Kerodon

$\Newextarrow{\xRightarrow}{5,5}{0x21D2}$ $\newcommand\empty{}$
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$

Proposition 4.8.7.14. Let $F: \operatorname{\mathcal{C}}\rightarrow \operatorname{\mathcal{D}}$ be an isofibration of $\infty $-categories and let $n$ be an integer. The following conditions are equivalent:

$(1)$

The functor $F$ is categorically $n$-connective.

$(2)$

For every integer $0 \leq m \leq n$, every lifting problem

\[ \xymatrix@C =50pt@R=50pt{ \operatorname{\partial \Delta }^{m} \ar [r] \ar [d] & \operatorname{\mathcal{C}}\ar [d]^{F} \\ \Delta ^{m} \ar@ {-->}[ur] \ar [r] & \operatorname{\mathcal{D}}} \]

admits a solution.

$(3)$

For every simplicial set $B$ of dimension $\leq n$ and every simplicial subset $A \subseteq B$, every lifting problem

\[ \xymatrix@C =50pt@R=50pt{ A \ar [r] \ar [d] & \operatorname{\mathcal{C}}\ar [d]^{F} \\ B\ar@ {-->}[ur] \ar [r] & \operatorname{\mathcal{D}}} \]

admits a solution.

Proof. The equivalence $(1) \Leftrightarrow (2)$ follows from Proposition 4.8.5.30. The implication $(3) \Rightarrow (2)$ is immediate, and the reverse implication follows from Proposition 1.1.4.12. $\square$