FIRST DESCRIPTION OF ESSENTIAL SPECTRUM

WEYL, HERMANN.

Über gewöhnliche Differentialgleichungen mit Singularitäten und die zugehörigen Entwicklungen willkürlicher Funktionen.

Leipzig, B.G. Teubner, 1910. 8vo. Original printed wrappers, no backstrip and a small nick to front wrapper. In "Mathematische Annalen. Begründet durch Alfred Clebsch und Carl Neumann. 68. Band. 2. Heft."Entire issue offered. Internally very fine and clean. [Weyl:] Pp. 220-69. [Entire issue: Pp. 145-304].

First printing of Weyl's important paper in which he created the topic of essential spectrum.
In mathematics, the essential spectrum is a certain subset of its spectrum, defined by a condition of the type that says, "fails badly to be invertible".

Order-nr.: 44577