摘要
微分算子自伴边值问题及谱理论是算子理论的重要而基本问题,它是同微分方程、数学物理和量子力学的某些重要问题相联系而发展起来的。本论文研究了微分算子乘积的自伴边值问题及一类微分算子的谱特征。
第一章 简要概述了微分算子研究的背景、进展与本文所研究的问题、使用的方法和获得的若干结果。第二章 引入本文所需要的基本知识、符号和相关的引理。
第三章 讨论了m个由同一n阶对称微分算式生成的赋予某种边界条件的微分算子乘积自伴边值问题,结合常微分算子自伴扩张的一般构造理论,分别给出了两个四阶微分算子、两个n阶微分算子、m个n阶微分算子乘积自伴边条件的解析刻划,得到了乘积微分算子是自伴的充分必要条件及与乘积算子自伴性有关的一些有益结果。第四章对区间(a,b)(-∞≤a 第五章 运用算子方法,研究了复系数J-对称微分算式生成的J-自伴微分算子谱的离散性,分别得到了一类J-自伴微分算子谱离散的充分条件与必要条件,为判断微分算子谱的离散性提供了若干准则。同时,在加权空间中,讨论了由复周期系数J-对称微分算式生成的J-自伴微分算子的本质谱,给出了一类J-自伴微分算子本质谱的存在区域。
最后,在第六章运用矩阵微分方程理论,考察了二维向量自伴Sturm-Liouville微分方程的谱,证明了在某些假设条件下,这类微分方程仅有有限多个二重特征值,进一步估计出一个下界mQ,使得当n>mQ时,特征值λ_n都是简单(一重)的。作为结果的应用,得到了两个数量型自伴Sturm-Liouville微分方程具有有限多个共同特征值的一个充分条件,并对此共同特征值的个数给出了估计。
The self-adjoint boundary-value problems and spectral theory of differential operators are important and fundamental problems in the operator theory. The self-adj oint boundary-value problems for products of differential operators and spectral properties of a class of differential operators are investigated in this dissertation.Chapter 1 deals with the background and advance of the study on the differential operators, and the main topic, some important results obtained and employed methods in this paper. Chapter 2 is some preliminaries, symbols and some lemmas.In Chapter 3, we discuss the self-adjoint boundary-value problems for products of m differential operators generated by the same symmetric differential expression of order n defined on [a, b) (-∞ < a < b ≤ ∞), endowed with some boundary conditions. Combining the general construction theory of self-adjoint extensions of ordinary differential operators, we give, respectively, analytic characterization for self-adjoint boundary conditions of products of two 4th-order differential operators, two nth-order differential operators, and m nth-order differential operators at the regular (b < ∞) and the singular (b = ∞) cases, and obtain the necessary and sufficient conditions for self-adjointness of products of differential operators. Furthermore, some useful results concerning self-adjointness of the product operator are obtained. Meanwhile, in Chapter 4, for a regular symmetric vector-valued differential expression l(y) of order n on (a,b) (-∞ < a < b ≤ ∞), under the assumption that the power expression l~2(y) is partially separated in weighted function space L_r~2(a,b), the boundary conditions determining Friedrichs extension of the minimal operator generated by l~2(y) are identified explicitly.In Chapter 5, using the approach of operators, we discuss the discreteness of the spectrum of J—self-adjoint differential operators that are generated by J—symmetric differential expression with complex-valued coefficients. Some criteria for the discrete spectrum of J—self-adjoint differential operators are obtained, which provide some criteria for the discreteness of spectrum of the differential operators. Meanwhile, we also investigate the essential spectrum of J—self-adjoint differential operators that are extended by J—symmetric differential expression with complex-valued periodic function coefficients where the underlying Hilbert space is weighted. The existence region for the essential spectrum of J—self-adjoint differential operators defined above is located.
引文
[1] N. I. Achiezer and I. M. Glazman, Theory of linear operators in Hilbert space, New York: Ungar, 1961.
[2] Z. S. Agranovich and V. A. Marchenko, The inverse problem of scattering theory, New York: Gordon and Breach, 1963.
[3] W. O. Amrein, J. M. Jauch and K. B. Sinha, Scattering theory in quantum mechanics, New York: W. A. Benajmin Inc., 1977.
