  Using the symmetry group theory of second order PDEs, one finds the symmetry
group associated to Tzitzeica surfaces partial differential equation. One
studies the inverse problem and one shows that the Tzitzeica surfaces PDE is an
Euler-Lagrange equation. One determines the variational symmetry group of the
associated functional and one obtains the conservation laws of the Tzitzeica
surfaces PDE. All these results shows that the Tzitzeica surfaces theory is
strongly related to variational problems and hence it is a subject of global
differential geometry.
