Longer half-pin problems
Report by David Friedgood
The first problem is a straightforward one – the half-pin is ready for
action in the start position on the diagonal c1 to f4.
[Event "1 Pr 64-Shakhmatnoe Obozrenye"] [Site "?"] [Date "1982.??.??"] [Round
"?"] [White "V Rudenko & M Marandyuk"] [Black "Mate in 3"] [Result "*"] [Annotator
"David Friedgood"] [SetUp "1"] [FEN "8/6Np/Kp4p1/2p3P1/2RPpkNP/4bP2/2BrP1Q1/2Bn1r1n
w - - 0 1"] [PlyCount "5"] [EventDate "1982.??.??"] 1. Qh3 {Threatening 2.Ne6+
Kf5 and then mate by any move of the Ng4. The thematic defences capture the
Pd4 so as to create a potential flight square for the king on e5:1...} Bxd4
({The second thematic variation is} 1... Rxd4 2. Bxe4 {threatening 3.Ne6#} Rd6
3. Bd5# {The Bd5 shuts off the rook, preventing it from interposing on d4, while
the bishop is pinned and helpless to interfere }) (1... cxd4 {is the only non-thematic
variation worth showing. The pawn now obstructs the black rook and bishop so
that after} 2. Ba3 {they are unable to prevent the bishop mating on d6}) 2.
fxe4 {Again threatening 3.Ne6#} Bxg7 3. e5# {The roles of the black rook and
bishop are now reversed by comparison with the 1...Rxd4 variation. The rook
is pinned and the bishop is shut off, this time by the Pe5. The play is 'quiet'
(White's second moves do not give check). The halfpin is exploited on the third
move and the echo variations unify the problem effectively.} *
The second problem, a fourmover, also has the half-pin set up in the diagram,
but the idea of the composers is not so much to exploit the pinning of the pieces
as to decoy both of them off the half-pin line to be able to control a square
in the black king’s field.
[Event "2nd Pl USSR Championship"] [Site "?"] [Date "1982.??.??"] [Round "?"]
[White "E Bogdanov & L Makaronez"] [Black "Mate in 4"] [Result "*"] [Annotator
"David Friedgood"] [SetUp "1"] [FEN "2Q4B/bK2P3/1p1p1r1r/1R2n1N1/3k4/1p1p4/5Pp1/5b2
w - - 0 1"] [PlyCount "7"] [EventDate "1982.??.??"] 1. Qc1 {Threatens 2.Qb2+
Kc4 3.Qxb3+ Kd4 4.Rd5# 1...} Rxf2 {Now the knight is left pinned. However, in
both thematic variations it is not only the pin that White uses, but also the
ability to prise open the diagonal controlled by the Bh8.} (1... Nc4 2. Ne6+
Ke4 3. Qf4+ $1 Rxf4 4. Ng5#) 2. Rb4+ Kd5 3. Qc4+ $1 Nxc4 4. Rb5# {A simple but
exceptionally elegant concept. In each variation White decoys both black half-pinned
pieces off the half-pin line, sacrificing the queen and executing a switchback
mate (the rook and knight return to their original squares in the diagram to
effect mate).} *
The last two diagrams are for the reader to solve. In each case, you have to
find the unique key move, which forces mate on White’s third move. For
each black defence to the threat you have to find the continuation for White,
Black’s response(s) and finally the mate.
White to play and mate in three
In the above problem, the half-pin has yet to come into being. It’s quite
easy to find how Black can be induced to inadvertently create the half-pin by
an appropriate key and threat. Then the question is how to exploit the half-pin.
White to play and mate in three
This problem has a solution in which the half-pin is activated before it exists!
You should be able to see from the diagram how the half-pin might come about,
but the sequence of moves might surprise you.
Solutions to the two problems
[Event "1 Pr Themes-64"]
[Site "?"]
[Date "1980.??.??"]
[Round "?"]
[White "Jean Morice"]
[Black "Mate in 3"]
[Result "*"]
[Annotator "David Friedgood"]
[SetUp "1"]
[FEN "8/pp4Kp/qb2p3/1P2k1p1/1B2n1P1/1r1QP2r/B2PR1N1/4N3 w - - 0 1"]
[PlyCount "5"]
{The pleasing, if slightly obvious key is} 1. Qd8 {with the threat of 2.d4+
and mate next move. If} Bxd8 ({The thematic variations feature captures of
the
pawn on e3, thus creating a halfpin with the capturing piece and the knight
on
e4 on the line of the rook on e2.} 1... Bxe3 2. d4+ {White's strategy is to
decoy the piece on e3 away, so as to leave the knight pinned.} Bxd4 3. Qxg5#)
(
1... Rbxe3 2. Nd3+ Rxd3 3. Qf6# {Note that this mate is possible as the rook,
in capturing on e3, opened the line of the bishop on a2 to take over
protection of d5.}) (1... Rhxe3 2. Nf3+ Rxf3 3. Qd6#) 2. d4+ Kd5 3. Bxb3#
{An
elegant problem, but the half-pin is incomplete (there is no variation where
the knight moves leaving the piece on e3 pinned) and the 1...Bxe3 variation
is
met by the first move of the threat.} *
[Event "1st Pl League of Macedonian Problemists"]
[Site "?"]
[Date "2006.??.??"]
[Round "?"]
[White "Aaron Hirschenson"]
[Black "Mate in 3"]
[Result "*"]
[Annotator "David Friedgood"]
[SetUp "1"]
[FEN "1B1q2B1/2r5/3r1p2/N4kPp/1p3N1P/4pK2/6PP/Q5b1 w - - 0 1"]
[PlyCount "5"]
{The key is very easy - you only have to spot the idle pawn on h2!} 1. h3
{
threatening 2.g4+} {Black's two defences create a flight square for the king
on e5:} Rc3 (1... Rd4 2. Be6+ {Avoiding 2.Bh7+? Rxh7} Ke5 {The king arrives
on
the half-pin line! This odd situation, where the king does not start off on
the half-pin line, has led to the term 'anticipatory half-pin'} 3. Nc4#) 2.
Bh7+ {Avoiding 2.Be6+? Rxe6} Ke5 3. Nc6# {A clear illustration of the
anticipatory half-pin. Both mates are double pin-mates. The too simple key
is
a pity.} *
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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