkies' request for a dual-free SPG in
which every unit moves. Remove all Black units from the board. What is
the maximum number of White units that can move in a dual-free series
SPG? I can do 14 (if sound), but presumably that can be improved. The
same question can be asked without first removing the Black units.

Richard