Upper and lower limits for the number of S-wave bound states in an attractive potential

New upper and lower limits are given for the number of S-wave bound states yielded by an attractive (monotonic) potential in the context of the Schrodinger or Klein-Gordon equation.Comment: 21 pages, 4 figures, to appear in J. Math. Phy

On the connection between real and complex interpolation of quasi-Banach spaces

We describe a new approach to interpolate by the complex method quasi-Banach couples formed by real-intermediate spaces. End-point cases are also considered, and applications are given to function spaces and to operator spaces