“…This construction, which is termed the "polymer expansion" or "cluster expansion", is an important tool in mathematical statistical mechanics [97,29,47,31,24], and much effort has been devoted to finding complex polydiscs in which the polymer expansion is convergent, i.e. in which the (polymer-)lattice-gas partition function is nonvanishing [88,33,97,29,72,30,32,100,37,38,89,90,31,82,25,101,102,104]. One goal of this paper is to make a modest contribution to this line of development.…”