23 citations · 56 across the 6 of their papers we have counts for
6 papers
Curves and envelopes that bound the spectrum of a matrix
Göran Bergqvist
A generalization of the method developed by Adam, Psarrakos and Tsatsomeros to find inequalities for the eigenvalues of a complex matrix A using knowledge of the largest eigenvalue…
Rank probabilities for real random tensors
G. Bergqvist, P. J. Forrester
We prove that the probability for a real random Gaussian tensor to be of real rank is , where , denote the gam…
The Chevreton Tensor and Einstein-Maxwell Spacetimes Conformal to Einstein Spaces
G. Bergqvist, I. Eriksson
In this paper we characterize the source-free Einstein-Maxwell spacetimes which have a trace-free Chevreton tensor. We show that this is equivalent to the Chevreton tensor being of…
Algebraic and differential Rainich conditions for symmetric trace-free tensors of higher rank
G. Bergqvist, P. Lankinen
We study Rainich-like conditions for symmetric and trace-free tensors T. For arbitrary even rank we find a necessary and sufficient differential condition for a tensor to satisfy t…
Unique characterization of the Bel-Robinson tensor
G. Bergqvist, P. Lankinen
We prove that a completely symmetric and trace-free rank-4 tensor is, up to sign, a Bel-Robinson type tensor, i.e., the superenergy tensor of a tensor with the same algebraic symme…
Algebraic Rainich theory and antisymmetrisation in higher dimensions
G. Bergqvist, A. Hoglund
The classical Rainich(-Misner-Wheeler) theory gives necessary and sufficient conditions on an energy-momentum tensor to be that of a Maxwell field (a 2-form) in four dimensions…