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Determinantal inequalities of Hua-Marcus-Zhang type for quaternion matrices

  • Yan Hong ORCID logo and Feng Qi ORCID logo EMAIL logo
Published/Copyright: July 9, 2021

Abstract

In this paper, the authors extend determinantal inequalities of the Hua-Marcus-Zhang type for positive definite matrices to the corresponding ones for quaternion matrices.

MSC 2010: 15B33; 11R52; 15A42; 15A45; 16H05; 20G20

1 Introduction and motivations

In 1955, Hua [1,2] established an elegant determinantal inequality as follows.

Theorem 1.1

[1,2, Theorems 1 and 2] Let A , B C n × n and A , B be conjugate matrices of A , B . If I n A A and I n B B are positive definite, then

(1.1) det ( I n A A ) det ( I n B B ) + det ( A B ) 2 det ( I n A B ) 2 ,

where I n denotes identity matrix of n order. In particular,

det ( I n A A ) det ( I n B B ) det ( I n A B ) 2 .

For A C n × n , we denote its eigenvalues and singular values by

λ 1 ( A ) , λ 2 ( A ) , , λ n ( A ) and σ 1 ( A ) , σ 2 ( A ) , , σ n ( A ) ,

respectively. If all eigenvalues of A C n × n are real, we assume

(1.2) λ 1 ( A ) λ 2 ( A ) λ n ( A ) ,

while we always write

(1.3) σ 1 ( A ) σ 2 ( A ) σ n ( A ) .

In 1958, Marcus [3] extended the determinantal inequality (1.1) to the following family of inequalities for eigenvalues of matrices.

Theorem 1.2

[3, Theorem] Let A , B C n × n . If I n A A and I n B B are positive definite, then inequality

(1.4) j = 1 k σ n j + 1 2 ( I n A B ) j = 1 k ( 1 λ j ( A A ) ) ( 1 λ j ( B B ) ) ,

is valid for 1 k n .

In 2011, Zhang [4] found a reversion of the determinantal inequality (1.1) below.

Theorem 1.3

[4, Theorem 7.18] If A , B C n × n , then

(1.5) det ( I n A B ) 2 det ( I n + A A ) det ( I n + B B ) det ( A + B ) 2 .

In the past few decades, many kinds of determinantal inequalities of the Hua-Marcus-Zhang type were presented in [3,4, 5,6,7, 8,9] and closely related references therein. In recent years, quaternions have been widely used in system control, signal and color image processing, geometric rotation, quantum mechanics, algebra, analysis, and other fields. For details, please refer to previous studies [10,11, 12,13,14, 15,16].

In this paper, we adopt notations for quaternion matrices in our own paper [17]. Hamilton [18] introduced the concept of real quaternions by

H = { x = a + b i + c j + d k : a , b , c , d R and i , j , k R } ,

where there exist the following operations:

i ¯ = i , j ¯ = j , k ¯ = k , i 2 = k 2 = j 2 = 1 , ij = ji = k , jk = kj = i , ki = ik = j .

Let H n × m be the set of n × m quaternion matrices and let H n be the set of self-conjugate n × n quaternion matrices. Xie [19,20, 21,22] studied a similarity standard form of the body matrices, the eigenvalue theory of centralizable matrices, and the determinant theory of self-conjugate quaternion matrices. Zhuang [23] established the Cauchy interleaving theorem of eigenvalues of self-conjugate quaternion matrices. Cao [24] investigated inequalities between eigenvalues and singular values of products of two quaternion matrices. The papers [17,25,26, 27,28,29, 30,31] are also related to the topic of this paper. The research of quaternion matrices has been being continuously active.

Definition 1.1

[32] Let A H n × n . If there exists λ H and x H n { 0 } such that

A x = λ x ( A x = x λ ) ,

then we say that λ and x are the left (right) eigenvalue and the corresponding left (right) eigenvector of A , respectively.

Since the quaternions do not commute, it is mandatory to treat the linear systems A x = λ x and A x = x λ separately. Rewrite the first one as ( λ I A ) x = 0 . In the complex case, the fact that det ( λ I A ) = 0 has a solution guarantees an eigenvalue for A . The existence of eigenvalue of a quaternion matrix is much more complicated, see [32]. It is known [33,34] that the right spectrum is always nonempty. In [35], Wood used a topological method to confirm that the left eigenvalue always exists.

