Free, not recursively free and non rigid arrangements
arXiv:1406.6154
Abstract
We construct counterexamples to Yoshinaga's conjecture that every free arrangement is either inductively free or rigid in characteristic zero. The smallest example has $13$ hyperplanes, its intersection lattice has a one dimensional moduli space, and it is free but not recursively free.
After posting the first version of this paper, I was informed by Professor Takuro Abe that Abe, Kawanoue, and Nozawa also found the arrangement with 13 hyperplanes independently, see arXiv:1406.5820. 9 pages, 2 figures