Weekly Problems 2020-A

Problems 476-487

476

Molham Hassan & Geoff Foster

Australasian Chess 2010

Mate in 2

Solution

A good key 1.Qh4! grants a flight on e5 and sets up a battery on the fourth rank, which threatens to open with 2.Sg6. The black knight has three defences that allow the h8-bishop to cover the e5-flight, and they produce three more battery mates: 1…Sh5 2.Sxh5, 1…Se6 2.Sxe6, and 1…Sxf5 2.Sd5 – the latter a pin-mate where White regains control of e3 and d4. A switchback occurs if Black takes the offered flight: 1…Kxe5 2.Qe7. Lastly, 1…d2 is answered by 2.Re2. The three battery variations show a duel between the two knights.

Andy Sag: A flight-giving key with switchback. I like the two variations that self-pin the black knight.

Jacob Hoover: The black knight has three defenses, and each one forces a different knight discovery.

Ian Shanahan: The two star variations are 1…Kxe5 2.Qe7 (the black king takes the flight proffered by the key, met by a switchback and pin-mate), and 1…Sxf5 2.Sd5 (the Schiffmann theme). A fine problem in traditional style.

477

Alfred Figdor

The Australasian Chess Review 1943, 1st Prize

Mate in 3

Solution

The white knight on f2 has four moves that threaten mate, but three are defeated by its capture while 1.Sg4? is neutralised by 1…Rxb6! The key 1.Ba4!, threatening 2.Be8 and 3.Bxf7, induces Black to disable the four potential defences against the knight moves. 1…c6/Rxa4 2.Sg4 and 3.Sxf6. 1…Bb1 2.Sh1 and 3.Sxg3. 1…c3 2.Sd3 and 3.Sf4. 1…d4 2.Se4 and 3.Sxf6/Sxg3. Consistent white knight play and in three variations Black deftly handles the threat by activating the a2-bishop.

Jacob Hoover: White unravels this problem with 1.Ba4!, sacrificing the bishop to the a6-rook. In each line a black unit either is decoyed away from guarding a vital square or blocks a guard of a vital square.

Andy Sag: The four set plays by the f2-knight make a nice theme.

478

Efren Petite

Australian Chess Problem Magazine 1997

Mate in 2

Solution

A white bishop move along the long diagonal will open the e-file and threaten 2.Qe4, a mate that requires the queen to observe both e6 and c4. Black can defend by placing a knight on e5 or d4, moves that also pin a white rook and thereby prevent it from mating on an unguarded square. In two thematic tries the bishop is placed to interfere with one of these pin-lines: 1.Bg7? Se5 2.Rxd6 (1…Qxe3 2.Sxe3, 1…Sd2 2.Sc3) but 1…Sd4! refutes, and 1.Bb2? Sd4 2.Rxc5 (1…Qxe3 2.Sxe3, 1…Sd2 2.Sc3/Rxc5) but 1…Se5! refutes. The key 1.Ka6! creates a new threat of 2.a8(Q), against which the knight defences also work. But thanks to the anticipatory unpinning effect of the king move, these defences no longer counter the rook mates: 1…Sxe5 2.Rxd6 and 1…Sd4 2.Rxc5. The key-move controls b5 so that if Black takes the flight, the threat is still playable: 1…Kc6 2.a8(Q); hence not 1.Kc8? Kc6! Another good try is 1.Re7? (2.Qe4) Sd4 2.Qxd4 (changed mate), 1…Bxe7 2.Sb6, but 1…Qxe3!

Andy Sag: The key breaks two half-pins. It also gives a flight which is illusory as it fails to defend the threat. The bishop tries involve the same defences which use rook pins to work.

Andrew Buchanan: Found this very hard to solve, because of so many tries. I was particularly enraptured by 1.Bb2? and 1.Bg7?

George Meldrum: The tries 1.Bb2 and 1.Bg7 look tempting yet fail. Next attention is drawn to the innocuous pawn on a7 but immediate promotion fails. The flight-giving key looks an unlikely move. So many good problems have an obvious key – this is not one of them.

Ian Shanahan: The rook-mates thwarted in the tries occur as mates after their black refutations in the post-key play! A classic reversal-pattern. A heavy, but satisfying problem.

