Week 2: Rectangular Six in the Corner
I originally considered looking at one of the shapes related to the L-group for this week. The shapes listed under that link are slightly more complex descendants of the L-group, since analyzing them often makes use of what we’ve learned about the L-group (i.e., that it is dead).
However, before we move onto to those, I thought it might be worthwhile to look at another related shape (although it is more like a sibling to the L-group), the “Rectangular Six in the Corner”:
Sensei’s Library: https://senseis.xmp.net/?RectangularSixInTheCorner
Summary Notes:
- Life and death status depends on the number of liberties
- Zero liberties: unsettled, black lives by playing at a or b, white kills by playing at a
- One liberty: white can play at a to create an approach ko
- Two liberties: black is unconditionally alive
- Looks like an L-group, but with two descents closing off the corner space
Problems from Sensei’s Library: