Noga Alon Dan Halperin Oren Nechushtan Micha Sharir The complexity of the outer face in arrangements of random segments. 69-78 2008 Symposium on Computational Geometry http://doi.acm.org/10.1145/1377676.1377689 conf/compgeom/2008 db/conf/compgeom/compgeom2008.html#AlonHNS08