[Retros] series SPG

[Nicolas DUPONT]

Dear retro friends;

In Richard's very interesting list of series mates, the first unknown
feature is :


>Ng1: ?


I propose the following (one-sided) game :

3) Ngb5 4) d4 5) Bg5 6) f4 9) Kh4 10) g3 11) Bg2 15) Re6 16) e3 17) Qf3 18)
Qxb7
19) Qxc8 20) Nxc7 #

Of course, I'm unable to prove that 20 is  the shortest number to do that
job. I'm even unable to be sure that this game is sound (one-way ticket).
Indeed, "popeye" says nothing after 2 days of analysis, although it seems
that everything  is OK :

The last position of the Ng1 (before mating) cannot be e6 because of the
rook, cannot be d5 because the queen goes through that point, and cannot be
reached to b5 via e2 because e3 comes too late. Moreover, b7 and Bc7 must
have been captured by the queen, because there are only 20 moves.

So, what do you think about that ? I forgot something ?

Sincerely;

Nicolas Dupont.