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Are quasicomponents connected in a compact space?

Background:

So this question is about whether the first result can be generalized to non-Hausdorff spaces.

kaba
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1 Answers1

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The following counter-example is taken from A. Tarizadeh, Idempotents and connected components, Example 3.15 (but I'm pretty sure that it appeared elsewhere long before):

Define $Y = \{\frac{1}{n}: n \in \mathbb N\} \cup \{0\}$ as a subspace of $\mathbb R$ and define $X = Y \cup \{0^*\}$ by doubling $0$, i.e. X is the subspace of the line with two origins.

Obviously, $Y$ is compact, $T_1$. Moreover, every clopen set, which contains $0$, also contains $0^*$. As each $\{\frac{1}{n}: n \ge m\} \cup \{0, 0^* \}$ is clopen, the quasi-component of $0$ is $\{0, 0^* \}$. However, $\{0, 0^* \}$ is discrete, hence not connected.

Ulli
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