Black unpins White

Arnoldo Ellerman (12.01.1893-21.11.1969), an Argentine, was a prolific composer of two-movers. He showed many Black line-themes (interference and shut-offs) in the Good Companion problem folders. Here, the theme is Black unpinning White, not out of kindness, but to avert a threat. This will cause another defect in the Black position, allowing precisely separated mates.

1. Qh1! [ Threat >2. Qf3#]

1. ... Rd4 Interference with dark sq bishop allowing 2. Sf6#

1. ... Rc3 Interference with dark sq bishop allowing 2. Sf6#

1. ... Rd3 Interference unpin of white rook 2.Shut-off (of Rd3), discovered mate 2.Re3#

1. ... Bxe2+ 2. Bxe2# is not thematic

1. ... Rc4 Interference unpin of white rook 2.Shut-off (of Rc4), discovered mate 2.Re4#

1...Bb7 Withdrawal unpin of white rook 2.Shut-off (of Bb7), discovered mate 2.Re4#

1. ... Bc8 Withdrawal unpin of white rook 2.Shut-off (of Bc8), discovered mate 2. Re6#

1. ... Kg4 (a flight granted by key) 2. Qf3#

The beauty of the problem is the combination of the two ways in which a line-piece may be unpinned, by interference and by withdrawal. It will pay for newcomers to play over these beautiful variations.

Cross-checks, King flights, in the two-mover

Click on the 1.? after you have tried to solve it.

The main threat with the key is 2.Qxe4 mating, (the key paves the Queen's control on the e6 square initially obstructed). However, the main play is that the key sets up a surprising strong line of attack on the white-king, allowing the Black king to give as many as three discovered checks. These may be termed a royal battery, the King being the firing piece and the queen giving white check from the rear. For each, White's checkmating reply is separately forced as we shall see soon. This sequence where B gives W check, and W checkmates right back is called a cross-check. (As many as five cross-checks have been shown in a single problem, a "task".)

If 1...Ke6 ch, 2. Sc5 is dbl ch and mate. The knight blocks the discovered check of black, arriving on c5, it discovers double check from the light-sq bishop, and the king cannot move to the seventh rank, since the knight had also discovered the W Q's guard of e7!

If 1...Kg6 ch, 2.Se5 ch mates, (e5 interposes the check), g7 is not a run-out for His Majesty, since W Q's guard on g7 has been discovered, and B does not have QxS which is illegal(!) since Her Majesty is pinned upon this King flight by WR on g2.

If 1...Kxf4 ch, 2.Sd5 dbl ch mates (d5 interposes the check), it is dbl ch, discovered from the Rook battery down the f-file this time, and e3 square is diabolically covered by the checking Knight.

Slightly less thematic, but still cute, is the last variation 1...Qxf4, not a cross-check or a King flight. Now 2.Sb8 mates. The king cannot run to f4 on account of the "self-block", and the action to prevent the black rook line on the eighth rank is called a shut-off mate.

Helpmate in 28

This one is for sheer fun, possibly the longest helpmate ever devised.

Newcomers, please recall that in helpmates, Black moves first and is cooperating in finding a single variation in which white may deliver checkmate in the stipulated number of moves. However, neither side may move into check, (or move a pinned piece leaving their king in check, or otherwise make a illegal move). In the final checkmate position, standard rules apply.

Note: it is a bit unusual for Black king to be in check in a position, but it is Black to play first, and neither side may make a illegal move, so the first Black move is forced. The rest is forced by the logic that Black has to navigate the minefield of white pawn controlled squares, while creating a passer to promote to allow White to promote. All of this takes 28 dance steps.

Bristol Theme

This problem was composed in 1917. The first appearance of a long-range clearance move (a white piece making way for a like-moving white piece to barrel down the same line was shown by Frank Healy in a three-mover setting in 1861 in a composition tourney in Bristol. Hence the theme came to be known as Bristol.)

The key is somewhat surprising if you have not seen this type of paradoxical idea before. The bishop retreats all the way to the other corner anticipating someone else coming from h8 to b2. 1.Ba1. Black has no choice. 1...Kxg2. Now white promotes to queen. 2. h8=Q. Again, Black has no choice 2...Kf2. Now, we see the point of the clearance. 3. Qb2#. Note how the King at e4, the black pawn at g3, all have their roles in restricting the black monarch's freedom. There is one forced line of play throughout.

The Bristol theme here was characterized by Bh8->Ba1, and then Qh8->Qb2

For more examples with Bristol moves used multiple-times in the same problem, in post-key phase, in try play, or in helpmates, see the excellent ozproblems page on Bristol

Sam Loyd, puzzle king

The first thing you do in a "mate in two" problem, is the examine the "set" play. This means you pretend it is Black to move first, and you find checkmate moves for White

Set Play:

1. ... d5 2. Sc5#

1. ... b2, Sb4/a3/e3/e1 2. Q(x)b4#

1. ... Ra3/b2 2. S(x)b2#

In this problem, every legal black move has a White mate provided in the initial position. Such a position is called a "block". Sometimes, to preserve the character of a block problem, you try to find a quiet White move, that keeps Black in this trouble. Can we do that here? Let us see. If Bd1 moves, Black can now play b2, and there is no pin on the knight(S) at c2, no mate Qb4. If Bxc2, Sxc2. Strong checking moves by the Queen are useless, since 1.Qa7ch? Kb5 and the king escapes. The White rook cannot move gainfully. It releases the e-pawn 1...e5+ by Black would not be nice. How do we find a quiet move?

Some more terminology for future use. Neither the Black p at b3 nor S at c2 are pinned, but they can be said to be half-pinned. A great English composer Comins Mansfield, made many problems where the main line of play uses halfpins. Entire books have been written about problems with half-pins "Het Half-pin thema" in Dutch.

Have you solved it yet?

Sam Loyd was one tricky guy. The key move does not preserve the quiet. It introduces a threat. Such problems with a block in the set play and a threat in the "key" (the solution's first move) are called "block-threat" problems and are both rare and difficult to solve. Here the key is 1.Sa3! (>2. Threat Qa7#) (By covering b5, the threat is set up for the mate.) Here are the variations

1. ... Kxa3 2. Qa5/a7#

1. ... b2, Sb4/xa3 2. Q(x)b4#

1. ... Rxa3 2. Sb2#

Pal Benko, twin problem, helpmate in 7

Sometimes a helpmate problem, especially in a longer move setting, need not be a serious affair. There is a pretty picture in this helpmate which is a twin (a nearly identical position), the stipulation being, to remove the bishop at h4 in the last diagram. Here, also, we have a pawn promoting all the way from second rank, under-promoting, else the black king scampering to h1 would be in check. The long journey undertaken by a promoting pawn in chess problems is called Excelsior.

Pal Benko, helpmate composer

Multi-time world champion Candidate, Pal Benko, not only composed studies, but also more-movers and problems in chess helpmates. From his book with Silman, the wonderful "My life, games and compositions" comes the first of two twins. Black moving first is to help White to mate him. See the dance of the under-prmoted black rook as it races to strangle his own monarch.

A twin is a second problem with the same stipulation but a slight change in one of the pieces. Here, remove the h4 bishop from the board, and again it is a helpmate in 7 with a different solution

In Memoriam Svetozar Gligoric