OSCILLATION CRITERIA FOR 2ND-ORDER LINEAR-DIFFERENTIAL EQUATIONS

Some oscillation criteria are given for the second order linear differential equation [r(t)u'(t)]' + c(t)u(t) = 0, where r(t) is an element of C-1([t(0), infinity); (0, infinity)) and c(t) is an element of C([t(0), infinity); R). These results improve oscillation criteria of Wintner, Hartman, Kamenev, Yan, and Philos by using a generalized Riccati transformation v(t) = a(t)r(t){u'(t)lu(t) + f(t)}, where f is an element of C-1 is a given function on [t(0), infinity) and a(t) = exp{-2 integral(l) f(s) ds}. (C) 1995 Academic Press, Inc.