Definition (1), found in [CG, 6.1.4]. We call $F$ a factorization algebra if for each Weiss cover $\mathcal{U}$ of an open set $U\subset M$, the map $$ T\to FU $$ is a quasi-isomorphism, where $T$ denotes the totalization of the normalized chain complex in $\cal C$ (regarded as a cochain complex in $\cal C$ concentrated in negative degrees) associated with the simplicial object $\{\bigoplus_{U_{0},\dots,U_{n}\in\mathcal{U},\ U_i \mathrm{all\ distinct}}F\left(U_{0}\cap\cdots\cap U_{n}\right)\}_{n\geq0}$$\{\bigoplus_{U_{0},\dots,U_{n}\in\mathcal{U}}F\left(U_{0}\cap\cdots\cap U_{n}\right)\}_{n\geq0}$.
make Definition 1 closer to [CG] by adding "all distinct", Weiss cover of U in Definition 3
Became Hot Network Question