-porosity is separably determined
We prove a separable reduction theorem for -porosity of Suslin sets. In particular, if is a Suslin subset in a Banach space , then each separable subspace of can be enlarged to a separable subspace such that is -porous in if and only if is -porous in . Such a result is proved for several types of -porosity. The proof is done using the method of elementary submodels, hence the results can be combined with other separable reduction theorems. As an application we extend a theorem...