The BDS Website

BDS & Stephen Emmerson

The Problemist Supplement, 2001

#2
TRITONs b6, f1
SCYLLAs f2

1.TRxb3-b2! (2.SKh1#)

1...Qxe4     2.Ra3#
1...Rxe4     2.Se5#
1...Rxg4     2.Sg5#
1...Sxg4     2.Rf6#
1...Qb8      2.e5#

In the diagram position the wRe2 is guarded by the SKf2, so if that Scylla were to move away, the bK could escape to e2. To threaten 2.SKh1#, White must first play to guard e2 after the Scylla moves. This explains the key. Black can defend by taking on e4 or g4 and if the Scylla then moves, Black can move to f4 (after the first three defences) or interpose on f2 (after the fourth defence). All these moves, however, are self-pins, pinned by the Scylla. After them White can mate taking advantage of the pin, thus making these Nietvelt Defences. The fifth defence, not a self-pin, prepares to play to f4 to annull the threatened check, but then White open the SK+P battery and mate by 2.e5#. It’s a pity that we couldn't work in 2.g5#