2959c81e_ufficient_Mating_Material_Rule__2
[0] Example B [2] 
This position is also drawn, white can't mate black and black can't mate white. If black's king were in a corner white couldn't control all four squares in that corner with his king and his one bishop, so mate is impossible. Therefore the game is immediately drawn when a position like this occurs.
[E4EC] The insufficient Mating Material Rule
2