Conjecture on the only generically identifiable perfect tensor formats

Let a tensor have format (n1,,nd)(n_1,\dots,n_d), and let

R(n1,,nd)=ini1+i(ni1).R(n_1,\dots,n_d)=\frac{\prod_i n_i}{1+\sum_i(n_i-1)}.

Call the format perfect when R(n1,,nd)R(n_1,\dots,n_d) is an integer, and call a format generically identifiable when a general tensor of that format has a unique decomposition as a sum of R(n1,,nd)R(n_1,\dots,n_d) decomposable tensors. The perfect-format identifiability conjecture. The only perfect formats for which a general tensor has a unique decomposition are (2,k,k)(2,k,k) for some kk, (3,4,5)(3,4,5), and (2,2,2,3)(2,2,2,3). The formats (2,k,k)(2,k,k) are the classically known matrix-pencil cases, identified by Kronecker normal form. The conjecture proposes a complete list of perfect generically identifiable formats, extending the two newly established cases beyond the classical matrix-pencil family; its resolution concerns the uniqueness of tensor decompositions in the balanced perfect-rank setting.

Sources & referencesView supporting material

Primary source

Jonathan D. Hauenstein, Luke Oeding, Giorgio Ottaviani and Andrew J. Sommese, “Homotopy techniques for tensor decomposition and perfect identifiability”, arXiv:1501.00090 (2016).

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