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 Beyond the cactus rank of tensors Bull. Korean Math. Soc. 2018 Vol. 55, No. 5, 1587-1598 https://doi.org/10.4134/BKMS.b170933Published online September 30, 2018 Edoardo Ballico University of Trento Abstract : We study additive decompositions (and generalized additive decompositions with a zero-dimensional scheme instead of a finite sum of rank $1$ tensors), which are not of minimal degree (for sums of rank $1$ tensors with more terms than the rank of the tensor, for a zero-dimensional scheme a degree higher than the cactus rank of the tensor). We prove their existence for all degrees higher than the rank of the tensor and, with strong assumptions, higher than the cactus rank of the tensor. Examples show that additional assumptions are needed to get the minimally spanning scheme of degree cactus $+1$. Keywords : tensor rank, tensor decomposition, cactus rank, zero-dimensional scheme, Segre embedding MSC numbers : 14N05, 15A69 Downloads: Full-text PDF