<p>It is well known that for every measurable function <i>a</i>, essentially bounded on the positive halfline, the corresponding radial Toeplitz operator <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(T_a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation>, acting in the Segal–Bargmann–Fock space, is diagonal with respect to the canonical orthonormal basis consisting of normalized monomials. We denote by <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\gamma _a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>γ</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation> the corresponding eigenvalues sequence. Given an arbitrary convergent sequence, we uniformly approximate it by sequences of the form <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\gamma _a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>γ</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation> with any desired precision. We give a simple recipe for constructing <i>a</i> in terms of Laguerre polynomials. Previously, we proved this approximation result with non-constructive tools (Esmeral and Maximenko in Complex Anal. Oper. Theory 10, 2016). In the present paper, we also include some properties of the sequences <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\gamma _a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>γ</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation> and some properties of bounded sequences, uniformly continuous with respect to the sqrt-distance on natural numbers.</p>

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Constructive approximation of convergent sequences by eigenvalue sequences of radial Toeplitz–Fock operators

  • Kevin Esmeral García,
  • Egor A. Maximenko

摘要

It is well known that for every measurable function a, essentially bounded on the positive halfline, the corresponding radial Toeplitz operator \(T_a\) T a , acting in the Segal–Bargmann–Fock space, is diagonal with respect to the canonical orthonormal basis consisting of normalized monomials. We denote by \(\gamma _a\) γ a the corresponding eigenvalues sequence. Given an arbitrary convergent sequence, we uniformly approximate it by sequences of the form \(\gamma _a\) γ a with any desired precision. We give a simple recipe for constructing a in terms of Laguerre polynomials. Previously, we proved this approximation result with non-constructive tools (Esmeral and Maximenko in Complex Anal. Oper. Theory 10, 2016). In the present paper, we also include some properties of the sequences \(\gamma _a\) γ a and some properties of bounded sequences, uniformly continuous with respect to the sqrt-distance on natural numbers.