[Retros] Double-pin mate

Nicolas.Dupont at math.univ-lille1.fr Nicolas.Dupont at math.univ-lille1.fr
Sun Nov 12 02:23:24 EST 2006

Andrey asked :

> How many pins can be effective in the mate position of an SPG (regardless

> of the mating piece)? Three? Four? Or even more?

It's not so complicated to get four...

1.Pa2-a4 Ph7-h5 2.Pa4-a5 Ph5-h4 3.Pa5-a6 Ph4-h3
4.Pa6xb7 Ph3xg2 5.Ph2-h4 Pa7-a5 6.Ph4-h5 Pa5-a4
7.Ph5-h6 Pa4-a3 8.Ph6-h7 Pa3-a2 9.Th1-h6 Pa2xb1=T
10.Cg1-h3 Pg2-g1=T 11.Ta1-a3 Tg1-g5 12.Ta3-g3 Ta8-a1
13.Ph7xg8=T Cb8-a6 14.Pb7-b8=T Fc8-b7 15.Tb8-c8 Fb7-h1
16.Pe2-e4 Pc7-c5 17.Ff1-b5 Pc5-c4 18.Dd1-h5 Tg5-c5
19.Pf2-f3 Pe7-e5 20.Th6-e6

Obtaining five effective pins needs of course a completely different kind
of strategy (the thematic king must probably stand around the center of
the board). It should probably exists, although I have strictly no idea of
how getting it.

Other researches can be made on that 4-pins task. For examples :
- fewer moves
- no visible promoted piece
- AUW-like

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