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One example of general unidentifiable tensors. (English) Zbl 1346.14125

Summary: The identifiability of parameters in a probabilistic model is a crucial notion in statistical inference. We prove that a general tensor of rank \(8\) in \(\mathbb{C}^3\otimes\mathbb{C}^6\otimes\mathbb{C}^6\) has at least \(6\) decompositions as sum of simple tensors, so it is not \(8\)-identifiable. This is the highest known example of balanced tensors of dimension \(3\), which are not \(k\)-identifiable, when \(k\) is smaller than the generic rank.

MSC:

14N05 Projective techniques in algebraic geometry
15A69 Multilinear algebra, tensor calculus
62F10 Point estimation