Maxime Crochemore Costas S. Iliopoulos Marcin Kubica Jakub Radoszewski Wojciech Rytter Tomasz Walen On the maximal number of highly periodic runs in a string http://arxiv.org/abs/0907.2157 2009 CoRR abs/0907.2157 db/journals/corr/corr0907.html#abs-0907-2157 informal publication