A technique is described, involving integration by parts, for constructing Liapunov functions for a class of third- and fourth-order differential equations. The procedure makes use of a number of "differential moments"
![M_{n} = \\int\\min{t_{0}}\\max {t} (d^{n}x/dt^{n})L[x]dt](/images/tex/4422.gif)
, where
![L[x] = 0](/images/tex/4423.gif)
is the differential equation under consideration. The moment equations

are manipulated to obtain a single expression
![[V(x,dot{x},\\ddot{x},... )]\\min{t_{0}}\\max {t} = \\int\\min{t_{0}}\\max {t} k(x,dot{x},\\ddot{x}...)dt](/images/tex/4425.gif)
. Conditions are applied to the functions involved in
![L[x]](/images/tex/4426.gif)
so as to make

positive definite and

negative semidefinite, in which case

will be a Liapunov function for
![L[x]=0](/images/tex/4428.gif)
.