Forcing subarrangements in complete arrangements of pseudocircles

@article{Ortner2015ForcingSI,
  title={Forcing subarrangements in complete arrangements of pseudocircles},
  author={Ronald Ortner},
  journal={JoCG},
  year={2015},
  volume={6},
  pages={235-248}
}
In arrangements of pseudocircles (i.e., Jordan curves) the weight of a vertex (i.e., an intersection point) is the number of pseudocircles that contain the vertex in its interior. We show that in complete arrangements (in which each two pseudocircles intersect) 2n−1 vertices of weight 0 force an α-subarrangement, a certain arrangement of three pseudocircles… CONTINUE READING