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451. John James O’Keefe
Die Schwalbe 1933
Mate in 3

The black king has a flight-move that’s provided for, though another strong defence, 1…Bxc2, has no set reply. The thematic try 1.Rb2? threatens 2.Rb8 but 1…Bb5! refutes, since 2.Rxb5 is stalemate. The key 1.Se4! threatens 2.Sc5 and 3.Sb6 (which 1…Bxc2 doesn’t handle). Black defends by capturing the offered knight, 1…Bxe4, and now that the bishop is decoyed to the long diagonal, White can proceed with the original plan, 2.Rb2 (3.Rb8), because Black’s substitute defence, 2…Bb7, carries the weakness of self-block, permitting 3.Sb6. This three-move miniature hence exemplifies the Roman decoy theme. The flight variation is unchanged from the set play: 1…Kb7 2.c8(Q)+ Ka7 3.Rc7.

Andy Sag: A tricky miniature with a sacrificial key. Nice try is 1.Sb3? Be4!
Andrew Buchanan: The d2-knight is so far from the action it looks like it must move as the key.
George Meldrum: The far outpost knight on d2 begs to play. First attempt is stopped: 1.Sb3? Be4! Surprisingly then the knight finds its way to e4 in face of the bishop.

452. Barry J. da Costa Andrade
Chess World 1949
Mate in 2
Twin (b) After key of (a)

The diagram position is a complete block, where most black moves permit a knight mate on d5 or g2. The black queen is unable to maintain its focus on these squares: 1…Q~file 2.Sd5 and 1…Q~diagonal 2.Sg2; there are no duals when the queen lands on either mating square – 1…Qd5+ 2.Sxd5 and 1…Qg2+ 2.Sxg2 – though 1…Qh8 enables both mates. The f8-knight and h6-bishop cannot avoid interfering with the queen: 1…Se6 2.Sd5 and 1…Sg6/Bg7/Bg5 2.Sg2. Only the h1-knight elicits a different mate with 1…Sf2 2.Qxf2, while a dual follows 1…Sg3 2.Qf2/Sg2. White has numerous tries that aim to preserve the block but are subtly defeated by the black queen. 1.Bb~? Qxa2! and 1.f6? Qg5! allow the queen to keep its focus on the mating squares. Also, 1.Bh5? Qg4!, 1.Kb6? Qg1!, and 1.Ka6? Qxa2+! Only 1.a3! (waiting) solves. The unusual twinning calls for the position after 1.a3 to be solved anew with White to play. Again this is a complete block situation that White wants to retain, and now 1.Ka6! does the job, given that 1…Qa2 no longer checks.

When this problem was originally published, Frank Ravenscroft pointed out that it could be extended to three parts by transferring the b2-bishop to f6 in the diagram. The new (a) position would then be solved by 1.Bb2!, leading to the initial setting. Here 1.Bb2! completes the block (by providing for 1…Qxa2), unlike the other keys which maintain an existing zugzwang.

Andy Sag: The keys preserve set play but there are two duals.
George Meldrum: The fun in this complete block position comes from finding out what does not work and why.
Andrew Buchanan: The core geometry is a duel between the e3-knight and g8-queen, over control of g2 and d5. 1.Kb6? allows the beautiful 1…Qg1! 1.Bh5? suffers 1…Qg4! cutting off access to f3. If the other white bishop moves then 1…Qxa2! covers both of the key squares.
Ian Shanahan: The first key is irreversible; the second doesn't work in the first part because of check. Focal theme, with play unchanged. Cute!

453. Herbert Ahues
The Sun-Herald 1961
3rd Prize
Mate in 2

The key 1.Sd7! attacks f6 and threatens a battery mate, 2.Bh6. By opening the long diagonal, the thematic key also permits the d4-knight to give various discovered checks. A random placement of this piece, 1…S~+, allows the a4-rook to guard f4 and so admits the cross-check, 2.Bf6. The black knight has two correction moves that disable 2.Bf6 by controlling the white R + B battery, but these defences interfere with a black line-piece and lead to other cross-checks: 1…Se6+ 2.g7 and 1…Sf3+ 2.d4. Only three variations and the two white diagonal batteries (both unusually employing a pawn as the front unit) fire just once each, but the strategic intensity of the play makes this a case of quality over quantity.

