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.
