The fundamental groupoid as a terminal costack

Abstract

Let $X$ be a topological space. We denote by ${\pi }_0(X)$ the set of connected components of $X$ and by ${\Pi }_1(U)$ the fundamental groupoid. In this paper we prove that for good topological spaces the assignments $U\mapsto {\pi }_0(U)$ and $U\mapsto {\Pi }_1(U)$ are the terminal cosheaf and costack respectively.