Dark Doings problems – Part 2

Dark Doings problems involve an extreme form of material imbalance: White has at most one unit besides the king, while all sixteen black pieces are present. As mentioned in Part 1 of this series, Ottó Bláthy pioneered this picturesque scheme in the 1920s, and even then, he implemented it not only in directmates but also in less common types, such as selfmates (though some of them proved to be unsound by modern standards). The Dark Doings idea has since been rendered in many other genres, including fairy types like series-movers, and even proof games. The quirky Weekly Problem No.700 demonstrates it – along with the “homebase” effect – in a helpstalemate. For this instalment, however, I shall focus on helpmates, which seem particularly conducive to producing high-quality examples.

In the first diagram, the black king has numerous flights that aren’t easily blocked, and a queen mate is achievable in time only with the assistance of the white king. For part (a), White aims for a queen mate on d4, which requires only one self-block on c2, but it also necessitates a guard of the queen by the king on e5. Black executes two self-interferences to give the king access to that square. 1.Bf5 Qg1 2.Rd6 Kxe5 3.c2 Qd4. For part (b), where the e2-queen begins on e3, a similar mating arrangement is possible with the black king on d4 and the white queen on d5. To support the queen, the white king moves to e6, which likewise must be unguarded by Black. 1.Bd6 Qa8 2.Rf5+ Kxe6 3.Kd4 Qxd5. Two attractive pairs of Grimshaw interferences come about with an unusual motivation, to legalise the white king’s moves. The two mating configurations are chameleon echoes, where the participating pieces change their square colours.

The single white pawn on the seventh rank coupled with the stipulated four solutions points to a likely Allumwandlung, and indeed four different promotions occur. What’s extraordinary here is how much extra contents the problem incorporates. 1.Kc4 e8=Q 2.Qd5 Qd7! 3.c5 Qxa4. The new queen plays to d7 as the only possible tempo move for White (avoiding, for instance, an earlier 1…Kc7? which would have self-pinned the pawn). 1.c5 e8=R 2.Kc6 Re7! 3.d5 Rxe6. The rook underpromotion ensures that the black king can reach c6, and the promotee similarly plays a waiting move on its way to e6. 1.Bf7 e8=B 2.Ke6 Bxc6! 3.Qd5 Bd7. Here the king isn’t barred from e6, thanks to the bishop underpromotion, and the promotee captures on c6 solely to waste a move. 1.Ke4 e8=S 2.Bd5 Kc8! 3.Rd4 Sxd6. Since the knight is unable to lose a tempo, the white king takes over that task. In addition to the AUW and four-fold tempo play, this helpmate features star-flights by the black king and four model mates. If only there were four different self-blocks on d5 – there are only three because Qd5 is repeated. Regardless, this stunning piece of work deservedly earned the maximum 12-points in the FIDE Album.

For each type of white piece on f6, we have to find a suitable mating square for the black king and appropriate self-blocking units that won’t disturb the mate. In (a), the king heads for f4 to set up a rook mate on the f-file, meaning the f5-pawn needs to be removed and the e3-square blocked. 1.Kd4 Rxf5 2.Ke3 Rg5 3.Kf4 Rg6 4.Qe3 Rf6. In (b), the king is mated on d4 by the bishop along the long diagonal, so White captures two hampering pieces while Black blocks three flights. 1.Rd3 Bxe5 2.Se3 Bd6+ 3.Kd4 Bxe7 4.Qc5 Bf6. Lastly in (c), the king goes to e8 to be mated by the knight on f6; hence White clears the e8-square and Black self-blocks d8. 1.Kd6 Sxe8+ 2.Kd7 Sd6 3.Qd8 Sxe4 4.Ke8 Sf6. All three white officers harmoniously make a four-move rundlauf or round-trip, delivering mate from the same initial square.

Our last selection is not difficult to solve, despite its length. The white king is incarcerated, which effectively traps the pair of black knights as well, since moving either would result in a battery mate. That leaves the g2-pawn as the only unit capable of freeing the white pawn from the h-file, though again Black must be careful to avoid giving mate, e.g. not 1.g1=B? and 2.Be3. Only 1.g1=S works, then the white pawn starts by making a hesitating move. 1…h3! 2.Sf3 h4 3.Sg5 hxg5 4.h4 g6 5.h3 g7 6.h2. Now a white queen promotion fails because potential mating squares for the piece, such as d2 and c2, cannot be unguarded by Black. So 6…g8=S to aim for a knight mate on e4, an idea that requires no further assistance from Black. However, Black cannot pass and therefore must pick a promotion that’s non-disruptive: not 7.h1=S? Sf6 when either 8.Sg3/Sf2 would prevent the mate. The correct choice 7.h1=B surprisingly controls the mating square at once, but there’s time to sacrifice the new piece, 7…Sf6 8.Be4 Sxe4. We see three precise underpromotions plus tempo play by both sides, along with an Excelsior performed by the white pawn.

Dark Doings problems – Part 1

24 Apr. 2024