“…The most important features of these rigorous results are: for α > 2, the system shows only a disordered phase, ∀T [1,2]; for 1 < α ≤ 2, there is a phase transition at finite temperature T c [3,4]; critical mean field behavior occurs for 1 < α ≤ 1.5 [1,2]; for α < 1, only one ordered phase exists, ∀T . Regarding the evaluation of approximate results, both renormalization group schemes [5]- [8] and numerical calculations of finite size systems [7]- [10] have been used to estimate the thermodynamical properties, the critical temperature and the critical exponents when 1 < α ≤ 2.…”