Chess Problems: Obstruction and Paralysis

7/7/2012 – In his last column problem expert David Friedgood explained a special theme: obstruction. This occurs when a piece moves to a square so that another piece is prevented from occupying it. Today it is about paralysis, where not just one square is blocked, but all the squares available to a piece. The author explains the concept with two examples and gives us three problems to solve.

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Chess Problems: Obstruction and Paralysis

By David Friedgood

In my solutions to the problems for solving on the theme of Obstruction, I introduced the theme of Paralysis. I promised a further look at this theme, which is a special case of Obstruction, where not just one square is blocked, making it inaccessible to a defending piece, but where all the squares available to a piece are blocked. The piece thus paralysed is prevented from moving away from its location and this causes the defending side much discomfort.

Note that some cognoscenti prefer to use the term ‘incarceration’ (‘imprisonment’; German: ‘Einsperrung’) instead of ‘paralysis’. You may well agree that this picturesque alternative is more accurate.

The following problem is a very clear example of paralysis, showing two pairs of variations on the theme:

[Event "3rd Prize British Chess Federation"] [Site "?"] [Date "1958.??.??"] [Round "?"] [White "L I Zagoruiko"] [Black "Mate in 3"] [Result "*"] [Annotator "Friedgood,David"] [SetUp "1"] [FEN "6R1/2Bp1K2/8/4pNN1/3prk2/b2p1rpB/2nPpqn1/3b4 w - - 0 1"] [PlyCount "5"] [EventDate "1958.??.??"] 1. Nh6 {Black can now defend against the threat (see next line) by vacating f3 or e4:} Rfe3 ({Threat:} 1... -- 2. Ne6+ dxe6 3. Rg4#) (1... Ree3 {Vacating e4, so as to tie the Ng5 to its protection.} 2. Bf5 {taking back control of e4 by the bishop and freeing the Ng5 to threaten unpreventable mate by} -- 3. Nh3# { The Rf3 is paralysed and unable to free the f3 square for the king.}) (1... Nce3 {defeats the threat by guarding g4, but it paralyses both rooks, enabling White to threaten mate with the Ng5 in the knowledge that the knight can relinquish control of f3 and e4.} 2. Be6 $1 {vacates h3 to enable unpreventable mate by} -- 3. Nh3# {Note how the bishop has chosen the destination square carefully to avoid a check from the Bd1}) (1... Nge3 {again paralyses both rooks, but this time a threat of mate by the knight on h3 can be met by 2...Qg2, so} 2. Bxd7 $1 {threatens mate on e6 as well as h3 and there is no defence.}) 2. Bg4 {Black has played the only move to vacate f3, but in doing so has paralysed the Re4. Black is therefore again helpless to deal with the threat of immediate mate by} -- 3. Nh3# {, as it is impossible to vacate e4 to give the king a flight square.} *

Incidentally, the composer is famous for his association with a very important, modern two-mover theme that bears his name.

The next problem shows the related theme of Partial Paralysis, in which the partially paralysed piece is able to move, but only to a square or in a direction that causes damage to Black. This is a joint effort by Leonid Zagoruiko and Mark Libiurkin, better known as one of the giants of endgame study composition.

[Event "1st Prize Latvian Sports Committee"] [Site "?"] [Date "1950.??.??"] [Round "?"] [White "L I Zagoruiko & M Libiurkin"] [Black "Mate in 3"] [Result "*"] [Annotator "Friedgood,David"] [SetUp "1"] [FEN "8/1B6/1K1N2PQ/1PRpp2p/b2k2p1/4p2p/4P3/n7 w - - 0 1"] [PlyCount "5"] [EventDate "1950.??.??"] 1. Qf8 {To defend against the threat (see next variation) Black can guard f5 or c4 with the bishop, or interpose on d4 with the knight. Lets see what happens.} Bc2 ({Threat:} 1... -- 2. Nf5+ Ke4 3. Rc4#) (1... Bb3 2. Qf1 Nc2 { The knight has been partially paralysed by the bishop's occupation of b3, so, to escape the queen's attentions, it is forced to move to the only available square.} ({The threat is} 2... -- 3. Qxa1#) 3. Qd1# {It turns out that the knight has interfered with the bishop's guard on the d1 square, permitting the queen to mate}) (1... Nc2 2. Bxd5 -- $140 {The knight has obstructed the bishop on c2 and it is no longer possible to prevent} (2... e4 3. Qf6#) 3. Nf5# ) (1... Nb3 2. Qc8 -- $140 {Now the knight's obstruction of the bishop on b3 has prevented it from protecting d5} (2... Nxc5 3. Qxc5#) 3. Rxd5#) 2. Qa8 { This variation is an exact echo of the 1...Bb3 variation. Again the threat is to mate on a1 and again the knight is semi-paralysed and can only move to b3, where it interferes with the bishop:} Nb3 3. Qa4# {A very clever and rather beautiful problem, showing partial paralysis and obstruction. The agility of the queen is a notable feature.} *

There are three problems for solving this time. The first was sent to me by Michael McDowell, who claims it is a counterexample to the statement in my original article on Obstruction."In a two-mover, the self-block of the king is the only obstruction that is feasible". Would you agree with Michael?

    Mate in two

To solve this problem you have to find White’s first (‘key’) move, which is the only one to force mate on the second move whatever Black tries to do about it. This move will threaten mate and all Black’s defences will create some weakness, allowing White to mate.

    Mate in three

You have to find White’s key move, which will threaten to force mate in a further two moves. Again, Black’s defences to the threat will allow White to meet them with continuations that take advantage of the weaknesses they create – obstruction and paralysis should be borne in mind.

    Mate in four

You have to find White’s key move, which will threaten to force mate in a further three moves at most. Since this is a four-mover, I’ll give you a hint. White’s general strategy is to move the Re7 somewhere on the e-file, keeping the black king penned in. This will make way for the other rook to give mate on the first rank via f7 or g7. Note that this uses only three of White’s available four moves, so intervention by Black will have some impact that you will need to deal with.

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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