© 1980 by London Mathematical Society
Kamke's Uniqueness Theorem
Department of Mathematics, University of Auckland Auckland, New Zealand
A generalization of Kamke's uniqueness theorem in ordinary differential equations is obtained for the limit Cauchy problem, viz x'(t) = f(t, x(t)), x{t)
x0 as t t0, where f and x take values in an arbitrary normed linear space X and the initial point (t0, x0) is permitted to be on the boundary of the domain of f. Kamke's hypothesis that ||f(t,x) f(t,y)||
ø(|tto|, ||x,y||) is replaced by a weaker dissipative-type hypothesis formulated in terms of the duality map of X and a semi-inner product derived from it. Even in the scalar case in which X = R, the generalization obtained is still an extension of Kamke's theorem and some of its later analogues.