A. Abdesselam and V. Rivasseau
Trees, forests and jungles:
a botanical garden for cluster expansions
(89K, TeX)

ABSTRACT.  Combinatoric formulas for cluster expansions have been improved
many times over the years. Here we develop some new combinatoric
proofs and extensions of the tree formulas of Brydges
and Kennedy, and test them on a series of pedagogical examples.