Over a long period of time, there have been various kinds of definitions of determinant over the quaternion, see [19,22,36, 37,38]. Since eigenvalues of self-conjugate quaternion matrices are real numbers, see Lemma 2.1, we use the definition of determinants in [21,22] to investigate our problems in this paper.

In what follows, we assume that the eigenvalues λ j ( A ) of A H n and the singular values σ j ( A ) of A H n × n are expressed in the orders (1.2) and (1.3), respectively. In this paper, we will extend inequalities (1.1), (1.4), and (1.5) to the corresponding ones for quaternion matrices.

2 Lemmas

In order to extend inequalities (1.1), (1.4), and (1.5) to the corresponding ones for quaternion matrices, we need the following lemmas.

Lemma 2.1

[17, Proposition 2.1], [21, Theorem 13], and [22, Theorem 3] For A H n , there exists a generalized unitary matrix U H n × n (that is, U U = U U = I n ) such that

U A U = diag ( λ 1 ( A ) , λ 2 ( A ) , , λ n ( A ) ) .

Furthermore, if A is positive definite, then the least eigenvalue λ n ( A ) is positive.

Lemma 2.2

[17, Proposition 2.2] and [24, Theorems 2 and 3] Suppose A , B H n and B is positive definite. Then

  1. there exists a nonsingular matrix P = ( p 1 , p 2 , , p n ) H n × n such that

    P B P = I n and P A P = diag ( λ 1 ( A ) , λ 2 ( A ) , , λ n ( A ) ) ;

  2. the products A B and B A are both centralizable matrices and both of them are similar to a real diagonal matrix.

Lemma 2.3

Let A , B H n . If A , B are both positive semidefinite, then

(2.1) det ( A + B ) det ( A ) + det ( B ) .

Proof

When det B = 0 , inequality (2.1) holds trivially.

When det B 0 , by Lemma 2.2, there exists a nonsingular matrix P H n × n such that

P 1 ( A + B ) P = ( P P ) 1 ( D + I n ) ,

where D = diag ( λ 1 ( A + B ) , λ 2 ( A + B ) , , λ n ( A + B ) ) . Since

det ( A ) = [ det ( P P ) ] 1 det ( D ) , det ( B ) = [ det ( P P ) ] 1 , det ( D + I n ) det ( D ) + 1 ,

using Lemma 2.2, it follows that

det ( A + B ) = [ det ( P P ) ] 1 det ( D + I n ) det ( A ) + det ( B ) .

The proof of Lemma 2.3 is complete.□

Lemma 2.4

[23, Theorem 1] Let A H n be a matrix partitioned as

A = A k 1 A k 2 A k 3 A k 4 , A k 1 H k , 1 k n .

Then

λ ( A ) λ n k + ( A k 1 ) λ n k + ( A )

for 1 k , n . In particular, if A is positive semidefinite, then

(2.2) = 1 k λ ( A ) det ( A k 1 ) = 1 k λ n + 1 ( A )

for 1 k n .

Lemma 2.5

Let A , B H n × n . For 1 k n , we have

(2.3) = 1 k σ ( A ) σ ( B ) = 1 k σ ( A B ) = 1 k σ ( A ) σ n + 1 ( B )

(2.4) = 1 k σ n + 1 ( A B ) = 1 k σ n + 1 ( A ) σ n + 1 ( B ) .

Proof

The first inequality (2.3) in Lemma 2.5 comes from [39, Theorem 3].

We assume that A and B are nonsingular, otherwise we use the continuity of A A + ε I n and B B + ε I n in ε > 0 . By inequality (2.3), we obtain

= 1 k σ n + 1 ( A 1 ) σ ( B 1 ) = 1 k σ ( ( A B ) 1 ) = 1 k σ ( A 1 ) σ ( B 1 ) .

Since σ ( A 1 ) = σ n + 1 1 ( A ) for 1 n , we readily see that inequality (2.4) holds. The proof of Lemma 2.5 is complete.□

Lemma 2.6

Let A , B H n × n . Then

(2.5) I n + A A = ( A + B ) ( I n + B B ) 1 ( A + B ) + ( I n A B ) ( I n + B B ) 1 ( I n A B ) .

If I n A A and I n B B are nonsingular, then

(2.6) ( I n B A ) ( I n A A ) 1 ( I n A B ) = ( I n B B ) + ( A B ) ( I n A A ) 1 ( A B ) .