479

H. Cox

The Australian Problemist 1963

Mate in 2

Solution

White mating replies are prepared against all possible black moves in the diagram: 1…Sc~ 2.Re6, 1…Se~ 2.Sdc6 (dual 1…Sd5 2.Sdc6/Sbc6), and 1…e3 2.Sf3. But White has no waiting move capable of preserving all of the set play, e.g. 1.Kxg3? Sxf5+!, 1.Qg5? h4! The unexpected key 1.Sb5! (waiting) abandons not only both set knight mates but also the rook mate on e6 (by unguarding f5). Three new mates arise, however, due to a multitude of effects brought about by the key: 1…Sc~ 2.Rxe4, 1…Se~ 2.Rxc5, 1…Sd5 (correction move) 2.Sc6, and 1…e3 2.Qd4. The key-piece has to choose b5 to place an extra guard on d6, otherwise 1…Se6! would be too strong. The composer Cox had a knack for creating mutates that are difficult to solve.

Andy Sag: A waiter with four variations including three changed mates. Can convert to a Meredith by shifting the white king to e1, removing the g-pawn and moving everything else down one square.

Jacob Hoover: A rather nice block-mutate.

George Meldrum: Heaps of changed mates; dual eliminated. Nice.

Ian Shanahan: A lovely all-change mutate with a black correction in the post-key play. Very pretty and elegant!

480

Ian Shanahan

Springaren 2012

Solution

The attractive diagram position exemplifies one-row asymmetry, where a symmetrical set-up nevertheless yields a single solution, by utilising the board edge in some way. 1…Kf5 2.Sf3 g4 3.Se5 g5 4.Sf7 g6 5.Kh6 g7 6.Sh8 gxh8(Q). Good black and white interplay ensures that the knight route to h8 is unique, and there’s an ideal-mate finish.

Andy Sag: A pawn mate is possible using the knight as a self-block but that takes seven white moves, so promotion to a queen on h8 is clearly indicated. The black king must wait for the pawn to arrive at g6 before moving and the knight must go via e5 to keep the g-file clear thus ensuring unique play.

Andrew Buchanan: Crafted with Ian’s usual elegance and attention to detail. A pleasure to see why the black knight could not land on any other square on the h-file.

481

Alex Boudantzev

Friends of Chess 1972, 3rd Prize

Mate in 2

Solution

The B + R/R half-battery on the long diagonal and the Q + S battery on the first rank are both controlled by the black queen. If either rook moves off the diagonal, White will threaten Rf4 by the other rook, shutting off the queen. Random moves of the two rooks are mostly defeated by 1…Bf5!, which not only stops Rff4 directly but also cuts off the g6-bishop to create a flight on b1. The thematic try 1.Rb6? forestalls 1…Bf5 by guarding b1 and it leads to 1…Qd6+ 2.Rdxd6, 1…Qh3 2.Rd3, and 1…Qxg2 2.Rd2 (plus various Q + S battery variations similar to the post-key play), but 1…Qg1! refutes. The key 1.Rd7! (threat: 2.Rff4) prevents the bishop defence and produces 1…Qd6+ 2.Rfxd6, 1…Qh3 2.Rf3, 1…Qxg2 2.Rf2 (three changed mates compared with the virtual play) and 1…Qg1 2.Rf2. Further, 1…Qg3 2.Sf2, 1…Qe5 2.Se3, 1…Qc7 2.Sdc3, and 1…Qb8 2.Sdb2 show more precise battery shut-offs. Including the virtual play, we see ten distinct battery variations (counting 1…Qxg2/Qg1 2.Rf2 as one), all instigated by the black queen.

Andy Sag: The diagonal half-battery gives a strong clue and the first rook must block the c8-h3 diagonal but the correct rook must be chosen because 1.Re6? fails to 1…Qg1/Qh3! All eight mates are battery mates including the threat.

Andrew Buchanan: Black is threatening 1…Qd6+ [an unprovided check], and that forces the key to be by one rook.

George Meldrum: But which rook move? That that stops Black playing 1…Bf5 and provides a mate after Black playing 1…Qg1. Eight mates in a cornered king problem; what’s not to like!

Jacob Hoover: This is an absolute gem of a problem.

Ian Shanahan: Classic half-battery involving numerous tries, with the black queen losing focal control of each of the two battery lines in turn thence being shut off by one of the batteries’ firing pieces for her troubles (the Mackenzie theme). A ‘trying’ problem, difficult to solve, but flaunting rich play and numerous changes between try and key.

