Article
Keywords:
eventual disconjugacy
Summary:
The work characterizes when is the equation $ y^{ (n) } + \mu p(x) y = 0 $ eventually disconjugate for every value of $ \mu $ and gives an explicit necessary and sufficient integral criterion for it. For suitable integers $ q $, the eventually disconjugate (and disfocal) equation has 2-dimensional subspaces of solutions $ y $ such that $ y^{ (i) } > 0 $, $ i = 0, \ldots , q-1 $, $ (-1)^{i-q} y^{ (i) } > 0 $, $ i = q, \ldots , n $. We characterize the “smallest” of such solutions and conjecture the shape of the “largest” one. Examples demonstrate that the estimates are sharp.
References:
[Ea] Eastham, M. S. P.:
The asymptotic solution of linear differential systems. University Press, Oxford, 1989.
MR 1006434 |
Zbl 0674.34045
[E1] Elias, U.:
Oscillation theory of two-term differential equations. Kluwer Academic Publishers, Dordrecht, 1997.
MR 1445292 |
Zbl 0878.34022
[E2] Elias, U.:
Comparison theorems for disfocality and disconjugacy of differential equations. SIAM J. Math. Anal. 15 (1984), 922–931.
MR 0755852 |
Zbl 0554.34021
[KC] Kiguradze, I. T., and Chanturia, T. A.:
Asymptotic properties of solutions of nonautonomous ordinary differential equations. Kluwer Academic Publishers, Dordrecht, 1993.
MR 1220223
[Ki] Kim, W. J.:
Asymptotic properties of nonoscillatory solutions of higher order differential equations. Pacific J. Math. 93 (1981), 107–114.
MR 0621601 |
Zbl 0488.34046
[PSz] Pólya, G., and Szegö, G.: Problems and theorems in analysis. Springer-Verlag, Berlin, 1972.