Abstract
•We construct symmetries and conservation laws of a fourth-order KdV–Klein/Gordon equation.•Study the fractional forms of the fourth-order KdV–Klein/Gordon equation.•Present travelling wave/soliton solutions and figures for the 1st case.
We study, using various approaches, the fourth-order KdV–Klein/Gordon PDE, viz., using the symmetry approach to reduction with some numerical method when the reduced version is no longer be solvable analytically. Then, we consider the fractional time evolution second-order Gordon type and fourth-order KdV–Klein/Gordon equations using the invariance approach when adapted to fractional PDEs. In the latter case, we show how conservation laws are constructed using the Lie symmetries. As usual, the conserved densities may be used to calculate conserved quantities.