Andy Sag: The key allows battery checks, all defeated by cross-checks. Adding a white pawn on h4 would be a slight improvement as it would give a true changed mate (set 2.Be7) for random moves of the knight.
Jacob Hoover: The key activates the black B + S battery on the long diagonal… There is no distracting by-play.
George Meldrum: A high-quality problem that sticks to its theme. A very minor flaw with the dual after 1…Be4.
Ian Shanahan: The key clears the line of a black battery directed at the white king, Good-Companions style. Old-fashioned for the date of publication, but timelessly beautiful nevertheless.

454. Laimons Mangalis
Die Schwalbe 1953
Mate in 6

The black king, though trapped in the corner, is also well protected, ironically because White’s bishops and pawns create a barrier that prevents any direct assault by the queen. A delicate approach is required to get the queen through this barrier, as White steers the black pawn on c6 into clearing a path for the piece. 1.Qa6! cxb5 2.Kb4 bxc4 3.Kc3 cxd3 4.Kd2 dxe2 5.Ke1 exf1(Q)+ 6.Qxf1.

Andy Sag: The long pawn chain is an obvious clue. What the pawn promotes to is immaterial. A very amusing one-liner.
Jacob Hoover: The queen flies down the now-open a6-f1 line for the mate.
George Meldrum: Too easy reduces the smile factor, nevertheless cute.
Nigel Nettheim: Amusing! The f6-pawn can be removed, if the e3-bishop is shifted to d4 [stopping the cook, 1.Qh8 cxb5 2.Kb4 bxc4 3.Qc3, etc.].
Ian Shanahan: The solution is spotted immediately, but the ladder mechanism is cute.

455. Alexander Goldstein
British Chess Federation Tourney 1955
4th Prize
Selfmate in 2

If White shifts the queen from the f-file to another square where it doesn’t control Black’s R + B battery, 2.Be3+ will be threatened, forcing 2…Bxe3. The choice of 1.Qd7! is natural, half-pinning the two black pieces, but it’s not obvious how White should proceed when Black captures the c4-knight with either piece (to answer 2.Be3+ with 2…Ke5/Sxe3!). Each capture by the bishop or the knight leaves the remaining piece on the d-file pinned, after which White wants to incapacitate the capturer on c4 in order to force Black to open the battery through zugzwang. Now pinning the c4-piece with one of the white rooks seems to create an unwanted flight on the second rank and spoil the battery mate. But it turns out that White can make such a pinning move by cleverly exploiting the position of the c4-piece, which has inadvertently placed a guard on one of the rook-squares, allowing it to be unblocked. 1…Bxc4 2.Ra4 Bg~ and 1…Sxc4 2.Rb4 Bg~. One other defence, 1…Sf5, is met by a grab, 2.exf5 Bg~.

Andy Sag: Tries: 1.Be3+? Bxe3+ 2.Qf1, and 1.c3+? Kxd3 2.Qxd5+ Ke2!
Jacob Hoover: In each of the main lines the capturing unit guards the square that the pinning rook vacates.
George Meldrum: The composer has clearly hung signs over the two rooks and pawn in front of the white king saying, “Do Not Disturb”. Little wonder a solver may go into panic mode before finding that both rooks are needed in variations. Deceptively good.
Nigel Nettheim: It took me two attempts to find the play, with the attractive use of the white rooks.
Ian Shanahan: The key establishes a half-pin, after which the piece that moves is pinned in the thematic play, forcing the bottom-rank battery to open due to zugzwang. Pretty strategy.

456. Frederick Hawes
The Australasian Chess Review 1944
1st Prize
Mate in 2

Initially Black has three legal moves, all of which are prepared with white mating replies: 1…d5 2.Se6, 1…c5 2.Qd3, and 1…f3 2.e3. White has no way of maintaining the block, however, and the key 1.Qb3! actually entails a threat, 2.Qb4. Two flights are granted by the queen, and when the king takes these flights, White answers with two of the mating moves seen in the set play: 1…Kc5 2.Se6 and 1…Ke4 2.Qd3. Hence the problem demonstrates mate transference. It’s a flaw that the set variation 1…c5 2.Qd3 is still effective, duplicating the thematic queen mate linked to the new 1…Ke4 defence. The transfer of the knight mate 2.Se6 is clearer because its original defence 1…d5, unlike 1…c5, doesn’t deal with the threat and so can be ignored. In any case, this is a splendid example of the block-threat form.

Andy Sag: Complete block with key giving two flights and threat replacing set play.
George Meldrum: A quiet, multiple flight giving key.
Nigel Nettheim: Two flights add to the difficulty of solving. The mate after 1…Kc5 is pure.
Ian Shanahan: A block-threat, whereby the key gives two flights – with mate transference. (It's a pity that the post-key mate 2.Qd3 is repeated.) What a superb and utterly memorable little Meredith problem! Bravo!

