Puzzle 1 from an endgame textbook
The correct move is 1.C4-2
Red is in posession of the central file. If he can win
Black's pawn without losing control of the central file
he has a technically won endgame. In some positions he
might also try the typical method in this endgame
(see line B after 1.K5+1?) and try to win without capturing
the pawn. However, the pawn is already close to Red's palace
and Red has to be precise to achieve the win.
1.K5+1? allows 1. ... R8.4 Now Red cant try two plans,
but Black can defend the position successfully in both cases:
A) Red tries to capture Black's pawn
1.K5+1 R8.4 2.R5-1 R4-1 3.K5-1 P2+1 4.C4-1 (threatening C4.8)
4. ... R4-3 5.K5+1 P2+1 6.R5+3 (6.C4+7 R4+3 7.K5-1 P2.3 will
also yield a draw) 6. ... P2.3 7.C4+4 (planning 8.R5+4 9.C4.9
10.C9+4 11.C9.6 but Black won't allow that) 7. ... R4+3
8.K5+1 (8.K5-1 P3.4 9.K5.4 R4.8 and Red has lost the central
file) 8. ... R4+1 9.C4-4 (9.K5-1 R4-1 10.K5+1 is a legal
repetition of moves under Asian rules) 9.R4.5 C4.5 10.R5.4
and Red can't make any progress, Answer 1.
B) Red tries to adopt the typical plan in the endgame rook
ans cannon vs. rook without attacking Black's pawn
1.K5+1 R8.4 2.C4+1 (If Black idles in this position Red will
win, see e.g. 2. ... R4-4 3.R5+6 K4+1 4.C4.9 R4.1
5.R5-4 R1.4 6.C9+6 P2.3 7.R5+3 K4+1/K4-1 8.R5+1 K4-1/K4+1
9.C9.6 R4.7 10.R5-4 Answer 2) 2. ... P2.3 3.R5+6 K4+1
4.C4.9 P3+1 5.C9+6 P3.4 6.K5.4 (Red has lost control of the central
file and won't be able to regain it) 6. ... R4.1 7.C9.8 (7.K4+1 R1-2
.K4-1 R1+1) 7. ... R1-1 8.R5-3 P4.5 9.R5-5 R1.5 10.K4.5 draw, Answer 3
After 1.C4-2 Black has to play 1. ... R8-8 to avoid the immediate
checkmate 2.R5.6. In this line Red can win with exact play:
1.C4-2 R8-8 2.R5+6 K4+1 3.R5-7 R8+1 (3. ... P2.3 4.C4+2 and
Red can capture Black's pawn without losing control of the
central file) 4.C4+1! with these lines:
a) 4. ... R8.4 5.R5.8 R4.5 (or Red will play R8.5) 6.C4.5 R5.8
(6. ... R5.4 7.C5+1 is similiar) 7.C5+1 R8+6 8.R8+6 K4-1 9.R8.5
and Red wins, Answer 4
b) 4. ... R8+7 5.K5+1 R8-7 (5. ... R8.4 6.R5.8) 6.C4+1 P2+1
7.C4-1 P2+1 8.K5-1 R8.4 9.C4-1 R4.2 10.R5+1 P2.1 11.C4.9 R2+7
12.K5+1 and Red wins, Answer 5