부산대학교 도서관

In this work, we present a new approach to find non-local symmetries and contact symmetries from the admitted Lie point symmetries of the considered system of nonlinear differential equations. By introducing a new function in both the numerator and denominator in the relation which relates the λ -symmetry function and the Lie point symmetry characteristics, we generate non-local symmetries as well as contact symmetries. To do so, we have to define another function g 3 and then we identify two different cases, where the function g 3 = 0 and g 3 ≠ 0 . To validate the results, we consider the Ricatti chain as an example and find the non-local and contact symmetries admitted by the first four of the underlying equations. We also find the contact symmetries admitted by the well-known Mathews–Lakshmanan oscillator equation. [ABSTRACT FROM AUTHOR]