Weekly Problems 2026-B

The white king has four diagonal flights, and the two eventual mating moves by Black’s queen and e8-bishop will cover different pairs of these squares. In both cases, White needs to self-block the two remaining flights, so the rooks are unpinned for this purpose. The white queen and h7-bishop take turns to unpin one of them, which then frees the other. Once both rooks have carried out their self-blocks, the self-pinned queen or bishop moves along the pin-line to give a deflecting check, which forces a diagonal pin-mate. 1.Qh1 2.Qc6 3.Rd4 4.Rc4 5.Ra2 6.Ra6 7.Qd7+ Bxd7 and 1.Bg8 2.Bc4 3.Re6 4.Rc6 5.Ra7 6.Ra4 7.Bd3+ Qxd3. Two attractive sequences with perfectly matching effects, including how the rooks switch the lines on which they are pinned.

George Meldrum: Nice pair of complementary solutions. Had initially thought that a king march may have done the trick: Kc6-d6-e7-f8-g7-h6-h5, Qh3+ Qxh3, but alas that was eight moves.
Andrew Buchanan: Very satisfying. The unguarding and re-guarding of the white squares adjacent to the black king is particularly cute.
Satanick Mukhuty: Beautiful harmony of unpin and self-pin in the two phases!

In this complete block position, white mates are prepared against all possible black moves. Thus, 1…Q~ unpins the white queen and allows 2.Qd3, while 1…S~ is an unguard that enables 2.Rxb4. White has no way of preserving this zugzwang, however, and any king move (which creates threats) is foiled by a queen check, e.g. 1.Ka1? (2.Qd3/Bb1) Qd4+!, 1.Kc1? (2.Qd3/Bb1) Qc4+! The key 1.Sg2! (waiting) puts the knight in control of e3 instead of d3. This leads to changed mates for all three black queen moves, 1…Qd4 2.Qc2, 1…Qc4 2.Qxc4, and 1…Qxa4 2.Qd5, where the white queen must choose each mating square with care. 1…S~ 2.Rxb4 is unchanged. An unusual mutate in which one unpin variation in the set play is expanded to three after the key.

Bob Meadley: 1.Sc2? a good try but 1…Qd4! Very tough for me and a nice simple looking position.
George Meldrum: A masterclass of changed play from set play.
Satanick Mukhuty: A great mutate with three mate changes achieved with just eleven units. The try 1.Sc2? also contributes to the content.

Three white pieces are controlling three different flight-squares on their own: the rook guards e5, the d3-bishop guards e4, and the knight guards c6. These pieces have a potential two-move mating sequence that unguards and re-guards the flight, namely …Rb4-b5, …Bb5-c6, and …Sc6-b4. Black’s rook, e8-bishop, and queen are impeding these mates, and different pairs of these pieces must sacrifice themselves for each sequence to work. 1.Rb4 [A] Rxb4 [a] 2.Bb5 [B] Rxb5 [b]. 1.Bb5 [B] Bxb5 [b] 2.Qc6+ [C] Bxc6 [c]. 1.Qc6+ [C] Sxc6 [c] 2.Rb4 [A] Sxb4 [a]. In the three solutions, Black replays three moves in a cyclic order, AB-BC-CA. White occupies three squares (same as those occupied by Black) in a cyclic order, ab-bc-ca, using changed pieces, and these labels also represent the cyclic captures of three black pieces. The capture of black force is usually incidental in helpmates, but here the effect is thematized in an original way.

If the white queen adds a guard on f4, that will threaten 2.Rg6, though 1.Qc1? is thwarted by 1…Sd2! The key 1.Qxc7!, with the same threat, triggers two pairs of thematic variations. In the first pair, Black’s queen and b6-bishop pin the white rook, but they cause a mutual interference: 1…Qd4 2.Se3 and 1…Bd4 2.Qf4. In the second pair, Black’s queen and b7-bishop cut off the white bishop (creating a potential flight on f5), but they also interfere with each other: 1...Qe4 2.f3 and 1…Be4 (pinning the white queen) 2.Rf4. The subsidiary line 1…e5 2.Qd7 further utilises the white queen, and 1…Bxc7/Be3 2.Se3 repeats a main variation mate. The standard Grimshaw theme employs a rook and a bishop that close each other’s line; here a pinned black queen takes the place of the rook, and the idea is doubled. The dual avoidances after 1…Bd4 and 1…Be4 – each pinning a different white piece – are especially pleasing, while 1…Qd4 and 1…Qe4 result in pin-mates.

