Convergence of the state error e to zero in adaptive systems is shown
using the existence and uniqueness of solution and the existence of a
Lyapunov function in which the adaptation laws are constructed. Result
s in the paper are general in the sense that it is applicable to a bro
ad class of adaptive systems of a linear/nonlinear, time-varying or di
stributed-parameter systems. Since the approach taken in the paper doe
s not require the boundedness of the derivative of the state error e f
or all t greater than or equal to 0, it is particularly useful in the
adaptive control of infinite dimensional systems.