Line Percolation in Finite Projective Planes
  We study combinatorial parameters of a recently introduced bootstrap percolation problem in finite projective planes. We present sharp results on the size of the minimum percolating sets and the maximal non-percolating sets. Additional results on the minimal and maximal percolation time as well as on the critical probability in the projective plane are also presented. 
D\'aniel Gerbner, Bal\'azs Keszegh, G\'abor M\'esz\'aros, Bal\'azs   Patk\'os, M\'at\'e Vizer
math.CO