Configuration Spaces of Graphs with Certain Permitted Collisions

If G is a graph with vertex set V, let Confnsink(G,V) be the space of n-tuples of points on G, which are only allowed to overlap on elements of V. We think of Confnsink(G,V) as a configuration space of points on G, where points are allowed to collide on vertices. In this paper, we attempt to understand these spaces from two separate, but closely related, perspectives. Using techniques of combinatorial topology we compute the fundamental groups and homology groups of Confnsink(G,V) in the case where G is a tree. Next, we use techniques of asymptotic algebra to prove statements about Confnsink(G,V), for general graphs G, whenever n is sufficiently large. It is proven that, for general graphs, the homology groups exhibit generalized representation stability in the sense of Ramos (arXiv:1606.02673, 2016).