  The evaluation of partition functions is a central problem in statistical
physics. For lattice systems and other discrete models the partition function
may be expressed as the contraction of a tensor network. Unfortunately
computing such contractions is difficult, and many methods to make this
tractable require periodic or otherwise structured networks. Here I present a
new algorithm for contracting unstructured tensor networks. This method makes
no assumptions about the structure of the network and performs well in both
structured and unstructured cases so long as the correlation structure is
local.
