  In a recent paper E. Formenti and K. Perrot (FP) introduce a global rule
assumed to describe the discrete time dynamics associated with a sandpile model
under the parallel application of a suitable local rule acting on d dimensional
lattices of cells equipped with uniform neighborhood. In this paper we submit
this approach to a critical analysis, in the simplest elementary particular
case of a one-dimensional lattice, which can be divided in two parts. In the
first part we prove that the FP global rule does not describe the dynamics of
standard sandpiles, but rather furnishes a description of the quite different
situation of height difference between consecutive piles. This is a semantic
uncorrect difference of interpretation. In the second part we investigate the
consequences of the uncorrect FP assumption proving that their global rule
describes a bidirectional spurious dynamics of icepiles (rather than
sandpiles), in the sense that this latter is the consequence of application of
three local rules: bidirectional vertical rule, bidirectional horizontal rule
(typical of icepiles), and a granule jump from the bottom to the top (spurious
rule of the dynamics).
