Configuration X
- ⟨en-1, en, en+1⟩.
- 3 consecutive edges that make up X.
- P
- The Polygon formed by X.
Configurations are important for the simplifying step in the algorithm.
Contraction
- R+(X)
- Positive contraction region.
- R-(X)
- Negative contraction region.
A contraction is an edge-move that causes one of the edges of X to reach length zero.