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arXiv 0905.1396math.AT
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有理自同伦等价与Whitehead exact sequence

Rational self-homotopy equivalences and Whitehead exact sequence

Mahmoud Benkhalifa

摘要:

对于单连通CW-复$X$,令$\mathcal{E}(X)$表示$X$的自同伦等价的同伦类的群,令$\mathcal{E}_{\sharp}(X)$表示它的诱导同伦群上的恒等式的同伦类的子群.正如我们所知,商群$\frac{\mathcal{E}(X)}{\mathcal{E}_{\sharp}(X)}$可以用$Aut(π_{*}(X))$的子群来标识。这项工作的目的是确定这个子群的合理空间。我们构造了与$X$的最小Sullivan模型相关联的Whitehead正合序列,它允许我们定义分次向量空间$\mathrm{Hom}(π_*(X),\Bbb Q)$的自相干自同构的子群$\mathrm{Coh.Aut}(\mathrm{Hom}\big(π_{*}(X),\Bbb Q)\big)$.因此,我们建立了$\mathcal{E}(X) / \mathcal{E}_{\sharp}(X) \cong \mathrm{Coh.Aut} (\mathrm{Hom}(π_*(X),\Bbb Q))$。此外,通过计算群$\mathrm{Coh.Aut}\big(\mathrm{Hom}(π_{*}(X),\Bbb Q)\big)$,我们给出了具有少量自同伦等价的有理空间的例子。

英文摘要:

For a simply connected CW-complex $X$, let $\mathcal{E}(X)$ denote the group of homotopy classes of self-homotopy equivalence of $X$ and let $\mathcal{E}_{\sharp}(X)$ be its subgroup of homotopy classes which induce the identity on homotopy groups. As we know, the quotient group $\frac{\mathcal{E}(X)}{\mathcal{E}_{\sharp}(X)}$ can be identified with a subgroup of $Aut(π_{*}(X))$. The aim of this work is to determine this subgroup for rational spaces. We construct the Whitehead exact sequence associated with the minimal Sullivan model of $X$ which allows us to define the subgroup $\mathrm{Coh.Aut}(\mathrm{Hom}\big(π_{*}(X),\Bbb Q)\big)$ of self-coherent automorphisms of the graded vector space $\mathrm{Hom}(π_*(X),\Bbb Q)$. As a consequence we establish that $\mathcal{E}(X) / \mathcal{E}_{\sharp}(X) \cong \mathrm{Coh.Aut} (\mathrm{Hom}(π_*(X),\Bbb Q))$. In addition, by computing the group $\mathrm{Coh.Aut}\big(\mathrm{Hom}(π_{*}(X),\Bbb Q)\big)$, we give examples of rational spaces that have few self-homotopy equivalences.

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