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 david.friedgood@gmail.com.
Copyright in this article David Friedgood 2012/ChessBase
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