A form invariance and a conserved quantity of the generalised Birkhoffian system are studied.First,a definition and a criterion of the form invariance are given.Secondly,through the form invariance,a new conserved quantity can be deduced.Finally,an example is given to illustrate the application of the result.
Stability for the manifolds of equilibrium states of a generalized Birkhoff system is studied.A theorem for the stability of the manifolds of equilibrium states of the general autonomous system is used to the generalized Birkhoffian system and two propositions on the stability of the manifolds of equilibrium states of the system are obtained.An example is given to illustrate the application of the results.
