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On Aleksandrov's obstruction theorem
I. A. Shvedov
Abstract:
The following two results ate proved.
Theorem 1. {\it Let $X$ be a subspace of a locally compact metric space with $\dim_{\mathscr G}X=p$, and $A$ the subset consisting of all points $a\in X$ such that $H^p(X,X\setminus U;\mathscr G)\ne 0$ for every sufficiently small open ball $U$ with centre at $a$. Then $\dim_{\mathscr G}A=p$}.
Theorem 2. {\it Let $X$ be a metric space, $\dim_{\mathscr G}X=p$, and $Y$ the subspace of $X$ consisting of all points $y\in X$ that have a basis of open neighbourhoods $\mathscr B(y)$ точки $y$ such that for each $U\in \mathscr B(y)$ the group $H^p(X,X\setminus U;\mathscr G)$ is not trivial. Then $\dim_{\mathscr G}Y=p$}.
Received: 01.03.1976
Citation:
I. A. Shvedov, “On Aleksandrov's obstruction theorem”, Russian Math. Surveys, 31:5 (1976), 192–197
Linking options:
https://www.mathnet.ru/eng/rm3967https://doi.org/10.1070/RM1976v031n05ABEH004196 https://www.mathnet.ru/eng/rm/v31/i5/p185
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