Proof

This follows from arguments similar to those corresponding ones in [4, p. 229] and [7, p. 124].□

3 Determinantal inequalities for quaternion matrices

We are now in a position to state and prove our main results which extend inequalities (1.1), (1.4), and (1.5) to the corresponding ones for quaternion matrices.

Theorem 3.1

Let A , B H n × n . If I n A A and I n B B are both positive definite, then

(3.1) j = 1 k σ n j + 1 2 ( I n A B ) j = 1 k [ 1 λ j ( A A ) ] [ 1 λ j ( B B ) ] + j = 1 k [ 1 λ j ( A A ) ] [ 1 λ n j + 1 ( A A ) ] 1 σ n j + 1 2 ( A B )

for 1 k n .

Proof

Since ( I n A B ) ( I n A B ) is positive semidefinite, by Lemma 2.1, there exists a generalized unitary matrix U = ( u 1 , u 2 , , u n ) H n × n such that

(3.2) U ( I n A B ) ( I n A B ) U = diag ( σ 1 2 ( I n A B ) , σ 2 2 ( I n A B ) , , σ n 2 ( I n A B ) ) .

Putting U k = ( u n k + 1 , , u n ) H n × k , by identity (2.6) in Lemma 2.6, we obtain

(3.3) U k ( I n B A ) ( I n A A ) 1 ( I n A B ) U k = U k ( I n B B ) U k + U k ( A B ) ( I n A A ) 1 ( A B ) U k .

Taking determinants on both sides of (3.3) and using Lemma 2.3, we acquire

det ( U k ( I n B A ) ( I n A A ) 1 ( I n A B ) U k ) = det ( U k ( I n B B ) U k + U k ( A B ) ( I n A A ) 1 ( A B ) U k ) det ( U k ( I n B B ) U k ) + det ( U k ( A B ) ( I n A A ) 1 ( A B ) U k ) .

Applying inequalities (2.2) and (2.4) yields

det ( U k ( I n B B ) U k ) j = 1 k λ n j + 1 ( I n B B ) = j = 1 k [ 1 λ j ( B B ) ]

and

det ( U k ( A B ) ( I n A A ) 1 ( A B ) U k ) j = 1 k σ n j + 1 2 ( ( A B ) ( I n A A ) 1 ( A B ) ) j = 1 k σ n j + 1 2 ( A B ) λ n j + 1 ( ( I n A A ) 1 ) = j = 1 k σ n j + 1 2 ( A B ) [ 1 λ n j + 1 ( A A ) ] 1 .

Using Lemma 2.4, inequality (2.3), and the matrix decomposition (3.2), we arrive at

det ( U k ( I n B A ) ( I n A A ) 1 ( I n A B ) U k ) = j = 1 k λ j ( U k ( I n B A ) ( I n A A ) 1 ( I n A B ) U k ) j = 1 k σ j 2 ( ( I n A B ) U k ) λ j ( ( I n A A ) 1 ) = j = 1 k σ n j + 1 2 ( I n A B ) [ 1 λ j ( A A ) ] 1 .

The proof of Theorem 3.1 is complete.□

Corollary 3.1

Let A , B H n × n . If I n A A and I n B B are both positive definite, then

j = 1 k σ n j + 1 2 ( I n A B ) j = 1 k [ 1 λ j ( A A ) ] [ 1 λ j ( B B ) ]

for 1 k n .

Proof

This follows from inequality (3.1) in Theorem 3.1.□

Corollary 3.2

Let A , B H n × n . If I n A A and I n B B are both positive definite, then

det ( I n A A ) det ( I n B B ) + det ( A B ) 2 det ( I n A B ) 2 .

In particular,

det ( I n A A ) det ( I n B B ) det ( I n A B ) 2 .

Proof

This follows from letting k = n in Theorem 3.1.□

Theorem 3.2

Let A , B H n × n . For 1 k n , we have

j = 1 k σ n j + 1 2 ( I n A B ) + j = 1 k σ n j + 1 2 ( A + B ) j = 1 k [ 1 + λ n j + 1 ( A A ) ] [ 1 + λ j ( B B ) ] .

Proof

There exists a generalized unitary matrix U = ( u 1 , u 2 , , u n ) H n × n such that

U ( I n + A A ) U = diag ( λ 1 ( I n + A A ) , λ 2 ( I n + A A ) , , λ n ( I n + A A ) ) .

