Chess Problems: Obstruction and Paralysis – solutions

7/15/2012 – In his last column problem expert David Friedgood explained a special theme: paralysis. This occurs when the defending side is forced to not just one square is blocked, but all the squares available to a piece. The author explained the concept with two examples and gave us three interesting thematic problems to solve. Here are the solutions.

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Chess Problems: Obstruction and Paralysis

By David Friedgood

In my recent article on Obstruction and Paralysis I set three examples for readers to solve. The first was a two-mover by Michael McDowell, which he sent as a counterexample of my statement that it is not possible to show the theme of obstruction in a two-mover. Let us first see the solution:

[Event "The Problemist"] [Site "?"] [Date "1993.??.??"] [Round "?"] [White "Michael McDowell"] [Black "Mate in 2"] [Result "*"] [Annotator "David Friedgood"] [SetUp "1"] [FEN "b7/3QR3/8/8/5k1B/8/8/4K2R w K - 0 1"] [PlyCount "3"] [EventDate "1993.??.??"] {The key is} 1. Qe6 {with the threat as below. There are just two variations, the thematic one being} Kf3 ({Threat:} 1... -- 2. Rf7#) (1... Be4 2. Qxe4#) 2. O-O# {The point of the problem is to show a mate by castling with optimal economy. A problem such as this, with a maximum of 7 units including the kings is known as a miniature.} *

Michael accompanied this problem with a note: “An interference prevents a piece reaching a square beyond the interference square [in this case f3], so it seems to me that 1...Kf3 is an obstruction [of the bishop].” In other words, the king is occupying a square which the bishop could otherwise occupy to ward off the check from the rook.

This might turn out to be a tricky philosophical issue, but it seems to me that, if the king is in check on f3 there is no question of interposing a piece on f3; therefore, the king is not obstructing the bishop from interposing between it and the rook. I do understand that Michael is drawing a parallel between interference by the king, which can be shown in a two-mover, and obstruction by the king. However, I think that parallel is false. But I could be wrong and anyone wishing to enter the fray on this discussion is welcome to do so!

[Event "Praca"] [Site "?"] [Date "1959.??.??"] [Round "?"] [White "K Ahlheim"] [Black "Mate in 3"] [Result "*"] [Annotator "David Friedgood"] [SetUp "1"] [FEN "6n1/7p/5p2/p1p2Ppr/2R3pk/6p1/2Q1P1P1/7K w - - 0 1"] [PlyCount "5"] [EventDate "1959.??.??"] 1. Kg1 $1 {threatens mate as below.} ({The immediate} 1. Rxg4+ $2 {allows} Kxg4+ {with check!}) 1... Nh6 {protects g4, but now the rook on h5 is paralysed and White can take advantage of this cleverly:} ({Threat:} 1... -- 2. Rxg4+ Kxg4 3. Qe4#) ({Black can also defend against the threat by vacating h5: } 1... Rh6 {, but this obstructs the knight and after} 2. Qe4 {there is no way to prevent mate by (e.g.} Kh5 {)} 3. Qxg4#) 2. Qa4 $1 {threatening nothing but bringing about zugzwang. Black can only move the knight and that allows e.g.} Nxf5 3. Rxg4# {A fine little problem combining paralysis with obstruction and also showing the 'doubling' of queen and rook, first with the queen behind and then with the queen in front.} *

[Event "Die Welt"] [Site "?"] [Date "1962.??.??"] [Round "?"] [White "E M H Guttmann"] [Black "Mate in 4"] [Result "*"] [Annotator "David Friedgood"] [SetUp "1"] [FEN "8/1R2R3/8/8/2p5/2P5/pppp4/1rbk3K w - - 0 1"] [PlyCount "3"] [EventDate "1962.??.??"] {My hint to solvers was that White's plan is to move the e-rook somewhere on the e-file, so as to allow the other rook to mate on the first rank via f7 or g7. In fact, the only correct move is} 1. Re4 $1 {This anticipates} a1=Q (1... a1=B $1 {is Black's main defence, using paralysis as a defensive weapon! White now has to ditch the original plan and think again, because stalemate is imminent:} 2. Rf4 $1 Ke2 3. Re7+ Kd3 (3... Kd1 4. Rf1#) 4. Rf3#) 2. Rf7 $1 { Now mate is forced, as the Re4 prevents Qa8+} ({Not} 2. Rg7 $2 Qa7 $1) *

This closes my brief survey of Obstruction and Paralysis. Next time we’ll start to look at one of the most fertile areas of problemdom: pins.

Any queries or constructive comments can be addressed to the author at david.friedgood@gmail.com.

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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