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The Well-Posed Operators with Their Spectra in Lpw-Spaces
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2023年第6期347-368,共22页
In this paper, we have considered the general ordinary quasi-differential operators generated by a general quasi-differential expression τ<sub>p,q</sub> in L<sup>p</sup>w</sub>-spaces of... In this paper, we have considered the general ordinary quasi-differential operators generated by a general quasi-differential expression τ<sub>p,q</sub> in L<sup>p</sup>w</sub>-spaces of order n with complex coefficients and its formal adjoint τ<sup>+</sup><sub>q',p' </sub>in L<sup>p</sup>w</sub>-spaces for arbitrary p,q∈[1,∞). We have proved in the case of one singular end-point that all well-posed extensions of the minimal operator T<sub>0</sub> (τ<sub>p,q</sub>) generated by such expression τ<sub>p,q</sub> and their formal adjoint on the interval [a,b) with maximal deficiency indices have resolvents which are Hilbert-Schmidt integral operators and consequently have a wholly discrete spectrum. This implies that all the regularly solvable operators have all the standard essential spectra to be empty. Also, a number of results concerning the location of the point spectra and regularity fields of the operators generated by such expressions can be obtained. Some of these results are extensions or generalizations of those in the symmetric case, while others are new. 展开更多
关键词 Quasi-Differential Expressions Regular and Singular Endpoints Minimal and Maximal operators regularly solvable operators Well-Posed operators Deficiency Indices
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On the Domains of General Ordinary Differential Operators in the Direct Sum Spaces
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作者 Sobhy El-Sayed Ibrahim 《Advances in Pure Mathematics》 2022年第3期206-228,共23页
Given general quasi-differential expressions , each of order n with complex coefficients and their formal adjoint are on the interval [a,b) respectively, we give a characterization of all regularly solvable operators ... Given general quasi-differential expressions , each of order n with complex coefficients and their formal adjoint are on the interval [a,b) respectively, we give a characterization of all regularly solvable operators and their adjoints generated by a general ordinary quasi-differential expression in the direct sum Hilbert spaces . The domains of these operators are described in terms of boundary conditions involving -solutions of the equations and their adjoint on the intervals [a<sub>p</sub>,b<sub>p</sub>). This characterization is an extension of those obtained in the case of one interval with one and two singular end-points of the interval (a,b), and is a generalization of those proved in the case of self-adjoint and J-self-adjoint differential operators as a special case, where J denotes complex conjugation. 展开更多
关键词 Quasi-Differential Expressions Regular and Singular Equations Minimal and Maximal operators regularly solvable operators J-Self-Adjoint Extension Boundary Conditions
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Symplectic Structures of Two Kinds of Nonsymmetric Differential Operators
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作者 Wei-hua YANG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2015年第2期543-556,共14页
Non-self-adjoint quasi-differential expression M and its formal adjoint M+may generate nonsymmetric ordinary differential operators. Although minimal operators T0, T+0 generated by M, M+are not symmetric, they form... Non-self-adjoint quasi-differential expression M and its formal adjoint M+may generate nonsymmetric ordinary differential operators. Although minimal operators T0, T+0 generated by M, M+are not symmetric, they form an adjoint pair. In this paper, author studies regularly solvable operators with respect to the adjoint pair T0, T+0 in two kinds of conditions and give their geometry description in the corresponding ways. 展开更多
关键词 regularly solvable operators symplectic space self-adjoint operator pair
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