Taking U k = ( u n k + 1 , , u n ) H n × k , utilizing the matrix identity (2.5) in Lemma 2.6, and employing inequalities in Lemmas 2.3 and 2.4 lead to

j = 1 k [ 1 + λ n j + 1 ( A A ) ] = det ( U k ( I n + A A ) U k ) det ( U k ( A + B ) ( I n + B B ) 1 ( A + B ) U k ) + det ( U k ( I n A B ) ( I n + B B ) 1 ( I n A B ) U k ) j = 1 k σ n j + 1 2 ( A + B ) [ 1 + λ j ( B B ) ] 1 + j = 1 k σ n j + 1 2 ( I n A B ) [ 1 + λ j ( B B ) ] 1 .

The proof of Theorem 3.2 is thus complete.□

Corollary 3.3

Let A , B H n × n . Then

det ( I n A B ) 2 det ( I n + A A ) det ( I n + B B ) det ( A + B ) 2 .

Proof

This follows from setting k = n in Theorem 3.2.□


https://qifeng618.wordpress.com

# Dedicated to Professor Jen-Chih Yao at China Medical University in Taiwan.


Acknowledgements

The authors appreciate anonymous referees for their careful corrections to and valuable comments on the original version of this paper.

  1. Funding information: This work was supported in part by the Natural Science Foundation of Inner Mongolia (Grant No. 2019MS01007), by the Science Research Fund of Inner Mongolia University for Nationalities (Grant No. NMDBY15019), and by the Research Program of Science and Technology at Universities of Inner Mongolia Autonomous Region (Grant No. NJZY19157 and No. NJZY20119) in China.

  2. Author contributions: All authors contributed equally to the manuscript and read and approved the final manuscript.

  3. Conflict of interest: Authors state no conflict of interest.

  4. Data availability statement: Data sharing is not applicable to this article as no new data were created or analyzed in this study.

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Received: 2021-02-09
Revised: 2021-05-17
Accepted: 2021-06-21
Published Online: 2021-07-09

© 2021 Yan Hong and Feng Qi, published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