George Meldrum: A barrage of new lines after the key. Love the pin on the white queen after 1…Be4 preventing a dual by stopping 2.Qf4 mate.

White’s mainplan is to shift the bishop along the path Be8-h5-g4 to mate. However, 1.Be8? fails to 1…Bc3 2.Bh5 Bf6+ (or 1…Ba5 2.Bh5 Bd8+). White must first implement a foreplan designed to neutralise that black bishop. 1.Bb5! threatens Bxe2-g4, against which 1…Bc3 is ineffective – 2.Bxe2 Bf6+ 3.Kh5 ~ 4.Bg4. 1…c4 is a weak defence since 2.Bxc4 carries a second threat on e6, forcing 2…Bd5 3.Bxe2 ~ 4.Bg4. The thematic defence 1…Sc3 obstructs the e1-bishop as planned, but 2.Be8? is still premature because the black knight can now counter with 2…Sd5 3.Bh5 Sf6. Another foreplan is required to neutralise the knight. 2.Bd7 threatens 3.Bxe6, and 2…Bd5 blocks the square that the knight wants to access. The mainplan 3.Be8 threatening Bh5-g4 is finally playable, and the new defence 3…e5 (4.Bh5? Be6) permits 4.Bd7+ Be6 5.Bxe6. White can’t switch the order of the two foreplans for a subtle reason. 1.Bd7? Bd5 2.Bb5 and if 2…Sc3? then 3.Be8 works by transposing to the main line, but here 2…c4! refutes as the pawn is protected by the black bishop.

George Meldrum: There looks to be other ways to achieve this, but only 1.Bb5 works.
Bob Meadley: Nice square blocker.

To mate the black king on its original square proves impracticable, e.g. 1.Bb3 Ra1 2.Rxe4 Ra5 is hampered by the queen, even though both flights on e4 and e5 are dealt with. The two solutions begin with flight-captures on these e-file squares, which help to bring the white rook and bishop into play. After 1.Kxe4, the potential mate …Rf4 cuts off the h6-bishop, so White wants to guard not only e5 but also e3 with a knight move. 1…Sxc4? does the job but deprives Black of a self-blocker for d5, leaving the poor option 2.Rd5 which inadvertently opens a line for the queen and disrupts the mate on f4. Thus 1…Sg4 is necessary for 2.Bd5 Rf4.

These dual avoidance effects by both sides (1…Sxc4? and 2.Rd5?) are perfectly matched in the second solution, which commences with 1.Kxe5. Now the potential mate …Bf4 cuts off the f1-rook, so the remaining knight should guard both e4 and f5. But 1…Sxd6? removes a self-blocker for d5, forcing the poor alternative 2.Bd5 which opens the rank for the a4-rook and prevents the mate on f4. White must choose 1…Sg3 to facilitate 2.Rd5 Bf4. The orthogonal-diagonal transformation involves two doubly-masked black lines to f4, and even includes a white Grimshaw on that square. The construction is flawless, giving an economical Meredith setting with no plugs (pure cook-stoppers) at all.

Andrew Buchanan: Different roles for different units, and dual elimination (white knight destination on 1st move, black piece to self-block on 2nd move). Queen instead of bishop on b8 eliminates cooks.
George Meldrum: Superb.

A black checking defence is initially unprovided – 1…Rxf8+ 2.gxf8=Q Kh1 and the rook obstructs a queen mate on f1. White can prepare for that check by placing the rook on the queen-side, but in each case Black seems able to induce a similar white self-interference, by mirroring the white rook’s move. 1.Rd2? Rd8! 2.Qxd8 K~ and 3.Qd1?? is prevented; likewise 1.Rc2? Rc8! 2.Qxc8 (3.Qc1??), 1.Rb2? Rb8! 2.Qxb8 (3.Qb1??). The key 1.Ra2! (waiting) cleverly thwarts 1…Ra8 by utilising the geometry of the board, when the queen finds an alternative route to the 1st rank: 2.Qxa8 Kf1 3.Qh1. There are plenty of additional variations, mostly accurate: 1…Rd8 2.Qxd8 K~ 3.Qd1, 1…Rc8 2.Qxc8 K~ 3.Qc1, 1…Rb8 2.Qxb8 K~ 3.Qb1, 1…Rxf8+ 2.gxf8=Q Kh1 3.Qf1, 1…Re2 2.Rxe2 Kh1 3.Qf1, 1…Kh1 2.Qxe8 Kg1 3.Qe1, and 1…Re7 (etc.) 2.Qf2+ Kh1 3.Qf1/Qg2/Qh2.

