Weekly Problems 2021-A

Problems 528-530

528

Jean-Marc Loustau
Ideal-Mate Review 1993, Prize

Solution

The diagram is solved by 1.Sxg3 Ke7 2.Ke4 Kd6 3.Bf3 Sxg3. Black’s first move vacates e4 and captures the knight guarding it, allowing the square to be accessed by the black king on the second move. After the white king approaches, the bishop goes to f3 and interferes with the rook, permitting a knight mate on g3, which was cleared by Black’s initial knight move. The solution of part (b), with a white pawn on d4 instead, is perfectly analogous: 1.Sxe2 Kf7 2.Kf4 Kg6 3.Rf3 Sxe2. Here Black first vacates f4 and captures its guarding knight, so that the black king can move to that square. The white king approaches via another path, and the rook interferes with the bishop by landing on f3, enabling a knight mate on e2 – the square cleared by Black’s initial capture. The two parts involve a Grimshaw on f3, a curious capture cycle of the four knights, and ideal mates.

Andy Sag: This tricky twin features delayed knight recapture after self-block preventing the king’s return to f3. The white king looks out of play but don't be fooled. Its placement on e8 ensures its unique path and also prevents a cook, 1.Re3 d3 2.Sg2 Sh5 3.Sf2+ making 3...Sg1 illegal!
Jacob Hoover: Since the white knights swap roles between getting captured and delivering mate, this is a Zilahi. Also, we see the black rook and bishop blocking each other, so there's another instance of role-swapping.
Ian Shanahan: Wonderful, perfectly matching strategy between the two solutions (including paradoxical captures of White’s already meagre force, as well as a black follow-my-leader in each). Note, too, the exchange-of-function between the two white knights, and that for both solutions White's mating square is the same as Black's capture square. Of course – given the name of the publishing journal! – both sequences end in an ideal mate.

529

Charles Promislo
Good Companions 1915, 1st Hon. Mention

Mate in 2

Solution

In this block position, set mates are arranged for all possible black moves: 1…Rh~ 2.Qf4, 1…Rg4 2.hxg4, 1…e5 2.Sg3, 1…exd5 2.Qxd5, 1…Sg~ 2.Rxf6, and 1…Sb~ 2.Sd4. Tries that attempt to maintain the block include 1.Qe3? exd5!, 1.Bg3? e5!, 1.d6? e5!, and 1.h7? Rxh7+! The key 1.Qc3! (waiting) leads to numerous changed mates that result from the queen observing different squares. Black’s h4-rook now generates four distinct variations instead of two: 1…Rh~ 2.Qf3, 1…Rf4 2.Sg3, 1…Rg4 2.hxg4, and 1…Rxh3 2.Qxh3, where the second line also shows a transferred mate (from the set 1…e5 2.Sg3). The e6-pawn provokes a single new mate, down from the two prepared: 1…exd5/e5 2.Qc8. One more change comes from the g8-knight – 1…Sg~ 2.Qxf6, while 1…Sb~ 2.Sd4 is as set. A classic mutate from a great exponent of the form.

Andy Sag: Complete block. The key sacrifices the queen, moves double guard from f4 to e5 and features no less than five changed mates!
George Meldrum: A nice array of changed mates. A breeze in comparison to last week’s problem which was impossible to solve.
Nigel Nettheim: The complete block is handled by changing most mates. The changed play with the h4-rook is a highlight (rather than the sacrificial key).
Andrew Buchanan: Beautiful! Why wouldn't a lovely problem like this get a prize?
Ian Shanahan: The American problemist Charles Promislo was renowned for his sophisticated and elegant mutates (this being one of his very best). As with many mutates – i.e. complete blocks with mate-changes between set- and actual-play – the key is pendular; this time I spotted it instantly! The construction is absolutely perfect. Pure art!

530

Martin Hoffman
Die Schwalbe 2013, 6th Hon. Mention

Mate in 5

Solution

The black rook, while uncapturable due to stalemate, is defending against mating threats by both the c5-rook along the a-file and the d8-knight on c7; thus 1.Se6? Rf8+! or 1.Ra5+? Rxa5 2.Se6 Ra7. No progress is made by 1.Rc4? Rf4! or 1.Rc3? Rf3!, and 1.Re5? simply fails to 1…Rxe5! Correct is 1.Rd5! which puts Black in zugzwang. Short mates follow the weaker defences, 1…Rxd5? 2.Se6 then 3.Sc7, and 1…Re5? 2.Se6 Rxe6 3.Ra5. After 1…Rg5, 2.Rd1 exploits the placing of the g2-pawn, which hinders 2…Rg1, and the only way to prevent 3.Ra1+ is 2…Ra5, permitting 3.Se6 Ra7 4.Ra1 Rxa1 5.Sc7. The thematic defence is actually 1…Rh5, which seems to handle 2.Rd1 with 2…Rh1. But the terrific 3.Rg1! traps the black rook into another zugzwang position, as after 3…Rxg1 4.Se6 the black rook is lodged behind g2-pawn and cannot stop 5.Sc7.

Andy Sag: The black rook obviously can’t be captured so White’s mission is to force it to an obstructed position from where it cannot check after Se6 threatening Sc7 mate. The c2-pawn prevents a dual after 1…Rh5 2.Rd2, etc.
Mark Salanowski: Fantastic interplay between the two rooks. Deceptively hard problem to solve – moving the rook to the g1-square is hard to see as it looks so useless there.
George Meldrum: A true cat and mouse game. Amazing.
Michael McDowell: The Hoffmann is a lovely little problem. Ideal for solving from the diagram, very easy to set up from memory, and just the sort of thing with which to challenge a player.