<p>How reasonable is the conjecture that <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\ell _\infty /C[0,1]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>ℓ</mi> <mi>∞</mi> </msub> <mo stretchy="false">/</mo> <mi>C</mi> <mrow> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">]</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> separably injective? Formulated in homological terms this amounts to asking whether <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\operatorname {Ext}^2(S, C[0,1])=0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mo>Ext</mo> <mn>2</mn> </msup> <mrow> <mo stretchy="false">(</mo> <mi>S</mi> <mo>,</mo> <mi>C</mi> <mrow> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">]</mo> </mrow> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation> for every separable space. We wheel around this question and obtain new connections between <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\operatorname {Ext}^2\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mo>Ext</mo> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>-results and classical Banach space theorems of Johnson–Zippin, Kalton and Lindenstrauss–Pełczyński.</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

All \(\mathcal L_\infty \)-spaces are separably injective, kind of

  • Jesús M. F. Castillo,
  • Yolanda Moreno

摘要

How reasonable is the conjecture that \(\ell _\infty /C[0,1]\) / C [ 0 , 1 ] separably injective? Formulated in homological terms this amounts to asking whether \(\operatorname {Ext}^2(S, C[0,1])=0\) Ext 2 ( S , C [ 0 , 1 ] ) = 0 for every separable space. We wheel around this question and obtain new connections between \(\operatorname {Ext}^2\) Ext 2 -results and classical Banach space theorems of Johnson–Zippin, Kalton and Lindenstrauss–Pełczyński.