K. Mcleod, UNIQUENESS OF POSITIVE RADIAL SOLUTIONS OF DELTA-U+F(U)=0 IN R(N) .2., Transactions of the American Mathematical Society, 339(2), 1993, pp. 495-505
We prove a uniqueness result for the positive solution of DELTAu + f(u
) = 0 in R(n) which goes to 0 at infinity. The result applies to a wid
e class of nonlinear functions f, including the important model case f
(u) = - u + u(p), 1 < p < (n + 2)/(n - 2). The result is proved by red
ucing to an initial-boundary problem for the ODE u'' + (n - 1)/r + f(u
) = 0 and using a shooting method.