This study of the effect of variable change on differential operators was motivated by recent
papers of Tipler [131 and Hinton and Lewis [37] which appeared in the same issue of the …

1. Introduction. Let P (x) be an m× m matrix-valued function that is continuous, real,
symmetric, and positive definite for all x in an interval J, which will be further specified. Let w …

An open question which was asked by IM Glazman is answered. It is well known that the
condition\[\lim\limits _ {x\to\infty}{x^{2n-1}}\int _x^\infty {{r^{-1}}= 0}\] is sufficient for the …

Let ℋ be a Hilbert space, let ℬ=(ℋ, ℋ) be the B*-algebra of bounded linear operators from ℋ
to ℋ with the uniform operator topology, and let ℒ be the subset of ℬ consisting of the self …

The function q is continuous. The operator A is called oscillatory (oscillatory at zero) if for
each positive number a there exist positive numbers b and c with a< b< c (a> b> c) such that …

This paper presents sufficient conditions on the coefficents of ${L_ {2n}} y=\Sigma _ {k= 0}^ n
{(-1)^{nk}}{({p_k}{y^{(nk)}})^{(nk)}} $ which insure that ${L_ {2n}} y= 0$ has conjugate points …

The system of equations\[\sum\limits _ {k= 0}^ n {{{(-1)}^{nk}}{{\left ({{P_k}(x){y^{(nk)}}(x)}\right
)}^{(nk)}}}= 0\quad (0\leqslant x<\infty)\] is considered where the coefficients are real …

Define the self-adjoint operatorwhere r (x)> 0 on (0,∞) and q and p are real-valued. The
coefficient q is assumed to be differentiate on (0,∞) and r is assumed to be twice differentia …

Commentationes Mathematicae Universitatis Carolinae Page 1 Commentationes Mathematicae
Universitatis Carolinae Ondřej Došlý; Frank Fiedler A remark on Nehari-type oscillation criteria …

We consider the self-adjoint differential equation (a*(x) u”)”-(a,(x) u')'+ so (x) u= 0, O< x< a,
a< co,(1) a2 EC*, a, E C', a, EC, az (x)> 0, 0< x< a, a,(x) real-valued, i= 0, 1, 2, and are …