George Meldrum: Very unexpected first move by White.
Bob Meadley: Haven’t seen this one before! A lovely miniature.

The B + S battery aimed at the black king is not controlled by Black, so White can threaten a discovered mate by moving any of the pawns obstructing the knight. These eight pawns have ten possible moves (disregarding 1.d3 which blocks the diagonal), nine of which are thematic tries. 1.d4? (2.Sd2) weakens c3 and fails to 1…b2! when 2.Sd2+ allows 2…Kxc3; 1.c4? (2.Sc3) cuts off the white rook, then 1…Kd3! refutes since 2.Sc3+ creates a flight on d4; 1.cxb6? (2.Sc5) Rc4!; 1.d7? (2.Sd6) Re6!; 1.f7? (2.Sf6) Be5+!; 1.fxg7? (2.Sf6) Sxg7!; 1.g6? (2.Sg5) hxg6!; 1.g4? (2.Sg3) Rxg4+!; 1.f3? (2.Sf2) Re2! The remaining pawn move 1.gxh6! solves and it invites a check, though 1…Bxh6+ (or 1…Kd3) does not handle the threat, 2.Sg5. Seven actual defences enable the knight to fire the battery in other ways: 1…Sxd2 2.Sxd2, 1…Sxc3 2.Sxc3, 1…Rxc5 2.Sxc5, 1…Rxd6/Sxd6 2.Sxd6, 1…Sxf6 2.Sxf6, 1…Rxg3 2.Sxg3, and 1…Rxf2+ 2.Sxf2. Brilliant knight-tour task problem, in which the maximum eight moves by a knight first appear as separate threats, then again as post-key mates.

George Meldrum: Moving a white pawn to make space for the white knight was clear. Even after finding the solution, testing for the nine other white pawn moves which were all tries, was tricky.
Andrew Buchanan: What a unique problem! Cute that the diagram position is just legal.

Black’s 15 available moves are all visibly spent by the pieces to reach their diagram squares. White has made five moves with the pawns and b3-knight, plus three with the rook and two with the dark-squared bishop to sacrifice themselves on c6 and f6 respectively, leaving five spare moves. Black’s development relies on White’s prompt sacrifices, but 1.d3? freeing the white bishop cannot be played until the black bishop has reached c2. 1.a4 Sa6 2.Ra3 Sc5 3.Rc3 Se4 (other knight routes to d2 would impede White) 4.Rc6 bxc6 5.c3 Ba6. White needs to waste five moves, an odd number task that cannot be allocated to the knights or the confined h1-rook, since oscillating them will use up an even number of moves. Only the queen is able to execute a five-move trek, though its exact path is not easily determined, e.g. 6.Qc2? Bd3 7.Qb3 Bc2 and the piece cannot return to d1 in time. After 6.Qb3 Bd3, the route Qa2-a1-b1-d1 will be blocked by Black’s bishop landing on c1, so the queen must get back via d2. 7.Qd5 Bc2 8.d3 Qb8 9.Bg5 Qb5 10.Bf6 gxf6 11.Sd2 Bh6 12.Sb3 Bc1 13.Qg5 Sh6 14.Qd2 0-0 15.Qd1 Sd2. The queen makes a five-move round-trip purely to lose a tempo, with some long-range play and no retracing of its steps.

Andrew Buchanan: The black move count is clear but there’s five white moves that are invisible – a suspiciously odd number. A very pretty and solvable proof game.
Jacob Hoover: The queen performs quite the elaborate rundlauf, visiting both sides of the chessboard before returning to d1. Also, the black dark-squared bishop and the white queen perform a bi-colored Bristol.

