<p>We study Schauder bases for spaces of holomorphic functions in the open unit disk <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\mathbb {D}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">D</mi> </math></EquationSource> </InlineEquation>. Given a non-Blaschke sequence <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\((\lambda _n)_{n\ge 1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>λ</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>≥</mo> <mn>1</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> in <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mathbb {D}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">D</mi> </math></EquationSource> </InlineEquation>, we show that the associated sequence of finite Blaschke products <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\((B_n)_{n\ge 1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>B</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>≥</mo> <mn>1</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> forms a Schauder basis for <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\textrm{Hol}(\overline{\mathbb {D}})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>Hol</mtext> <mo stretchy="false">(</mo> <mover> <mi mathvariant="double-struck">D</mi> <mo>¯</mo> </mover> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> when this space is endowed with a norm inherited from a Banach space <i>X</i> satisfying a set of natural structural assumptions. This abstract framework includes, in particular, the classical Hardy spaces <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(H^p\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>H</mi> <mi>p</mi> </msup> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(1\le p\le \infty \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>≤</mo> <mi>p</mi> <mo>≤</mo> <mi>∞</mi> </mrow> </math></EquationSource> </InlineEquation>, the weighted Bergman spaces <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(A_\alpha ^p\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>A</mi> <mi>α</mi> <mi>p</mi> </msubsup> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(1\le p\le \infty \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>≤</mo> <mi>p</mi> <mo>≤</mo> <mi>∞</mi> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\alpha &gt;-1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>&gt;</mo> <mo>-</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, and BMOA. We further prove that if the sequence <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\((\lambda _n)_{n\ge 1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>λ</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>≥</mo> <mn>1</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> is contained in a compact subset of the open unit disk, then <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\((B_n)_{n\ge 1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>B</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>≥</mo> <mn>1</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> is a Schauder basis for <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\textrm{Hol}(\overline{\mathbb {D}})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>Hol</mtext> <mo stretchy="false">(</mo> <mover> <mi mathvariant="double-struck">D</mi> <mo>¯</mo> </mover> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> endowed with its natural topology. Moreover, in the case of Hardy spaces <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(H^p\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>H</mi> <mi>p</mi> </msup> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq15"> <EquationSource Format="TEX">\(1&lt;p&lt;\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>&lt;</mo> <mi>p</mi> <mo>&lt;</mo> <mi>∞</mi> </mrow> </math></EquationSource> </InlineEquation>, we provide a complete characterization of those sequences <InlineEquation ID="IEq16"> <EquationSource Format="TEX">\((\lambda _n)_{n\ge 1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>λ</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>≥</mo> <mn>1</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> for which the corresponding sequence of finite Blaschke products forms a Schauder basis. Finally, we discuss related phenomena in the context of the disk algebra <InlineEquation ID="IEq17"> <EquationSource Format="TEX">\(\mathcal {A}(\mathbb D)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">A</mi> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">D</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>.</p>

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Schauder Basis with Finite Blaschke Products

  • E. Fricain,
  • J. Mashreghi,
  • M. Nasri,
  • M. Ostermann

摘要

We study Schauder bases for spaces of holomorphic functions in the open unit disk \(\mathbb {D}\) D . Given a non-Blaschke sequence \((\lambda _n)_{n\ge 1}\) ( λ n ) n 1 in \(\mathbb {D}\) D , we show that the associated sequence of finite Blaschke products \((B_n)_{n\ge 1}\) ( B n ) n 1 forms a Schauder basis for \(\textrm{Hol}(\overline{\mathbb {D}})\) Hol ( D ¯ ) when this space is endowed with a norm inherited from a Banach space X satisfying a set of natural structural assumptions. This abstract framework includes, in particular, the classical Hardy spaces \(H^p\) H p , \(1\le p\le \infty \) 1 p , the weighted Bergman spaces \(A_\alpha ^p\) A α p , \(1\le p\le \infty \) 1 p , \(\alpha >-1\) α > - 1 , and BMOA. We further prove that if the sequence \((\lambda _n)_{n\ge 1}\) ( λ n ) n 1 is contained in a compact subset of the open unit disk, then \((B_n)_{n\ge 1}\) ( B n ) n 1 is a Schauder basis for \(\textrm{Hol}(\overline{\mathbb {D}})\) Hol ( D ¯ ) endowed with its natural topology. Moreover, in the case of Hardy spaces \(H^p\) H p , \(1<p<\infty \) 1 < p < , we provide a complete characterization of those sequences \((\lambda _n)_{n\ge 1}\) ( λ n ) n 1 for which the corresponding sequence of finite Blaschke products forms a Schauder basis. Finally, we discuss related phenomena in the context of the disk algebra \(\mathcal {A}(\mathbb D)\) A ( D ) .