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Consider $\omega+1$ with the interval topology, that is $U\subseteq (\omega+1)$ is open if and only if $U\subseteq\omega$ or $(\omega+1)\setminus U$ is finite.

We write $(\omega+1)^\omega$ for the collection of all functions $f:\omega\to(\omega+1)$. Let $\Box (\omega+1)^\omega$ be the set $(\omega+1)^\omega$ endowed with the box topology, where each factor $(\omega+1)$ carries the interval topology.

For each $f\in(\omega+1)^\omega$ we consider the following clopen neighborhood $U_f$ of $f$:

$U_f = \{g\in(\omega+1)^\omega:\forall n\in\omega\big((f(n) < \omega \Rightarrow g(n) = f(n)) \text{ and } (f(n) = \omega \Rightarrow g(n) \in [n,\omega])\big) \}$

Let ${\cal U} = \{U_f: f\in(\omega+1)^\omega\}$. Is there an open covering ${\cal V}$ of $(\omega+1)^\omega$ with the following properties?

  • each member of ${\cal V}$ is contained in some member of ${\cal U}$;
  • for $V\neq W \in {\cal V}$ we have $V\cap W = \emptyset$.

Note: This is one special case of this question, see Joel David Hamkins' comment below.

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  • $\begingroup$ See the OP's earlier unanswered related question: mathoverflow.net/q/194281/1946. $\endgroup$ Commented May 11, 2015 at 12:11
  • $\begingroup$ @JoelDavidHamkins I am asking now for a very particular case of the question you are referring to. Thanks for linking to that question, I will include it in this post. $\endgroup$ Commented May 11, 2015 at 12:14
  • $\begingroup$ Dominic, although it is a special case, it isn't clear to me that it is any easier than the general case. $\endgroup$ Commented May 11, 2015 at 12:17
  • $\begingroup$ Maybe a special case that is more treatable is if I replace $[n,\omega]$ by $[1,\omega]$ in the definition of $U_f$ (or... if that is trivial, $[2, \omega$]). $\endgroup$ Commented May 11, 2015 at 12:19
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    $\begingroup$ Can you not just take the $U_f$'s for $f$ such that if $f(n)<\omega$, then $f(n)<n$? $\endgroup$ Commented May 11, 2015 at 12:25

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