The nonequivalence of oscillation and nondisconjugacy

G. B. Gustafson
1970 Proceedings of the American Mathematical Society  
A sufficient condition is given for all solutions of the adjoint of an Mth order linear differential equation to have an infinity of zeros; an example is presented which shows that for every integer n>2, there exists an nth order equation, all of whose solutions have a finite number of zeros, but the adjoint has only solutions with an infinity of zeros. In addition, some open equations on conjugate points are answered.
doi:10.1090/s0002-9939-1970-0284648-4 fatcat:msfb3hhnyfevralpleamlukvbq