Download or read book S-Essential Spectra and the Weyl Pseudospectra of Linear Operators written by Ammar Aymen and published by LAP Lambert Academic Publishing. This book was released on 2015-10-22 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we present a spectral study of semi regular operator. The concept of semi regularity and essentially semi regularity amongst the various concepts of regularity originating from Fredholm theory, and we introduce new notions and unprecedented denition to develop pseudospectral theory. We built our denition on the basis of essential spectra and tried to comply it with pseudospectral theory. So, we intend to obtain what we call "Weyl pseudospectra."