You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
By item #2 we have $\text{cl}_X(U_i(\gamma)) = U_i(\gamma)\cup Z(i, \gamma)$. From this, $\text{cl}_Y(U_i(\gamma)) = (U_i(\gamma)\cup Z(i, \gamma))\cap Y = U_i(\gamma)$ so that $U_i(\gamma)$ is clopen in $Y$.
Suppose that $X$ is locally connected. Since $Y$ is open in $X$, if $\gamma\in Y$ then there is open connected $U$ with $\gamma\in U\subseteq Y$. There is $i$ such that $U_i(\gamma)\subseteq U$. Since $U_{i+1}(\gamma)$ is a proper subset of $U_i(\gamma)$, $U_{i+1}(\gamma)$ is a non-empty proper clopen subset of $U$. This contradicts that $U$ is connected.
The text was updated successfully, but these errors were encountered:
Trait Suggestion
The space Gustin's sequence space S122 is not Locally connected P41, but this fact is not known to pi-Base today:
link to pi-Base
Proof/References
Let$U_i(\alpha)$ be defined as in space #125 in DOI 10.1007/978-1-4612-6290-9_6.
By item #2 we have$\text{cl}_X(U_i(\gamma)) = U_i(\gamma)\cup Z(i, \gamma)$ . From this, $\text{cl}_Y(U_i(\gamma)) = (U_i(\gamma)\cup Z(i, \gamma))\cap Y = U_i(\gamma)$ so that $U_i(\gamma)$ is clopen in $Y$ .
Suppose that$X$ is locally connected. Since $Y$ is open in $X$ , if $\gamma\in Y$ then there is open connected $U$ with $\gamma\in U\subseteq Y$ . There is $i$ such that $U_i(\gamma)\subseteq U$ . Since $U_{i+1}(\gamma)$ is a proper subset of $U_i(\gamma)$ , $U_{i+1}(\gamma)$ is a non-empty proper clopen subset of $U$ . This contradicts that $U$ is connected.
The text was updated successfully, but these errors were encountered: