Nonlinear Limit-Point Type Solutions of nth Order Differential Equations

We continue the study of limit-pointrlimit-circle type differential equations of the nth order. In particular, we show that the differential expression y 4 k.qry, ks1, 2, . . . , is never of the limit-circle type as long as r is not an unbounded oscillatory function; this partially answers an open question and generalizes our result for ns4. This follows as a consequence of new results on the nonlinear limit-pointrlimit-circle problem for the equation y n.sr t.f y, y9, . . . , y ny1...