On Uniqueness of the $n$th Order Tensor Decomposition into Rank-1 Terms with Linear Independence in One Mode

  • Authors:
  • Alwin Stegeman

  • Affiliations:
  • a.w.stegeman@rug.nl

  • Venue:
  • SIAM Journal on Matrix Analysis and Applications
  • Year:
  • 2010

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Abstract

We study uniqueness of the decomposition of an $n$th order tensor (also called $n$-way array) into a sum of $R$ rank-1 terms (where each term is the outer product of $n$ vectors). This decomposition is also known as Parafac or Candecomp, and a general uniqueness condition for $n=3$ has been obtained by Kruskal in 1977 [Linear Algebra Appl., 18 (1977), pp. 95-138]. More recently, Kruskal's uniqueness condition has been generalized to $n\geq3$, and less restrictive uniqueness conditions have been obtained for the case where the vectors of the rank-1 terms are linearly independent in (at least) one of the $n$ modes. For this case, only $n=3$ and $n=4$ have been studied. We generalize these results by providing a framework of analysis for arbitrary $n\geq3$. Our results include necessary, sufficient, necessary and sufficient, and generic uniqueness conditions. For the sufficient uniqueness conditions, the rank of a matrix needs to be checked. The generic uniqueness conditions have the form of a bound on $R$ in terms of the dimensions of the tensor to be decomposed.