2959c81e_ufficient_Mating_Material_Rule__2
[0] Example H [2] 
This example shows another valid setup, where there are lot of forces, but mate is impossible. This position is not as blocked as the previous, since white has a free bishop. The problem is, that this bishop can't reach black's forces. Mate is impossible, so the game is drawn.
[E4EC] The insufficient Mating Material Rule
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