[4] A. L. Andrew, Numerical solution of inverse Sturm-Liouville problems, Anziarn J., 45 (2004), 326-337.
[5] M. Arai, On essential self-adjointness of Dirac operators, RIMS Kokyuroku, 242 (1975), 10-21.
[6] M. Arai and O. Yamada, Essential self-adjointness and invariance of the essential spectrum for Dirac operators, Publ. RIMS, 18 (1982), 973-985.
[7] F. V. Atkinson, Discrete and continuous boundary pwblems, New York: Academic, 1964.
[8] F. V. Atkinson, A. M. Krall, G. K. Leaf and A. Zettl, On the numerical computation of eigenvaIues of matrix Sturm-Liouville problems with matrix coefficients, Argonne National Laboratory Reports, Darien, 1987.
[9] F. V. Atkinson and A. Mingarclli, Asymptotics of the number of zeros and of the eigenvalues of general weighted Stum-Liouville problems, J. Reine Angew. Math., 375/376 (1987), 380-393.
[10] P. B. Bailey, SLEIGN: An eigenfunction-eigenvalue code for Sturm-Liouville problems, SANDT-2044, Sandia Laboratories, Albuquerque, 1978.
[11] P. B. Bailey, B. S. Garbow, H. G. Kaper and A. Zettl, Eigenvalue and eigenfunction computations for Sturm-Liouville problems, ACM TOMS, 17 (1991), 491-499.
[12] P. B. Bailey, M. K. Gordon and L. F. Shampine, Automatic solution of the Sturm-Liouville problems, ACM Trans. Math. Software, 4 (1978), 193-208.
[13] E. Bairamov and G. B. Tunca, Discrete spectrum and principal functions of nonself-adjoint differential operator, Czechoslavak Math. J., 49 (1999), 689-700.
[14] V. Barcilon, Inverse problem for a vibrating beam in the free-clamped configuration, Phil Trans. R. Soc., 304(A) (1982), 211-251.
[15] V. Barcilon, Sufficient conditions for the solution of the inverse problem for a vibrating beam, Inverse Problems, 3 (1987), 181-193.
[16] M. Bayramoglu and K. Ozden Kokulu, Green's function of differential equation with fourth-order and normal operator coefficient in half axis, Proyecciones, Universidad Cat61ica del Notre Antofagasta-Chile, 22 (2003), 15-30.
[17] X. J. Bian, On self-adjointness of power of 2-nd order self-adjoint differential oper- ators, Acta Scientiarum Naturalium Univcrsitatis NeiMongol, 27 (1996), 1-10 (in Chinese).
[18] P. A. Binding and P. J. Browne, Asympotics of eigencurves for second order ordinary differential equations, J. Differential Equations, 88 (1990), 30-45.
[19] P. A. Binding, P. J. Browne and K. Seddighi, Sturm-Liouville problems with eigenparameter dependent boundary conditions, Proc. Edinburgh Math. Soc., 37 (1993), 57-72.
[20] P. A. Binding, P. J. Browne and B. A. Watson, Inverse spectral problems for Sturm-Liouville equations with eigenparameter dependent boundary conditions, J. London Math. Soc., 62 (2000), 161-182.
[21] P. A. Binding, P. J. Browne and B. A. Watson, Transformations between Sturm-Liouville problems with eigenvalue dependent and independent boundary conditions, Bull. London Math. Soc., 33 (2001), 749-757.
[22] P. A. Binding and H. Volkrner, Eigenvalucs for two parameter Sturm-Liouville equations, SIAM Rev., 38 (1996), 27-48.
[23] B. Birnir, Complex Hill's equation and the complex periodic Korteweg-de Vries equation, Comm. Pure Appl. Math., 39 (1986), 1-49.
[24] R. E. D. Bishop and D. C. Johnson, The Mechanic of vibration, Cambridge: Cambridge University Press, 1960.
[25] G. Brog, Eine umkehrung der Sturm-Liouvilleschen eigenwertaufgabe, Acta Math., 78 (1946), 1-96.
[26] G. Brog, Uniqueness theorems in the spectral theory of y″+(λ-q(x))y=0, Proc. 11th Scandinavian Congress of Mathematicians, Johan Grundt tanums Forlag, Oslo, 1952, 276-287. MR 15: 315a.
