# Blocked migration to MathSE

The following MO question Why is $O(n;k)$ not connected, and has four connected components? (revisions/timeline)

• (a) has been closed as off-topic (by a set $A$ of 5 users)
• (b) was reopened (by a set $B$ of five users)
• (c) was closed (by a set $C$ of five users)
The sets $A,B,C$ can be found in the edit history; we have $A\cap (B\cup C)=\emptyset$, while $B\cap C$ has cardinal 3.