This week's column looks at one of the most famous themes in problem chess. The essence of the idea is a particular type of interfernce, where two pieces on the same side get in each other's way. Our first example, one of the finest two-movers of all time, shows the idea beautifully:
Lev Loshinski
Commendation, Tijdschrift v d NSB 1930
Mate in two
The first thing to note about the position is that Black is in what an OTB player would call zugzwang, since if it were his move, there is a mate set against every possible black move (check for yourself!). This makes the problem what is called a complete block. It follows that White needs a waiting move. This is 1.Bb3. Now let us see some of the mating variations. If 1...Bb7 White has 2.Re7# because the Bb7 interferes with the BR's action along the 7th rank. Likewise, after 1...Rb7 there is 2.Rc6#, as now, the BR on b7 interferes with the bishop's diagonal from a8.
This mutual interference of the black rook and black bishop is the key theme of the problem, and is known as the Grimshaw theme, after the 19th century English composer Walter Grimshaw, who first showed it. But, to use the catchphrase of a particularly dreadful English comedian of bygone years, "There's more". If we look at the top-right-hand corner of the board, we see another BR/BB combination, and sure enough, we have another Grimshaw here: if 1...Bg7 2.Qxf7#; whilst if 1...Rg7 2.Qe5#; once again, the BR and BB interfere with each other's actions. There is even a third Grimshaw concealed in the position, although this time not a pure R+B Grimshaw, but a Pawn Grimshaw: if 1...f6 2.Qe4# (because the pawn on f6 stops the defence Be5), whilst if 1...Bf6 2.Qg4# since the Bf6 stops the defence 2...f5.
So that is the idea – rook and bishop interfere with each other. That one showed two pure Grimshaws and a Pawn Grimshaw, but Loshinski was one of the greatest composers ever, and was clearly not satisfied. The same year, he managed to show three pure Grimshaws:
Lev Loshinski
1st HM, L'Italia Scacchistica, 1930
Mate in two
The key is 1.Rb1. By defending the QN again, White threatens mate by 2.d4. Black has three defensive ideas. The first is to cut the b1–b4 line, so that 2.d4 would allow the BK to capture on b4. This provides our first Grimshaw: 1...Rb2 2.Qxc3# and 1...Bb2 2.Qf2#; The second defensive strategy is to cut the guard along the fourth rank, so that 2.d4 can be met by 2...Kxd4. This gives us Grimshaw number two: 1...Rg4 2.Ne6# and 1...Bg4 2.Bg1#; Finally, Black can cut the g8-a2 diagonal, so that after 2.d4 his king would have a flight on c4, and this results in our third Grimshaw: 1...Re6 2.Nd7# and 1...Be6 2.Bd6#! Like the previous one, this remarkable problem did not even make the main prize award, getting only 1st Honourable Mention!
Of course, it is also possible for the interference to result from a sacrifice on the intersection square. This closely-related theme is known as a Novotny, after the Czech composer of that name. In our next example, we have a double Novotny:
Helmut Pruscha
1st Prze, Deutsche Schachzeitung, 1959
Mate in three
The key is 1.Rh7, which threatens 2.Qe6+! with a standard R/B interference pattern: 2...Bxe6 3.Ne8# and 2...Rxe6 3.Nf5#. Black can defend by playing his bishop over the key square e6, to either h3 or g4, but then we get another Novotny interfence on e6, this time by the white knight: 1...Bh3 2.Ne6! followed by 2...Bxe6 3.Qe7# or 2...Rxe6 3.Qd7#.
Thus far, it has been White who has had all the fun, but of course, Black can also exploit these ideas.
Isaac Birbrager
HM, Molodikh Avtorov, 1948
Mate in two
This is an example of a problem, for a full appreciation of which one needs to see not only the solution, but also the lines which fail. White has two tries, i.e. moves which would work, but for a single black defence. The first try is 1.Be4? threatening 2.Rf5 mate. This can be met by 1...Rd2! since now White does not have 2.Re1 mate. Likewise, the try 1.Re4? (threat 2.Rf4 mate) fails to 1...Bd2! since now White does not have 2.Bxd3 mate. In other words, the tries are defeated by a white Grimshaw on e4. But after the correct key 1.Bh7! (again threatening 2.Rf5 mate), Black finds himself hoist by his own petard – the defences now fail because of a black Grimshaw on d2: 1...Rd2 2.Re1#; 1...Bd2 2.Bxd3#. Lovely stuff, I hope you'll agree?
Next time, we will look at some more exploitations of the Grimshaw/Novotny theme, including its use in selfmates and helpmates.
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