[27] G. E. Brown, Unified theory of nuclear models, North-Holland, Amsterdam, 1964.
[28] M. Calkin, Abstract symmetric boundary conditions, Trans. Amer. Math. Soc., 45 (1939), 369-442.
[29] C. W. Cao, On the asymptotic estimation of the trace of a partial differential operator, Scientia Sinica, Special Issue Ⅱ(1979), 56-68 (in Chinese).
[30] C. W. Cao, Asymptotic trace of a non-self-adjoint Sturm-Liouville operator, Acta Math. Sinica, 24 (1981), 84-94 (in Chinese).
[31] Z. J. Cao, On self-adjoint domain of 2-nd order differential operators in limit-circle case, Acta Math. Sinica, 1 (1985), 225-230.
[32] Z. J. Cao, On the self-adjoint extensions of higher-order ordinary differential operators in limit-circle case, Acta Math. Sinica, 28 (1985), 205-217 (in Chinese).
[33] Z. J. Cao. Ordinary differential operators, Shanghai: Shanghai Science and Technology Press, 1986 (in Chinese).
[34] Z. J. Cao and J. L. Liu, On the deficiency index theory of singular symmetric differential operators, Beijing: Advance in Math., 12 (1983), 161-178 (in Chinese).
[35] Z. J. Cao and J. Sun, Self-adjoint operator defined by quasi-derivatives, Acta Scientiarum Naturalium Universitatis NeiMongol, 17 (1986), 7-15 (in Chinese).
[36] Z. J. Cao, J. Sun and D. E. Edmunds, On self-adjointness of the product of two second-order differential operators, Acta Math. Sinica (English Ser.), 15 (1999), 375-386.
[37] R. Carlson, Expansions associated with non-self-adjoint boundary-value problems, Proceeding of the American Mathematical Society, 73 (1979), 173-179.
[38] R. Carlson, An inverse spectra problem of Sturm-Liouville operators with discontinuous coefficients, Proc. Am. Math. Soc, 120 (1994), 475-484.
[39] R. Carlson, Inverse eigenvalue problems on directed graphs, Transactions of the American Mathematical Society, 351 (1999), 4069-4088.
[40] L. Cesari, Asymptotic behavior and stability problem in ordinary differential equations, Third Edition, New York: Springer-Verlag, 1971.
[41] H. H. Chern, On the eigenvalues of some vectorial Sturm-Liouville eigenvalue problems, preprint, 1998.
[42] H. H. Chern, On the theory of matrix differential equations and the applications on the inverse and isospectral problems of Sturm-Liouville eigenvalue problems, Ph. D. Thesis, 1998 (in Chinese).
[43] H. H. Chern and C. L. Shen, On the maximum and minimum of some functionals for the eigenvalue problem of Sturm-Liouville type, Journal of Differential Equations, 107 (1994), 68-79.
[44] D. P. Clemence, On the Titchmarsh-Wcyl M(λ)-coemcient and spectral density for a Dirac system, Proc. Roy. Soc. Edinburgh, 114(A) (1990), 259-277.
[45] D. P. Clemence, M-function behaviour for a periodic Dirac system, Proc. Roy. Soc. Edinburgh, 124(A) (1994), 149-159.
[46] E. A. Coddington, The spectral representation of ordinary self-adjoint differential operators, Annals of Mathematics, 60 (1954), 192-211.
[47] E. A. Coddington and N. Lcvinson, Theory of ordinary differential equations, New York: McGraw-Hill, 1955.
[48] E. A. Coddington and N. Levinson, Theory of ordinary differential equations, New York and London, 1965.
[49] E. A. Coddington and N. Levinson, Theory of ordinary differential equations, Malabar: Krieger Publishing, 1984.
[50] E. A. Coddington and N. Lcvinson, Theory of ordinary differential equations, Marlabar, Florida: Robert E. Krieger Publishing Company, 1987.
[51] A. Constantin, A general weighted Sturm-Liouville problems, Scuola Norm. Sup. Pisa, 1997, 767-782.
[52] R. Courant and D. Hilbert, Methods of mathematics physics Ⅰ, New York: Interscience, 1953.
[53] T. Craven, G. Csordas and W. Smith, