Complete prolongation for infinitesimal automorphisms on almost complex manifolds

We study the almost complex manifold and its symmetry algebra, the set of germs of infinitesimal automorphisms. The main result is that there is a certain condition to a torsion bundle under which the dimension of the symmetry algebra can not exceed 4 in the case of complex dimension 2. We will give an example which attains the maximal dimension 4, and another example without non-degeneracy whose symmetry algebra is of infinite dimension.