dilevin
commented
4 years ago I’d have to check more closely.
These diagrams are taken from the textbook which does occasionally have some errors (nobody’s perfect).
That being said... we don’t use these data structures in the course and they won’t appear on tests without lots of explanation so don’t worry about the details. As long as you understand the basic idea you will be fine.
On the left figure, should the labels not be flipped for rprev and rnext? We are moving in a counter clockwise direction for each face that is left and right of this edge. So when we look at the left face lnext and lprev are correctly labelled because lnext is the first edge in the counter clockwise direction. However, on the right face the edge labelled rprev should be rnext as that is the first edge in the CCW direction.
The figure on the right looks to be correct. For example on edge c the left successor is a and left predecessor is b and right successor is d and right predecessor is e. I looked at a couple of these edges and they all look to be correct. So there's a mismatch between these two figures and I think the left one is incorrect.