457. Linden Lyons
The Problemist 2015
Mate in 2
Grasshoppers a5, g8

The key 1.Gxc5! creates a R + G battery that can open in four different ways, and these moves function as multiple threats: 2.Ga5/Gc7/Gg5/Gg1. Four black defences induce each of the mating threats in turn: 1…Ga2+ 2.Ga5 (switchback and shut-off), 1…Gc8 2.Gc7 (shut-off), 1…Gg5 2.Gxg5, and 1…g5 2.Gg1 (recovering the g6-flight) – hence the Fleck theme is rendered. One more defence parries all of the threats by capturing the grasshopper, but provokes a new mate: 1…bxc5 2.Rxc5. Since Black employs the grasshopper in three of the main battery variations, this harmonious problem also features a G vs G duel.

George Meldrum: Grasshoppers take some getting used to. Opening the rook line while closing Black’s lines of defence is the theme, plus a nice response after Black plays 1…g5.
Jacob Hoover: Although the Fleck is a very nice touch, I think it would have been better if the four thematic defenses had all been grasshopper moves; that way the problem would display a nice bit of unity.
Ian Shanahan: A grasshopper duel, also showing a 4-fold Ideal Fleck theme – all threats separated by each black defence – with an elimination mate (transferred from the set defence 1…bxa5) thrown in for good measure. Fine construction!

458. Andy Sag
OzProblems.com 2019
Mate in 2

The thematic key 1.Re5! (threat: 2.Rd5) not only unpins the black queen, enabling it to check twice, but also shows a double-sacrifice of the rook. The first checking defence 1…Qxf5+ prompts a recapture, 2.Rxf5, that fires the B + R battery. The second check 1…Qc6+ is answered by the threat move, 2.Rd5, though this may be viewed as a distinct mate that requires the battery to operate again. If Black takes the offered rook, then 1…Qxe5 2.Se6 sees the queen re-pinning itself, while 1…Kxe5 permits 2.Qf4. The self-block 1…Rxc5 results in another pin-mate, 2.Re4. Lastly, the black knight admits a pair of queen mates that are nicely non-symmetrical: 1…Sc3 2.Qe3 and 1…Se3 2.Qb2.

Composer: Sacrificial give-and-take key unpinning the black queen. This allows it to give check answered by the threat but this time with a required double-check, and a second check answered by a battery mate.
Jacob Hoover: The key allows two checks from the queen, but each time White has a cross-checking answer.
Atagün Karayel: The c5-pawn was so much of an obstacle in all tries: Let's just protect it!
George Meldrum: The key provides a give-and-take flight and releases the black queen to attempt counter play.
Nigel Nettheim: A marvellous key. The white rook seemed likely to move to threaten Se6; that didn’t work, but the rook surprisingly moved anyway, to its least likely square and for a different purpose. Congratulations!
Bob Meadley: Nice two-mover by Andy.
Ian Shanahan: The unpinning key takes the unprovided flight but offers a flight-capture. Solid traditional work.

459. Rod Sutherland
The Problemist 1981
Mate in 3

White has no reply set against either of the black pawn’s moves, and the particularly strong 1…hxg2 would defeat 1.Bxb2? (threat: 2.Ra1). If White moves the a2-rook somewhere along the file (except a8), that deals with 1…hxg2 by preparing a rook mate on the h-file, and 2.Bxb2 becomes a threat. The black bishop’s defences on the long diagonal are mostly answered by its capture, e.g. 1.Ra7? Bd4+ 2.Bxd4 (3.Ra1) hxg2 3.Rh7, while 1…h2 permits 2.Rxh2+ Kxh2 3.Rh7; but Black cleverly refutes with 1…Bg7! since after 2.Bxg7 hxg2, the white bishop finds itself interfering with the rook’s mating move (or 2.Rxg7 fails to 2…h2). Likewise, 1.Ra6? Bf6! 2.Bxf6 hxg2 and 1.Ra4? Bd4+! 2.Bxd4 hxg2 are spoiling. Another tempting try is 1.Ra3? which handles 1…Bc3 with a new idea, 2.Rxc3 hxg2 3.Rh3 and 2…h2 3.Rc1, but now 1…h2! defeats as there’s no mate after 2.Rxh2+ Kxh2. The ingenious key 1.Ra5! (2.Bxb2) generates similar play to that of the tries after random bishop moves: 1…Bc3/Bd4+/Bf6/Bg7/Bh8 2.Bxc3/Bxd4/Bxf6/Bxg7/Bxh8 (3.Ra1) hxg2 3.Rh5, but here the interception move 1…Be5 can be exploited as an unguard that allows 2.Rg1+ Kh2 3.Bxe5. The remaining bishop defences, 1…Ba3/Bc1, also unguard e5 and prompt the same 2.Rg1+ (though a dual follows 1…Bc1 with 2.Rh5 also working). Lastly, 1…h2 gives 2.Rxh2+ Kxh2 3.Rh5.

