25. When a Cannon is attacking an unprotected Knight, Guard, Minister,
or Pawn that has crossed the river, it will be a perpetual chase even
if only the cannon mount moves but neither the attacking Cannon
nor the attacked piece moves.
However, perpetually chasing a Pawn that has NOT crossed the river
is allowed. (See examples in Diagram 56 to 60)
Diagram 56: Red (in Capital) moves first
P12 c58
P23 c87
P32 c78
P23 c85
P32 ...
Explanation:
The Black Knight is not protected and cannot be perpetually chased.
The Red Cannon uses different mounts to attack the Black knight and
is perpetually chasing the Black Knight. Red has to change.
Diagram 57: Red (in Capital) moves first
C34 c96
g4-5 c68
g5+4 c96
G4-5 c68
G5+5 c86
G4-5 c68
G5+4 ...
.
.
Diagram 58: Red (in Capital) moves first
C43 c76
M1+3 c67
M3-1 c78
M5+3 c87
M3-5 ...
Explanation:
In Diagrams 57 and 58, the Red Cannon keeps chasing the Black Guard
or Minister by changing its mounts. Red violates the rule and has
to change.
Diagram 59: Red (in Capital) moves first
M3+1 c79
M1+3 c96
M3-1 c69
M1+3 c96
M3-1 ...
Explanation:
The Red Cannon perpetually chases the Black Pawn by changing
its mounts. Because the Black Pawn has crossed the river, Red
violates the rule and has to change.
Diagram 60: Red (in Capital) moves first
M3+1 c79
M1+3 c96
M3-1 c69
M1+3 c96
M3-1 ...
Explanation:
Although Red perpetually chases the Black Pawn, which is unprotected,
by changing its mounts, because the Black Pawn has not crossed the river
this does not violate the rule and the game should be ruled a draw.