Chess Problems: Solutions to the half-pin problems

9/14/2012 – Were you able to solve the two problems with the half-pin theme? It should have been possible after our problem expert David Friedgood explained the idea – two chess pieces are half-pinned against the king and one of them moves, then the other becomes fully pinned – with two introductory problems. Today he carefully explains the solutions to the diagrams he left our readers to solve.

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Chess Problems: Solutions to Half-pin Problems

By David Friedgood

Last time I discussed the Half-pin Theme and set a couple of examples for solving. Today’s article gives the solutions with comments.

[Event "L'Italia Scacchistica"] [Site "?"] [Date "1919.??.??"] [Round "?"] [White "Antonio Bottacchi"] [Black "Mate in 2"] [Result "*"] [Annotator "Friedgood,David"] [SetUp "1"] [FEN "B3N1K1/1n1p2B1/2r5/3k4/Q2N4/5P2/8/2b5 w - - 0 1"] [PlyCount "3"] [EventDate "1919.??.??"] {The methodical way of solving this problem would begin by noting that there is a flight square on c5, and that if it were Black's move then 1...Kc5 has a mate already set by 2.Qb5#. This is what the composer would like you to see, as it delays your finding the key move, which changes this set-up quite radically. On the other hand, an experienced solver, seeing that the d4 knight is laterally adjacent to the black king, would know that it is very likely to be the key piece. The main reason for this is that, by moving, the knight could land on a square from which it could deliver mate. And indeed the key is } 1. Ne6 $1 {giving up control of e6, but in exchange gaining control of c5 and threatening 2.Qe4#. Note that the threat still works after 1...Kxe6, partly because of the clever use of the white king to guard f7. Now the half-pinned pieces on b7 and c6 do their stuff, each making two variations by moving to protect e4: 1...} Rxe6 {(Continued as main line)} ({In the four thematic variations a half-pinned piece self-blocks and leaves its partner fully pinned:} 1... Rc4 2. Qxd7#) (1... Nd6 2. N8c7#) (1... Nc5 2. N6c7#) ({ The only non-thematic variation is also a self-block:} 1... dxe6 2. Qd4#) 2. Qb5# {This lightweight problem shows symmetrical play, not only in the geometrical sense but also in the thematic motifs in the variations.} *

[Event "Time and Tide"] [Site "?"] [Date "1952.??.??"] [Round "?"] [White "Comins Mansfield"] [Black "Mate in 2"] [Result "*"] [SetUp "1"] [FEN "2B1Q2K/8/5pp1/2N2P2/Rr2pk2/6R1/1r3p1B/4q3 w - - 0 1"] [PlyCount "3"] [EventDate "1952.??.??"] {For this problem, your solving can be aided by your knowledge of problem themes. The half-pin on the fourth rank is easily spotted, but is a little puzzling, as if the b4 rook moves upwards or 1...e3 is played, the same mate 2. Nd3# is possible. Also, the existence of the bishop/rook battery is odd, as there is no way it can produce a mate with the king on f4, given that the rook is tied down to covering four potential flight squares. However, if the white queen moves away, then 1...Ke5 would lead to 2.Rd3#. Clearly, the queen is going to make the key and it takes just a small imaginative leap to come up with the beautiful} 1. Qb5 $1 {This "ambushes" the queen behind the knight so as to threaten 2.Ne6# discovering protection of e5 and f5. The mate after} Ke5 {is in place (continued in main line)} ({The only two other defences are the thematic half-pin moves} 1... Rxb5 {allowing} 2. Nd3# {as already noticed in the set play}) (1... e3 {on the other hand cannot now be met by 2.Nd3 as there would be no protection of the e4 square. Instead there is a lovely pin-mate by} 2. Qb8#) 2. Rd3# {The half-pin here forms the core of the problem, but the key move, giving up a flight and offering the queen is the star turn.} *

There will be more about the half-pin theme in my next article. Any queries or constructive comments can be addressed to the author at

Copyright in this article David Friedgood 2012/ChessBase

The British Chess Problem Society (BCPS), founded in 1918, is the world's oldest chess problem society. It exists to promote the knowledge and enjoyment of chess compositions, and membership is open to chess enthusiasts in all countries.

The Society produces two bi-monthly magazines, The Problemist and The Problemist Supplement (the latter catering for beginners), which are issued to all members. Composers from all over the world send their problems and studies to compete in the tourneys run by the society.

The BCPS also organises the annual British Chess Solving Championship, and selects the Great Britain squad for the World Chess Solving Championship. The Society holds an annual residential weekend, with a full programme of solving and composing tourneys and lectures; this event attracts an international participation. Members are also entitled to use the resources of the BCPS library, and the Society book service, which can provide new and second-hand publications.

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