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  59. A note on polyexponential and unipoly Bernoulli polynomials of the second kind
  60. On the type 2 poly-Bernoulli polynomials associated with umbral calculus
  61. Some estimates for commutators of Littlewood-Paley g-functions
  62. Construction of a family of non-stationary combined ternary subdivision schemes reproducing exponential polynomials
  63. On the evolutionary bifurcation curves for the one-dimensional prescribed mean curvature equation with logistic type
  64. On intersections of two non-incident subgroups of finite p-groups
  65. Global existence and boundedness in a two-species chemotaxis system with nonlinear diffusion
  66. Finite groups with 4p2q elements of maximal order
  67. Positive solutions of a discrete nonlinear third-order three-point eigenvalue problem with sign-changing Green's function
  68. Power moments of automorphic L-functions related to Maass forms for SL3(ℤ)
  69. Entire solutions for several general quadratic trinomial differential difference equations
  70. Strong consistency of regression function estimator with martingale difference errors
  71. Fractional Hermite-Hadamard-type inequalities for interval-valued co-ordinated convex functions
  72. Montgomery identity and Ostrowski-type inequalities via quantum calculus
  73. Universal inequalities of the poly-drifting Laplacian on smooth metric measure spaces
  74. On reducible non-Weierstrass semigroups
  75. so-metrizable spaces and images of metric spaces
  76. Some new parameterized inequalities for co-ordinated convex functions involving generalized fractional integrals
  77. The concept of cone b-Banach space and fixed point theorems
  78. Complete consistency for the estimator of nonparametric regression model based on m-END errors
  79. A posteriori error estimates based on superconvergence of FEM for fractional evolution equations
  80. Solution of integral equations via coupled fixed point theorems in 𝔉-complete metric spaces
  81. Symmetric pairs and pseudosymmetry of Θ-Yetter-Drinfeld categories for Hom-Hopf algebras
  82. A new characterization of the automorphism groups of Mathieu groups
  83. The role of w-tilting modules in relative Gorenstein (co)homology
  84. Primitive and decomposable elements in homology of ΩΣℂP
  85. The G-sequence shadowing property and G-equicontinuity of the inverse limit spaces under group action
  86. Classification of f-biharmonic submanifolds in Lorentz space forms
  87. Some new results on the weaving of K-g-frames in Hilbert spaces
  88. Matrix representation of a cross product and related curl-based differential operators in all space dimensions
  89. Global optimization and applications to a variational inequality problem
  90. Functional equations related to higher derivations in semiprime rings
  91. A partial order on transformation semigroups with restricted range that preserve double direction equivalence
  92. On multi-step methods for singular fractional q-integro-differential equations
  93. Compact perturbations of operators with property (t)
  94. Entire solutions for several complex partial differential-difference equations of Fermat type in ℂ2
  95. Random attractors for stochastic plate equations with memory in unbounded domains
  96. On the convergence of two-step modulus-based matrix splitting iteration method
  97. On the separation method in stochastic reconstruction problem
  98. Robust estimation for partial functional linear regression models based on FPCA and weighted composite quantile regression
  99. Structure of coincidence isometry groups
  100. Sharp function estimates and boundedness for Toeplitz-type operators associated with general fractional integral operators
  101. Oscillatory hyper-Hilbert transform on Wiener amalgam spaces
  102. Euler-type sums involving multiple harmonic sums and binomial coefficients
  103. Poly-falling factorial sequences and poly-rising factorial sequences
  104. Geometric approximations to transition densities of Jump-type Markov processes
  105. Multiple solutions for a quasilinear Choquard equation with critical nonlinearity
  106. Bifurcations and exact traveling wave solutions for the regularized Schamel equation
  107. Almost factorizable weakly type B semigroups
  108. The finite spectrum of Sturm-Liouville problems with n transmission conditions and quadratic eigenparameter-dependent boundary conditions
  109. Ground state sign-changing solutions for a class of quasilinear Schrödinger equations
  110. Epi-quasi normality
  111. Derivative and higher-order Cauchy integral formula of matrix functions
  112. Commutators of multilinear strongly singular integrals on nonhomogeneous metric measure spaces
  113. Solutions to a multi-phase model of sea ice growth
  114. Existence and simulation of positive solutions for m-point fractional differential equations with derivative terms
  115. Bernstein-Walsh type inequalities for derivatives of algebraic polynomials in quasidisks
  116. Review Article
  117. Semiprimeness of semigroup algebras
  118. Special Issue on Problems, Methods and Applications of Nonlinear Analysis (Part II)
  119. Third-order differential equations with three-point boundary conditions
  120. Fractional calculus, zeta functions and Shannon entropy
  121. Uniqueness of positive solutions for boundary value problems associated with indefinite ϕ-Laplacian-type equations
  122. Synchronization of Caputo fractional neural networks with bounded time variable delays
  123. On quasilinear elliptic problems with finite or infinite potential wells
  124. Deterministic and random approximation by the combination of algebraic polynomials and trigonometric polynomials
  125. On a fractional Schrödinger-Poisson system with strong singularity
  126. Parabolic inequalities in Orlicz spaces with data in L1
  127. Special Issue on Evolution Equations, Theory and Applications (Part II)
  128. Impulsive Caputo-Fabrizio fractional differential equations in b-metric spaces
  129. Existence of a solution of Hilfer fractional hybrid problems via new Krasnoselskii-type fixed point theorems
  130. On a nonlinear system of Riemann-Liouville fractional differential equations with semi-coupled integro-multipoint boundary conditions
  131. Blow-up results of the positive solution for a class of degenerate parabolic equations
  132. Long time decay for 3D Navier-Stokes equations in Fourier-Lei-Lin spaces
  133. On the extinction problem for a p-Laplacian equation with a nonlinear gradient source
  134. General decay rate for a viscoelastic wave equation with distributed delay and Balakrishnan-Taylor damping
  135. On hyponormality on a weighted annulus
  136. Exponential stability of Timoshenko system in thermoelasticity of second sound with a memory and distributed delay term
  137. Convergence results on Picard-Krasnoselskii hybrid iterative process in CAT(0) spaces
  138. Special Issue on Boundary Value Problems and their Applications on Biosciences and Engineering (Part I)
  139. Marangoni convection in layers of water-based nanofluids under the effect of rotation
  140. A transient analysis to the M(τ)/M(τ)/k queue with time-dependent parameters
  141. Existence of random attractors and the upper semicontinuity for small random perturbations of 2D Navier-Stokes equations with linear damping
  142. Degenerate binomial and Poisson random variables associated with degenerate Lah-Bell polynomials
  143. Special Issue on Fractional Problems with Variable-Order or Variable Exponents (Part I)
  144. On the mixed fractional quantum and Hadamard derivatives for impulsive boundary value problems
  145. The Lp dual Minkowski problem about 0 < p < 1 and q > 0
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