Critical and subcritical Jacobi operators defined as Friedrichs extensions (Q685804)

Motivated by a treatment of the Toda lattice and Kac- von Moerbeke equations the authors study critical and subcritical 2nd-order finite difference (Jacobi) operators \(T\) on \(\mathbb{Z}\). In the course of their analysis they derive an explicit characterization of the Friedrichs extension \(T_ F\) of \(T\) in terms of principal solutions \(u_ \pm\) of \(Tu= 0\) near \(\pm\infty\).