482

Laimons Mangalis

Deutsche Schachzeitung 1980

Solution

If it’s Black’s turn in the diagram, every legal move gives mate immediately. White cannot avoid disturbing this block position, however; the white queen in particular has numerous tries that are subtly defeated. 1.Qa5/Qb4/Qc5/Qc4? (controls e1 or c1) Sa3+! (not 1…Sc3, a shut-off mate), 1.Qa4? (controls d1) Sc3+! 2.Qd1+ Sxd1 (not 1…Sa3+? 2.Qd1+ Rxd1), and 1.Qd7? (controls h3) Qxh3+! 2.Qxh3 Bg2+ (and ironically White is forced to mate with 3.Qxg2). Most rook moves along the h-file are refuted by the piece’s capture by the black queen, but 1.Rh7! (with a technical threat of 2.Rh3) works by drawing the queen to the right square for 1…Qxh7 2.Qd3+ Qxd3. Other vertical defences by the queen are answered by a grab – 1…Qh6 2.Rxh6, 1…Qh5 2.Rxh5, 1…Qh4 2.Rxh4 (and 1…Qh3 2.Rxh3), all leaving Black in zugzwang and compelled to mate with 2…S~/Bg2/g2. Since the set play totally consists of immediate mates by Black and the key has to extend the play to two moves, this selfmate is a pseudo one-mover (not possible in a directmate).

Andy Sag: All black moves are mates in the set position. The tricky key forces the black queen to move but stay on the h-file. Many tries, notably 1.Qd7? Qxh3+! and 1.Rxh2? gxh2! and the black king is free to move to g3.

Jacob Hoover: The key must give Black at least one non-mating move and 1.Rh7! does this quite nicely.

George Meldrum: A nice hair-pulling problem with lots of ‘almost works’ solutions. The line that ends with the black queen moving to d3 to mate the white king is absolutely brilliant.

Andrew Buchanan: Very clever. I like the geometry of this very much, and the solution is well hidden.

Ian Shanahan: A cleverly constructed problem! Any move by the white queen fails.

Bob Meadley: That's a lovely selfmate by Mangalis.

483

Alberto Mari

The Brisbane Courier 1922, 3rd Prize

Mate in 2

Solution

The key 1.Qe6! threatens a pin-mate, 2.Qc8, against which Black can defend by unpinning the g4-queen. The two black pieces capable of doing this are themselves half-pinned by the white bishop, so when either moves, the other is immobilised and this leads to another pin-mate: 1…Be4 2.Rd4 and 1…Sf4 2.Qe4. Remarkably, both variations involve another strategic effect: the defender interferes with the black queen’s control of the mating square on the fourth rank. Two other defences unpin the d5-knight, which gives a pair of battery mates, nicely differentiated: 1…Rg6 2.Sf6 and 1…Bf5 2.Se3. The by-play makes additional use of the thematic pieces: 1…Sd4 2.Bxd3 and 1…Rxd5+ 2.Qxd5.

Andy Sag: Pin-mate theme with many tries: 1.Qg8? Sf4!, 1.Qe8? Rxd5+!, 1.Qf3? Sc1!

Ian Shanahan: Classic Good-Companions-style problem from the Italian expert. In the thematic variations, each half-pinned piece unpins by interference the black queen; pin-mates result. Rich strategy indeed!

484

Alexander Goldstein

Arbejder-Skak 1954, 8th Hon. Mention

Mate in 2

Solution

The waiting key 1.Kf4! completes the block. A random move of the d8-rook unguards d7: 1…R~ 2.Qd7, while its correction move blocks a flight: 1…Rd6 2.Qe4. Similarly, the g8-bishop unguards f7 with a random move: 1…B~ 2.Bf7, and self-blocks with a correction: 1…Be6 2.Qc5. The a5-knight provides a third pair of thematic defences: 1…Sa~ 2.Bc6 and 1…Sc4 2.Rd3, involving the same sorts of errors as the other pairs. Lastly, 1…Sg~ enables 2.Qe5. A textbook example of correction play, attractively set.

Andy Sag: An easy to solve pawnless, Meredith, dual-free waiter with three self-block and four unguard variations.

George Meldrum: Three of Black’s pieces have moves for which White has no reply. The key move covers e4 and e5 enabling the zugzwang setup.

Andrew Buchanan: Mirror mates abound in this aristocratic position. For three of the black pieces, there is a generic move, plus a special one which blocks a square adjacent to the black king and allows a different mate. The key is a bit aggressive, but I can't see any interesting alternative diagram.

Jacob Hoover: A nice black-correction problem, and in Meredith and aristocrat to boot.

Ian Shanahan: The waiting key leads to secondary corrections by three of the black pieces in an economical setting. A beautiful, subtle problem – as one would expect of its author.

Michael McDowell indicates that this problem shows correction play only once, not three times! He writes: “Only the knight shows correction play. 1…Sc4 commits the random error of unguarding c6, corrects by closing the line c3-c6 and commits the second error of blocking c4. Neither 1…Rd6 or 1…Be6 commit their random error of unguarding d7 or f7. They simply avoid making it, so they don't correct anything.”

