  We review some existing methods for the computation of first order moments on
junction trees using Shafer-Shenoy algorithm. First, we consider the problem of
first order moments computation as vertices problem in junction trees. In this
way, the problem is solved using the memory space of an order of the junction
tree edge-set cardinality. After that, we consider two algorithms,
Lauritzen-Nilsson algorithm, and Mau\'a et al. algorithm, which computes the
first order moments as the normalization problem in junction tree, using the
memory space of an order of the junction tree leaf-set cardinality.
