2959c81e_ufficient_Mating_Material_Rule__2
[0] Example D [2] 
This position is also drawn, since white can't control four squares in the corner (or six squares at an edge), so can't mate black. And of course, black can't mate white. If white had one more knight, the position would not be drawn, because mate is possible with two knights. That is known, mate can't be forced with two knights, but if black plays bad enough, or takes suicide moves (like helpmate) the mate is possible. So a king and two knights against king position is not drawn based on the insufficient material rule.
[E4EC] The insufficient Mating Material Rule
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