485

Denis Saunders

The Problemist 1994

Mate in 3

Solution

The key 1.Qb4! pins the f4-pawn and threatens a short mate, 2.g3. In the thematic variations, Black employs the c8-rook and a6-bishop to interpose on the fourth rank and unpin the pawn, but these defences result in a mutual interference between the two pieces. 1…Rc4 2.0-0 – vacates e1 to threaten 3.Be1 – 2…Rxc3/f3 3.g3 or 2…Rg6 3.Sxg6. 1…Bc4 2.0-0-0 – again threatens 3.Be1 – 2…B~/f3 3.g3 or 2…Rg6 3.Sxg6. Thus a black Grimshaw on c4 sets off white castling on both sides – very harmonious. There’s good by-play in which Black also defends by unpinning the f4-pawn: 1…Sd4 2.Qe7+ Rf6 3.Sg6 or 2…g5 3.Qxg5; 1…e4 2.Qxe4 (threat: 3.g3) Rg6 3.Sxg6.

Andy Sag: King and rooks in original positions make second-move castling an obvious suspect. Denis was well known for using castling in his problems. The threat is a short pin-mate with four pin breaker defences. The pin-mate after 1…Sd4 2.Qe7+ Rf6 is a nice touch.

Dennis Hale: The point of the problem is to activate a Grimshaw based on c4 with the two unpinning defences, 1…Bc4 and 1…Rc4. It is pleasing how each of the two self-interferences is met by 0-0-0 or o-o, but not both.

Jacob Hoover: One try 1.Qa4? has the same idea as the key but dies to 1…Sd4! since from a4 the queen has no access to the e7-h4 line.

George Meldrum: Even though it was obvious that castling was to be a feature the need was obscure. Lovely spread of pieces and ingenious execution of interference play.

486

Shergili Sukhitashvili

Chess in Australia 1981

Mate in 2

Solution

Two important set variations are 1…Qxd4 2.Sxf4 and 1…Be6 2.Qc6. The first of two thematic tries, 1.Bc5?, threatens one of these set mates, 2.Sxf4, and the other set mate recurs but against a new defence: 1…dxc5 2.Qc6 (1…R~ 2.Bxe4, 1…Bh6 2.Qxg8). This try is refuted by 1…Qxd4! (a paradox as this defence allows 2.Sxf4 in the set play but defeats it here). The second thematic try 1.Rxf6? threatens the other set mate, 2.Qc6, and now another new defence induces the first set mate: 1…exd4 2.Sxf4 (1…Rxf6 2.Bxe4). But there’s no answer to 1…Sb4! Besides rendering a double mate transference relative to the set play, the two tries show the pseudo le Grand pattern: a reciprocal change of threat and variation mate (the latter in response to different defences). The key 1.Sxc4! grants a flight on c4 and threatens 2.Sb6. Now the two thematic mates appear again but they work against a third pair of defences: 1…bxc4 2.Sxf4 and 1…Kxc4 2.Qc6. Also, 1…Be7 2.Qxg8. An amazing 3x2 mate transference scheme, blended with the pseudo le Grand.

Andy Sag: The key allows a flight-capture. Curiously, the threat becomes a pin-mate after 1…Qxd4 and duals with 2.Rxd4, another pin-mate, and one of the variations is also a pin-mate.

Jacob Hoover: In this problem we have mate transference across four phases of play. Each try transfers one of the thematic mates to the threat while transferring the other to another defense. Also, the key transfers both mates to completely different defenses altogether (that both of these defenses are captures at c4 was a very nice touch!).

Ian Shanahan: It was difficult to distinguish between the symmetrical try and the key. A heavy but satisfying problem.

487

Zacharias Fjellström

The Sun-Herald 1961, Commendation

Mate in 2

Solution

In the set play, the white queen gives two different mates when unpinned by the black knights: 1…Sd3 2.Qd4 (not 2.Qxb4?) and 1…Sf5 2.Qxb4 (not 2.Qd4?). Another set variation is 1…e5 2.Bd6. The key 1.Sa5! places an extra guard on c4 and threatens 2.d4. The knight defences of the set play are effective against the threat, but White must exploit the unpins in new ways since the key-piece has also unguarded d4 and b4. 1…Sd3 2.Qe3 (not 2.Qe5?) and 1…Sf5 2.Qe5 (not 2.Qe3?). Another changed mate occurs with 1…e5 2.Bxb6, utilising the opening of the sixth rank in both directions. Lastly, 1…Rd6 permits 2.Sb7. Three good changed mates, two with dual avoidance effects.

Andy Sag: The key abandons set mates after two queen unpins and sixth rank line clearance. The fourth defence 1…Rd6 unguards b7 and also refutes the try 1.Se5?

George Meldrum: The line 1…Sd3 2.Qe3 is particularly nice.