Unusual three-stone enclosures
Based on the 4-4 point:
The 3-3 invasion here is a famous reading problem. See 364463 enclosure and 364463Enclosure33Invasion.
The most common way for White to invade here is at a.
See BQM 21 / Lower Right for the 3-3 invasion. Its own page at 364473 enclosure.
This doesn't seem well co-ordinated as far as taking the corner is concerned, but is seen in pro games.
If pros now make these enclosures, against traditional teaching, there could be several reasons:
- try for extra territory, despite worse aji;
- play a move more distant from the corner as a more effective checking extension;
- invite an invasion for useful thickness.
Benjamin:I think that pros rather make this shape if they already played two of the moves and the third one serves well in the global context, for example as tsume.
As part of the 'Korean style' (also seen in players such as O Meien), the use of this enclosure is probably more often because of reasons 1 and 2.
The 3554 enclosure is also a source of several unusual three-stone enclosures.
See also: pillbox, 355563 enclosure, 464464 enclosure, super pillbox, Three Crows, unusual enclosures, 364464 enclosure 3-3 invasion.