Semi invariants for linear third order evolution equations

Abstract

We obtain equivalence transformations for linear third order evolution equations by exploiting Lie infinitesimal approach. Invariants for this class of equations are calculated using the derived set of equivalence transformations. We find second order invariants for the third order evolution equations under transformations of the dependent and independent variables, separately. Further, these quantities are used to reduce the linear third order evolution equations with variable coefficients to a simpler equation of the same family with constant coefficients.