Example 5.81.
Since \((S^0\to *) \ssquare u = \nabla(u)\), we see that \(u \in \EffEpi \backslash \Iso\) if and only if \(u\) is an epimorphism. More generally, we inductively get
\[\Cotr_{n+1} = \EffEpi \backslash \Cotr_n.\]
Higher Topos Theory Section 5.6: Products of acyclic classes
Example 5.81.
Since \((S^0\to *) \ssquare u = \nabla(u)\), we see that \(u \in \EffEpi \backslash \Iso\) if and only if \(u\) is an epimorphism. More generally, we inductively get