Andy Sag: The short mates 1…hxg2 2.Rh5 and 1…Bxa1 2.Rxa1 detract slightly. Too many tries to mention but I like 1.Ra3? h2!
Jacob Hoover: Black has clever refutations for most of the a2-rook’s moves. The black bishop forces the white bishop to capture it on a square where it will be blocking the rook’s access to the h-file.
George Meldrum: A problem with many a choice of first moves, and a non-too obvious key.
Nigel Nettheim: Excellent. The a2-rook was bound to move, but where? A hard-to-find factor was needed: the weakening of e5 by 1…Be5 for an unexpected mating scheme.

460. Edwin John Eddy
The Australasian Chess Review 1933
4th Prize
Mate in 2

The key 1.Bd7! controls c6 and threatens 2.Qxa5, which remains effective after the flight-move, 1…Kxa4. Random moves by the a5-knight allow a potential dual, 2.Sxb4/Rb8, but these secondary threats are separated by 1…Sb7 2.Sxb4 and 1…Saxc6 (self-pin) 2.Rb8. The correction 1…Sc4 prevents both mates (besides the main threat) but self-blocks, enabling a battery mate that interferes with the g4-rook, 2.Sd4. All moves by the b4-knight also defend, by opening a line for the black bishop, and they lead to similar correction play. The potential dual after the knight’s random moves is separated by 1…Sd5 2.Sxa5 and 1…Sbxc6 (self-pin) 2.Rf5. Now 1…Sa6 disables both secondary threats, and the self-block error is exploited by another battery mate, 2.Sa7, which cuts off the white queen. Judges F. Hawes and J. J. O’Keefe called this problem, “A very charming echo-study, with a key-move weakness peculiar to symmetrical positions in general.”

Andy Sag: The key sets up a threat and a battery and if the trigger knight is captured, a pair of pin-mates result. The three pawns on second rank avoid all duals.
Nigel Nettheim: The key is too strong and therefore easy for a player to find but, paradoxically, harder for a problem-solver to find (“it wouldn’t be that!”).
Jacob Hoover: This problem has a lot of thematic elements to it that held my interest, and the symmetry between the black knights is a nice touch too.
George Meldrum: A less than ordinary key move. It does, however, create crisscross play by the black knights with amazing mirrored responses by White on different planes. Black pawns on the second rank appear to be placed to prevent duals. Modern practice, I am led to believe, is to exclude such pawns as duals are tolerated more than the extra material.
Ian Shanahan: The key-piece (initially out-of-play) sets up a direct battery. Both black knights make random moves and secondary corrections to defeat the threat in a matrix I’ve seen used several times since. A very elegant problem!

461. Norman Macleod
Chess World 1950
Mate in 3

Black’s only mobile unit is the c6-rook and immediate mates are set against its moves: 1…R~rank 2.Sc7 and 1…R~file 2.Sb6. White has no way of preserving the block, however, and the flight-giving key 1.Kg4! extends the solution to three moves. After 1…Ke4, 2.Bxc4 puts Black in zugzwang again, and now the focal play of the rook gives new mates: 2…R~rank 2.Sxc5 and 2…R~file 2.Sd6. If the rook defends on the first move, some duals result (either on White’s second or third move), e.g. 1…Ra6 2.Sc7+ Ke4 3.Sxc5/Bb1, but there are two dual-free variations, 1…Rd6 2.Sc7+ Ke4 3.Sxc5 and 1…Rc8 2.Sb6+ Ke4 3.Bb1.

Andy Sag: The key abandons the set block and gives a flight. If the flight is taken, a new block forces the rook to unguard at least one of the two mating squares for the b7-knight. If instead the rook moves first, the a8-knight checks to force the king into an ambush.
Jacob Hoover: A pseudo-two-mover. The problem clearly displays the focal theme, but the duals on the third move are unfortunate.
George Meldrum: The flight given to the black king reveals the pretty pattern of four black squares surrounding the rook and the interplay between the rook and knights.
Nigel Nettheim: A nice echo effect after White regroups.
Ian Shanahan: Changed focal theme, unusually set in a three-mover. The focal theme was a favourite of Norman Macleod in his earlier compositions.

