There Is A Fine Line Between Severe And Overplay
A severe move puts pressure on the opponent by exploiting a specific defect of shape. It is the kind of move that only works because one has sufficient support. Here is a very simple example:
The invasion is justified here because it has support from both sides. It is severe because White's formation is too loose.
goes in too deeply. It seems severe to break up White's framework and to separate the marked stones, but as Black is lacking in support, White will retaliate with boshi at and Black will have a hard time living. was an overplay; a much milder move, such as an ear play at , was called for here.
If you can provide better examples, I will probably delete the above, as I did this in a hurry...Cheers.
Alex Weldon: This is also related to the idea of There are bad moves beside good moves?. Although it's often better to attack on a large scale, there are many times when playing fairly close (not in contact) with enemy stones is a very severe attack. But if you aren't strong enough all around, this can lead to amarigatachi, in which case the move was overplay. I'm not good enough to come up with an example on the fly. Anyone help me out here?