<p>The metric geometric and spectral geometric means are two essential concepts in the theory of matrix mean. In [<CitationRef CitationID="CR15">15</CitationRef>], Lemos and Soares asked whether there exists the following log-majorization relation for <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(A, B\ge 0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>A</mi> <mo>,</mo> <mi>B</mi> <mo>≥</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(t\in [0,1]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>t</mi> <mo>∈</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation>, <Equation ID="Equ30"> <EquationSource Format="TEX">\(\begin{aligned} s(A^t(A\sharp _{t}B)B^{1-t}) {\mathop \prec \limits _{(\log )}} s(AB). \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <mi>s</mi> <mrow> <mo stretchy="false">(</mo> <msup> <mi>A</mi> <mi>t</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi>A</mi> <msub> <mo>♯</mo> <mi>t</mi> </msub> <mi>B</mi> <mo stretchy="false">)</mo> </mrow> <msup> <mi>B</mi> <mrow> <mn>1</mn> <mo>-</mo> <mi>t</mi> </mrow> </msup> <mo stretchy="false">)</mo> </mrow> <munder> <mo>≺</mo> <mrow> <mo stretchy="false">(</mo> <mo>log</mo> <mo stretchy="false">)</mo> </mrow> </munder> <mi>s</mi> <mrow> <mo stretchy="false">(</mo> <mi>A</mi> <mi>B</mi> <mo stretchy="false">)</mo> </mrow> <mo>.</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>Recently, Gan and Kim prove alternative versions of above log-majorization for the metric geometric and spectral geometric means in [<CitationRef CitationID="CR8">8</CitationRef>]. In this paper, by several Furuta-type inequalities, we obtain several log-majorizations of Lemos–Soares type for the metric geometric mean and weak log-majorizations of Lemos–Soares type for the spectral geometric mean, which extend the recent results from Gan and Kim and other related results.</p>

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Log-majorizations of Lemos–Soares type for the metric geometric and spectral geometric means

  • Jian Shi,
  • Zhaoyu Wang,
  • Cheng Wei

摘要

The metric geometric and spectral geometric means are two essential concepts in the theory of matrix mean. In [15], Lemos and Soares asked whether there exists the following log-majorization relation for \(A, B\ge 0\) A , B 0 , \(t\in [0,1]\) t [ 0 , 1 ] , \(\begin{aligned} s(A^t(A\sharp _{t}B)B^{1-t}) {\mathop \prec \limits _{(\log )}} s(AB). \end{aligned}\) s ( A t ( A t B ) B 1 - t ) ( log ) s ( A B ) . Recently, Gan and Kim prove alternative versions of above log-majorization for the metric geometric and spectral geometric means in [8]. In this paper, by several Furuta-type inequalities, we obtain several log-majorizations of Lemos–Soares type for the metric geometric mean and weak log-majorizations of Lemos–Soares type for the spectral geometric mean, which extend the recent results from Gan and Kim and other related results.