The first well-known theoretical work on DNA denaturation by heating (without solvents) called the Poland-Scheraga model, discussed by C.Richard and A.Guttmann. According to the authors: "The question of the mechanisms applied to real DNA responsible for the denaturation process and which explain behavior as observed in melting curves is still far from being satisfactorily answered." The efforts toward improvement and further development or simplification of this model continue. Another rapidly developing direction of theoretical work toward understanding the denaturation process is the Nearest-Neighbor method, where the DNA helix is treated by the interaction between neighboring DNA/DNA base pairs. 36 I. Tinoco, O.Uhlenbeck, M.