@unpublished{ HosseiniLukeUschmajew:2017, author = {Hosseini, Seyedehsomayeh and Luke, D. Russell and Uschmajew, Andr\'e}, title = {Tangent and normal cones for low-rank matrices}, year = {2017}, month = {oct}, annote = {preprint}, pdf = {http://neitzel.ins.uni-bonn.de/research/pub/hosseini/LowRankCones.pdf} , note = {INS Preprint No. 1715}, inspreprintnum= {1715} }