<p>This paper investigates a fundamental problem in frame theory: characterizing frames of the form <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq1.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="72" /> </InlineMediaObject> <EquationSource Format="TEX">\(\{T^k \varphi \}_{k=0}^\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mo stretchy="false">{</mo> <msup> <mi>T</mi> <mi>k</mi> </msup> <mi>φ</mi> <mo stretchy="false">}</mo> </mrow> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>∞</mi> </msubsup> </math></EquationSource> </InlineEquation>, where <i>T</i> is a bounded linear operator on a Hilbert space <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {H}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">H</mi> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq6.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="52" /> </InlineMediaObject> <EquationSource Format="TEX">\(\varphi \in \mathcal {H}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>φ</mi> <mo>∈</mo> <mi mathvariant="script">H</mi> </mrow> </math></EquationSource> </InlineEquation>. Our primary goal is to identify conditions under which such an iterative sequence forms a frame for <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {H}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">H</mi> </math></EquationSource> </InlineEquation>. In particular, we provide a complete characterization of diagonal operators on <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq8.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="39" /> </InlineMediaObject> <EquationSource Format="TEX">\(\ell ^2(\mathbb {N})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>ℓ</mi> <mn>2</mn> </msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">N</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> that generate frames of this form. Additionally, we establish necessary conditions for a frame <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq9.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="57" /> </InlineMediaObject> <EquationSource Format="TEX">\(\{f_k\}_{k=0}^\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mo stretchy="false">{</mo> <msub> <mi>f</mi> <mi>k</mi> </msub> <mo stretchy="false">}</mo> </mrow> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>∞</mi> </msubsup> </math></EquationSource> </InlineEquation> to admit a representation as <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1839_Article_IEq10.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="75" /> </InlineMediaObject> <EquationSource Format="TEX">\(\{T^k f_1\}_{k=0}^\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mo stretchy="false">{</mo> <msup> <mi>T</mi> <mi>k</mi> </msup> <msub> <mi>f</mi> <mn>1</mn> </msub> <mo stretchy="false">}</mo> </mrow> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>∞</mi> </msubsup> </math></EquationSource> </InlineEquation>. Further related results are also presented.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

On Frames of the Form \(\{T^k \varphi \}_{k=0}^\infty \): Conditions and Characterizations

  • Jahangir Cheshmavar

摘要

This paper investigates a fundamental problem in frame theory: characterizing frames of the form \(\{T^k \varphi \}_{k=0}^\infty \) { T k φ } k = 0 , where T is a bounded linear operator on a Hilbert space \(\mathcal {H}\) H and \(\varphi \in \mathcal {H}\) φ H . Our primary goal is to identify conditions under which such an iterative sequence forms a frame for \(\mathcal {H}\) H . In particular, we provide a complete characterization of diagonal operators on \(\ell ^2(\mathbb {N})\) 2 ( N ) that generate frames of this form. Additionally, we establish necessary conditions for a frame \(\{f_k\}_{k=0}^\infty \) { f k } k = 0 to admit a representation as \(\{T^k f_1\}_{k=0}^\infty \) { T k f 1 } k = 0 . Further related results are also presented.