Electronic Journal of Differential Equations,
Vol. 2012 (2012), No. 210, pp. 1-8.

Title: Spectrum of the direct sum of operators
        
Authors: Elif Otkun Cevik     (Karadeniz Technical Univ., Trabzon, Turkey)
         Zameddin I. Ismailov (Karadeniz Technical Univ., Trabzon, Turkey)

Abstract:
 We study the connection between spectral properties
 of direct the sum of operators in the direct sum of Hilbert spaces
 and its coordinate operators.
 
Submitted November 30, 2011. Published November 27, 2012.
Math Subject Classifications: 47A10.
Key Words: Direct sum of Hilbert spaces; spectrum; resolvent set;
           compact operators; discrete spectrum; eigenvalues.