<p>For a fixed unital Banach <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(*\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mrow /> <mo>∗</mo> </mrow> </math></EquationSource> </InlineEquation>-probability space <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\left( A,\tau \right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <mi>A</mi> <mo>,</mo> <mi>τ</mi> </mfenced> </math></EquationSource> </InlineEquation>, we construct a definite, or indefinite inner product space <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\left( A_{0},\left[ ,\right] _{\tau }\right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mfenced close="]" open="["> <mo>,</mo> </mfenced> <mi>τ</mi> </msub> </mfenced> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(A_{0}=A/ker\left( \tau \right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>=</mo> <mi>A</mi> <mo stretchy="false">/</mo> <mi>k</mi> <mi>e</mi> <mi>r</mi> <mfenced close=")" open="("> <mi>τ</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation> is the quotient Banach space and <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\left[ ,\right] _{\tau }\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mfenced close="]" open="["> <mo>,</mo> </mfenced> <mi>τ</mi> </msub> </math></EquationSource> </InlineEquation> is a definite, or indefinite inner product on <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(A_{0}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>A</mi> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation> determined by the trace <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\tau \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>τ</mi> </math></EquationSource> </InlineEquation> on the unital Banach <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(*\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mrow /> <mo>∗</mo> </mrow> </math></EquationSource> </InlineEquation>-algebra <i>A</i>. From this Banach space <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\left( A_{0},\left[ ,\right] _{\tau }\right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mfenced close="]" open="["> <mo>,</mo> </mfenced> <mi>τ</mi> </msub> </mfenced> </math></EquationSource> </InlineEquation>, a functional vector space, called the <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(A_{0}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>A</mi> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation>-Hardy space <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\textbf{H}_{A_{0}:2}\left( D_{1}\right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="bold">H</mi> <mrow> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>:</mo> <mn>2</mn> </mrow> </msub> <mfenced close=")" open="("> <msub> <mi>D</mi> <mn>1</mn> </msub> </mfenced> </mrow> </math></EquationSource> </InlineEquation>, is constructed, where <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(D_{1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mn>1</mn> </msub> </math></EquationSource> </InlineEquation> is the open unit ball of <InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(A_{0}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>A</mi> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation>. Similar to the classical Toeplitz-operator theory, one can define Toeplitz-like adjointable Banach-space operators acting on <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\(\textbf{H}_{A_{0}:2}\left( D_{1}\right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="bold">H</mi> <mrow> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>:</mo> <mn>2</mn> </mrow> </msub> <mfenced close=")" open="("> <msub> <mi>D</mi> <mn>1</mn> </msub> </mfenced> </mrow> </math></EquationSource> </InlineEquation>. Our main results characterizes operator-theoretic properties of those Toeplitz-like operators over <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(\left( A,\tau \right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <mi>A</mi> <mo>,</mo> <mi>τ</mi> </mfenced> </math></EquationSource> </InlineEquation>. In particular, self-adjointness, projection-property, normality, isometry-property, and unitarity are characterized as in the usual operator theory on Hilbert spaces. As application, we study free distributions of certain types of our operator-valued Toeplitz-like operators.</p>

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Block-Toeplitz Operators On the Hardy Space Induced by a Tracial Unital Banach \(*\)-Probability Space

  • Ilwoo Cho,
  • Palle E. T. Jorgensen

摘要

For a fixed unital Banach \(*\) -probability space \(\left( A,\tau \right) \) A , τ , we construct a definite, or indefinite inner product space \(\left( A_{0},\left[ ,\right] _{\tau }\right) \) A 0 , , τ , where \(A_{0}=A/ker\left( \tau \right) \) A 0 = A / k e r τ is the quotient Banach space and \(\left[ ,\right] _{\tau }\) , τ is a definite, or indefinite inner product on \(A_{0}\) A 0 determined by the trace \(\tau \) τ on the unital Banach \(*\) -algebra A. From this Banach space \(\left( A_{0},\left[ ,\right] _{\tau }\right) \) A 0 , , τ , a functional vector space, called the \(A_{0}\) A 0 -Hardy space \(\textbf{H}_{A_{0}:2}\left( D_{1}\right) \) H A 0 : 2 D 1 , is constructed, where \(D_{1}\) D 1 is the open unit ball of \(A_{0}\) A 0 . Similar to the classical Toeplitz-operator theory, one can define Toeplitz-like adjointable Banach-space operators acting on \(\textbf{H}_{A_{0}:2}\left( D_{1}\right) \) H A 0 : 2 D 1 . Our main results characterizes operator-theoretic properties of those Toeplitz-like operators over \(\left( A,\tau \right) \) A , τ . In particular, self-adjointness, projection-property, normality, isometry-property, and unitarity are characterized as in the usual operator theory on Hilbert spaces. As application, we study free distributions of certain types of our operator-valued Toeplitz-like operators.