  We study functional clones, which are sets of non-negative pseudo-Boolean
functions (functions $\{0,1\}^k\to\mathbb{R}_{\geq 0}$) closed under
(essentially) multiplication, summation and limits. Functional clones naturally
form a lattice under set inclusion and are closely related to counting
Constraint Satisfaction Problems (CSPs). We identify a sublattice of
interesting functional clones and investigate the relationships and properties
of the functional clones in this sublattice.