462. Robert Lincoln
Australian Chess Problem Magazine 1996
Mate in 2

The diagonal half-battery arrangement – initially masked by the black rook – suggests that the first move will be made by one white rook, followed by battery mates delivered by the other. The thematic try 1.Re3? threatens 2.Rxa3, forcing the black rook to vacate the bishop line: 1…Ra7 2.Rd7 and 1…Rf3 2.Rf5; but 1…axb2! refutes. The key 1.Rd3! has a similar threat and draws the same defences, but creates new shut-off mates: 1…Ra7 2.Re7 and 1…Rf3 2.Rf6. Now 1…axb2 is answered by 2.Ra6. The e6-rook executes two more tries: 1.Ra6? Ra7 2.Rd7, but 1…Rf3!, and 1.Rxe2? (threats: 2.bP~) axb2 2.Qxb2 (an extra change), 1…Rf2 2.Rf5, but 1…Re7!

Andy Sag: A Meredith setting with potential battery indicating a rook key but which one and where to?
Jacob Hoover: A nice demonstration of the half-battery concept. That all the mating moves in the actual play are made by the same piece lends a degree of unity to the whole thing.
Nigel Nettheim: Very neat rather than very deep, perhaps.
Ian Shanahan: A very trying problem! Here we see, shown most elegantly, a masked half-battery in Meredith. This sort of set-up is rather hackneyed (there are numerous examples from the 1960s), but here is done in Letztform.

463. Christopher Jones
Australian Chess 2005
Helpmate in 3
Twin (b) Pd5 to b5

In part (a), a potential mate is to place the black king on f5 for Rf6. This scheme requires the e4-flight to be covered, but none of the spare white units can arrange to guard that square. Instead, Black blocks it with the d5-pawn, a move that necessitates two preparatory sacrifices. 1.Be3 dxe3 2.Kf5 e4+ 3.dxe4 Rf6. The twinning for part (b) shifts the thematic pawn to b5. With d5 vacant, the new plan is to mate the black king on that square with Sf6. Now the issue is how to deal with the c4-flight, and once again it has to be blocked by the black pawn, after sacrificial play by both sides. 1.Sc3+ dxc3 2.Kd5 c4+ 3.bxc4 Sf6. Like many other problems by its GM composer, this helpmate features pawn play that highlights a special property of the unit – its need to capture so as to access certain squares.

Andy Sag: The name Chris Jones strikes fear in the heart of the solver; his problems are always tough and this is no exception. In each case the d2-pawn was the only way to achieve the required self-block so the check from f6 could be a mate.

464. John James O’Keefe &
William James Smith

L'Eco degli Scacchi 1917
2nd Hon. Mention
Mate in 2

In this block position, all black moves are prepared with set mates: 1…Sg~ 2.Qe6, 1…dxc5 2.Sxc7, 1…R~ 2.Scxb4, 1…h1(Q) 2.Qxh1, and 1…Sb~ 2.Rd4 (with a dual, 1…Sxc5 2.Rd4/Sxc7). But White has no way of preserving all of these variations, e.g. 1.Re1/Re3? Ra2!, 1.Ke1? Ra1+!, 1.Kg3? Sh5+!, and 1.Qh4? which produces a change with 1…Sg~ 2.Rxf5, but is handled by 1…dxc5! The key 1.Qh8! (waiting) leads to three changed mates: 1…S~ 2.Qg8, 1…Se6 2.Se3, and 1…dxc5 2.Qd8. The remaining play is as set: 1…R~ 2.Scxb4, 1…h1(Q) 2.Qxh1, and 1…Sb~ 2.Rd4 (1…Sxc5 2.Rd4/Sxc7). A fine mutate with a particularly good ambush key that places the queen in the corner.

Andy Sag: A tricky waiter with a withdrawal key, changed mates and tries. The dual after 1…Sxc5 is unfortunate.
Jacob Hoover: The correction 1…Se6 is a self-block that allows the white self-interference 2.Se3.
Andrew Buchanan: Three changed mates; satisfying to solve. Dual after 1…Sxc5 2.Rd4/Sxc7, and no other variation provides the knight mate.
Michael McDowell: Whether it’s there by accident or design 1.Qh4? is a superb try, giving a neat change after 1…Sg~ while maintaining complete accuracy.
George Meldrum: Great key move with changed mates. Particularly nice response after Black’s knight to e6. Crafty methods used to avoid cooks, making it tricky to solve.
Ian Shanahan: A clever mutate with black correction by the g7-knight. Fine work by these regular collaborators.