general commonly involves forcing the general out of his original position with check or with threats. Thus, specific points and formations are very important in xiangqi. For an attacking (Red) horse, the most fatal points are c9 and g9 (Chinese: 臥槽馬), especially since without proper defence a quick mate can follow with an extra chariot or cannon. For a cannon, one of the most fatal formations is the exposed cannon (Chinese: 空心炮), where the cannon directly controls the middle file with no other pieces between the cannon and the general. This formation is particularly dangerous since the defensive side cannot move any piece in front of the cannon; while with an extra cannon joining the attack, mate can follow on the spot, and with an extra rook, the defensive side can mount a double check (with the rook in front of the cannon) followed by a windmill, often winning at least a piece afterwards. If the defensive side cannot chase the cannon away or capture it, it must move the general forward to avoid these threats, leaving the general vulnerable to attacks. Another fatal formation, called the "cannon-controlled centroid horse" (Chinese: 炮鎮窩心馬, diagram at right), also requires particularly bad coordination of the enemy pieces. In the diagram, Black's "centroid horse" occupies the centre of the palace, blocking Black's own general and advisors, and being pinned to the general by the red cannon, cannot move. Black's cannon at e8 is also pinned to its own general; it too is unable to move and restricts the movement of Black's two elephants, making them unable to protect each other. Such a formation in the middlegame often produces deadly threats of smothered mates, while in the endgame, as in the diagram, Red's cannon cannot be chased away, rendering Black's general, advisors, cannon on e8, and horse all permanently unable to move. Even though Black is up a minor piece, Red has a clear win: The game concluded 41.Hg7 (forking the elephant and pinned cannon and creating a mating threat) Eg10 42.Hh9 Ci9 43.Hf8+ Cf9 (if not for the other black cannon, it is instant mate) 44.Hxg6, and Black resigned: Black's only active piece (the cannon on f9) is absolutely helpless to stop Red's horse and soldiers, which will soon invade the palace. A common defensive configuration is to leave the general at its starting position, deploy one advisor and one elephant on the two