[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "White to play and win"]
[Black "?"]
[Result "*"]
[Annotator "peter"]
[SetUp "1"]
[FEN "8/3p4/2pB3K/2P1Pk2/p1Pp4/5P2/3P4/8 w - - 0 1"]
[PlyCount "9"]
[EventDate "1999.??.??"]
[SourceVersionDate "2020.04.01"]
{[#]} 1. d3 $1 {as we shall see later, this move is essential to trap the
Black king} a3 (1... Kf4 2. e6+ {is a straightforward win}) 2. e6 dxe6 (2... a2
3. exd7 a1=Q 4. d8=Q {just leaves White material up and with no particular
difficulties in converting}) (2... Kxe6 {this line sets the theme for the
puzzle} 3. Kg6 {the Black king is now in a cage} a2 4. f4 a1=Q 5. f5#) 3. Be5
$1 {the hidden idea Christian was referring to.} Kxe5 (3... a2 4. Bxd4 $18) 4.
Kg5 {another cage for the Black king, repeating the theme established by the 2.
..Kxe6 line. Without the white pawn on d3 Black could play d3 himself and
escape.} a2 5. f4# *