  The action dimension of a discrete group G, actdim(G), is defined to be the
smallest integer m such that G admits a properly discontinuous action on a
contractible m-manifold. If no such m exists, we define actdim(G) = infty.
Bestvina, Kapovich, and Kleiner used Van Kampen's theory of embedding
obstruction to provide a lower bound to the action dimension of a group. In
this article, another lower bound to the action dimension of a group is
obtained by extending their work, and the action dimensions of the fundamental
groups of certain manifolds are found by computing this new lower bound.
