1,240 research outputs found
Positive Definiteness and Semi-Definiteness of Even Order Symmetric Cauchy Tensors
Motivated by symmetric Cauchy matrices, we define symmetric Cauchy tensors
and their generating vectors in this paper. Hilbert tensors are symmetric
Cauchy tensors. An even order symmetric Cauchy tensor is positive semi-definite
if and only if its generating vector is positive. An even order symmetric
Cauchy tensor is positive definite if and only if its generating vector has
positive and mutually distinct entries. This extends Fiedler's result for
symmetric Cauchy matrices to symmetric Cauchy tensors. Then, it is proven that
the positive semi-definiteness character of an even order symmetric Cauchy
tensor can be equivalently checked by the monotone increasing property of a
homogeneous polynomial related to the Cauchy tensor. The homogeneous polynomial
is strictly monotone increasing in the nonnegative orthant of the Euclidean
space when the even order symmetric Cauchy tensor is positive definite.
Furthermore, we prove that the Hadamard product of two positive semi-definite
(positive definite respectively) symmetric Cauchy tensors is a positive
semi-definite (positive definite respectively) tensor, which can be generalized
to the Hadamard product of finitely many positive semi-definite (positive
definite respectively) symmetric Cauchy tensors. At last, bounds of the largest
H-eigenvalue of a positive semi-definite symmetric Cauchy tensor are given and
several spectral properties on Z-eigenvalues of odd order symmetric Cauchy
tensors are shown. Further questions on Cauchy tensors are raised
Centrosymmetric, Skew Centrosymmetric and Centrosymmetric Cauchy Tensors
Recently, Zhao and Yang introduced centrosymmetric tensors. In this paper, we
further introduce skew centrosymmetric tensors and centrosymmetric Cauchy
tensors, and discuss properties of these three classes of structured tensors.
Some sufficient and necessary conditions for a tensor to be centrosymmetric or
skew centrosymmetric are given. We show that, a general tensor can always be
expressed as the sum of a centrosymmetric tensor and a skew centrosymmetric
tensor. Some sufficient and necessary conditions for a Cauchy tensor to be
centrosymmetric or skew centrosymmetric are also given. Spectral properties on
H-eigenvalues and H-eigenvectors of centrosymmetric, skew centrosymmetric and
centrosymmetric Cauchy tensors are discussed. Some further questions on these
tensors are raised
Complex Network Analysis of Highway Network in Guangdong Province in China
In this paper, complex network theory is introduced to analyze the highway network in Guangdong Province (GDHN), the topology structure of GDHN was presented using the L space methodology. Then the network properties, such as degree distribution, closeness centrality, betweenness centrality, have been applied to analyze the statistical features of the GDHN. The results shows that the hubs supporting the communication of different highways are mostly located in the Pearl River Delta area. The highway development levels between different regions are very unbalanced. At last, some suggestions about the future construction of GDHN are proposed
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