On a topological problem arising in physics
J. P. J. Lafon · Journal of Mathematical Physics · 1977
The investigation of a large class of problems in physics requires the determination of the ranges of some parameters ξ, E, ⋅⋅⋅ for which equations of the form F (r; ξ, E,⋅⋅⋅) =0 have some or no roots in a given bounded or unbounded interval of r. The solution of this problem is given under the form of three general theorems. Examples of utilization in physics are also discussed.