Amos Beimel Boaz Ben-Moshe Yehuda Ben-Shimol Paz Carmi Eldad Chai Itzik Kitroser Eran Omri Matrix columns allocation problems. 2174-2183 2009 410 Theor. Comput. Sci. 21-23 http://dx.doi.org/10.1016/j.tcs.2009.02.015 db/journals/tcs/tcs410.html#BeimelBBCCKO09