Ornstein-Zernike and analyticity properties for classical lattice spin systems

The leading Ornstein-Zernike behavior of the truncated two-point function G(x) is obtained from information on the poles of the Fourier transform G~(p). Analyticity of G~(p) as a function of the complex variables p and the inverse temperature β is studied in detail for |β| sufficiently small.     

Linear differential equations and functional analysis,V

Mathematische Annalen -     

Linear differential equations and functional analysis. IX. Almost periodic equations

During the writing of the author's doctoral dissertation on almost periodic differential equations, he received valuable suggestions from ProfessorB. L. van der Waerden concerning the theory of stability of linear equations; these suggestions became an important germ of the author's contribution to the series of papers to which this is the latest addition. It is but fitting that, the wheel having come full circle, this chapter on almost periodic equations should be dedicatedto Professorvan der Waerden on his 60th birthday.