Locally (co)Cartesian fibrations as realisation fibrations and the classifying space of cospans

Abstract

We show that the conditions in Steimle's ‘additivity theorem for cobordism categories’ can be weakened to only require locally (co)Cartesian fibrations, making it applicable to a larger class of functors. As an application we compute the difference in classifying spaces between the infinity category of cospans of finite sets and its homotopy category.