“…On the other hand, by dropping the nonconvex constraint rank.Z/ Ä d , one immediately obtains an SDP relaxation of the fixed-dimensional localization problem. Such a relaxation and its variants have been extensively studied in recent years (see, e.g., [3,4,7,9,10,12,16,19,21,22,24]) and are very natural as far as polynomial-time solvability is concerned. Moreover, they have the added advantage that in many cases, localization accuracy guarantees can be established; see, e.g., [10,[20][21][22]24].…”