On scarcity of operators with finite spectrum
نویسندگان
چکیده
منابع مشابه
Diagonals of normal operators with finite spectrum.
Let X={lambda1, ..., lambdaN} be a finite set of complex numbers, and let A be a normal operator with spectrum X that acts on a separable Hilbert space H. Relative to a fixed orthonormal basis e1, e2, ... for H, A gives rise to a matrix whose diagonal is a sequence d=(d1, d2, ...) with the property that each of its terms dn belongs to the convex hull of X. Not all sequences with that property c...
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The spectral analysis of two classes of third order boundary value problems is investigated. For every positive integer $m$ we construct two classes of regular third order boundary value problems with at most $2m+1$ eigenvalues, counting multiplicity. These kinds of finite spectrum results are previously known only for even order boundary value problems.
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ژورنال
عنوان ژورنال: Bulletin of the American Mathematical Society
سال: 1976
ISSN: 0002-9904
DOI: 10.1090/s0002-9904-1976-14066-9