2003/08/27 by Kwang C. Shin
Physics and Astronomy · Mathematics · #math-ph #math.MP
published as Math. Nachr. 261-262: 171-175 (2003) · 6 pages; no figure; to appear in Math. Nachr
arxiv created 2003/08/27 · arxiv updated 2009/12/01
In 1980, Gasymov showed that non-self-adjoint Hill operators with complex-valued periodic potentials of the type V(x)=∑k=1∞ ak eikx, with ∑k=1∞|ak|<∞, have spectra [0, ∞). In this note, we provide an alternative and elementary proof of this result.