Pathology of essential spectra of elliptic problems in periodic family of beads threaded by a spoke thinning at infinity
Summary: We construct ``almost periodic'' unbounded domains, where a large class of elliptic spectral problems have essential spectra possessing peculiar structure: they consist of monotone, non-negative sequences of isolated points and thus have infinitely many gaps.
scientific article; zbMATH DE number 7367175
scientific article