The black king is nearly hemmed in and we might assume that it gets mated unmoved. A possible scheme is to play Sf1, Qf5-f4-g3 to permit a queen mate on h6, but it takes five moves to promote the b-pawn on c8 (after 3.Bc6+ bxc6) and the white piece cannot reach h6 in time. Alternatively, the queen could mate on d8 if h5 were blocked by the bishop instead. This idea requires Black to sacrifice the queen on c6 to enable the promotion, without the piece giving a disruptive check en route. 1.Ba4 b4 2.Qe8 b5 3.Qc6+ bxc6 4.Bb5 c7 5.Be8 c8=Q 6.Bh5 Qd8. An unusual clearance manoeuvre by the two black pieces. The bishop starts by moving in the “wrong” direction (passing the critical square c6), then it makes a waiting move to b5, returns to e8, and finally reoccupies the queen’s square. The queen begins by occupying the bishop’s square, then continues following the other piece to reach the critical square.

Satanick Mukhuty: The basic plan is obvious enough: replace the queen on h5 with the bishop to enable mate along d8-h4. The execution, however, is pleasing, with a Bristol clearance and a not-so-obvious tempo move!
George Meldrum: Nice clearances.
Bob Meadley: It’s rare for me to pluck a Feather. The man is a master craftsman.
Andrew Buchanan: Very entertaining!

A flight-move by the black king to d3 is met by a queen mate on e2. Some of the black rooks’ moves also have set replies, such as those that allow a knight mate on e5 or b2. White must provide for Black’s remaining options. 1.Qe2? entails a double-threat, 2.Se5/Sb2, but 1…exd3! is still unaccounted for. 1.Qd1? threatens 2.Qxb3, and this is defused by 1…Rdxb5! The ambush key 1.Qg2! (waiting) not only aims at e4 and c2 (like 1.Qe2?), but also prepares the queen for 1…exd3/e3 2.Qxd5. The flight variation 1…Kxd3 2.Qe2 is as set. Each black rook now guards against a queen mate and a knight mate; when compelled to move, the piece cannot maintain its defensive “focus” along two perpendicular lines. 1…Rd~rank 2.Qxe4, 1…Re5 2.Sxe5, 1…Rd~file 2.Se5; only 1…Rdxd3 counters both focal mates, but the self-block enables 2.Rc5. Similarly, 1…Rb~file 2.Qc2, 1…Rb2 2.Sxb2, 1…Rb~rank 2.Sb2, and the self-block 1…Rbxd3 prompts 2.Rb4. A fine focal play problem showing perfect accuracy, in that not a single black move is followed by a dual mate.

George Meldrum: The placement of the two black rooks makes the problem look unsolvable. The key is a very quiet move.
Bob Meadley: This was tricky. Looks like Henry Bristow had a small booklet out in the early 1900s, Chess Miniatures, published by The Chess Amateur.
Andrew Buchanan: What an excellent puzzle! Amazing that it found its home in a boys’ magazine.

Initially, Black has only three legal moves by the e-pawn, two giving a double-check. White continuations are prepared for all of these defences. After 1…exd5+, 2.Kf4 keeps control of e5 and puts Black in zugzwang, then 2…d4 permits 3.Se4 (not 2.Kd4? stalemate). Similarly, 1…exf5+ 2.Kd4 f4 3.Se4 (not 2.Kf4?). If 1…e5 threatening stalemate, White exploits the opening of the 6th rank with 2.Sb3 (creating another zugzwang) axb3 3.Ra6. White has no starting move that could preserve all of these set variations, however, e.g. 1.Kf4/Kd4? e5+!, 1.c6? e5! (A further try 1.d6? threatens 2.Bxe7, but 1…exf5+! gains a flight on e6.) The waiting key 1.Sb3! discards the prospective knight mate on e4, but also pre-empts any stalemate bid. The two black checks now lead to 1…exd5+ 2.Kd4 axb3 3.Ra6 (not 2.Kf4? d4) and 1…exf5+ 2.Kf4 axb3 3.Ra6 (not 2.Kd4? f4), which represent a reciprocal change of White’s 2nd moves compared to the set play. A third change occurs after 1…e5, when despite the apparent zugzwang (2…axb3 3.Ra6), White must switch to making a threat, 2.d6 axb3 3.Bxe7. Lastly, there is an added variation, 1…axb3 2.Ra6 b2 3.Rxe6. A superb three-move mutate that features black double-checks, a complete change of white continuations including a reciprocal change, and a sacrificial key.

Jacob Hoover: A rather nice block-mutate indeed.
George Meldrum: A complete block position with White unable to lose a move in an intriguing setting. The solution changes all moves from that in the set play. A potential alternate solution is 1.cxb6 e.p. allowing the white rook to manoeuvre on the c-file in answer to 1…e5. However, this can be discounted due to the lack of proof of Black’s previous move.