12 citations · 38 across the 23 of their papers we have counts for
26 papers
A New Characterization of the Domains of Integral Powers of the Self-Adjoint Friedrichs-Legendre Operator
Lance Littlejohn, Richard Wellman, Quinn Wicks
Let be the self-adjoint operator in , generated by the second-order classical Legendre differential equation% \[ \ell\lbrack y](t)=-\left( (1-t^{2})y^{\prime}(t)\r…
Carl Størmer and his Numbers
Matthew Kroesche, Lance L. Littlejohn, Graeme Reinhart
In many proofs of Fermat's Two Squares Theorem, the smallest least residue solution of the quadratic congruence plays an essential role; here is p…
Abstract Left-Definite Theory: A Model Operator Approach, Examples, Fractional Sobolev Spaces, and Interpolation Theory
Christoph Fischbacher, Fritz Gesztesy, Paul Hagelstein +1
We use a model operator approach and the spectral theorem for self-adjoint operators in a Hilbert space to derive the basic results of abstract left-definite theory in a straightfo…
The Jacobi operator on and its various -functions
Fritz Gesztesy, Lance L. Littlejohn, Mateusz Piorkowski +1
We offer a detailed treatment of spectral and Weyl-Titchmarsh-Kodaira theory for all self-adjoint Jacobi operator realizations of the differential expression \begin{align*} τ_{α,β}…
Left-Definite Variations of the Classical Fourier Expansion Theorem, Part II
Lance L. Littlejohn, Edward L. Smith, Anton Zettl
In 2002, Littlejohn and Wellman developed a general left-definite theory for arbitrary self-adjoint operators in a Hilbert space that are bounded below by a positive constant. Zett…
Donoghue -functions for singular Sturm--Liouville operators
Fritz Gesztesy, Lance L. Littlejohn, Roger Nichols +2
Let be a densely defined, closed, symmetric operator in the complex, separable Hilbert space with equal deficiency indices and denote by $\mathcal{N}_i = \ke…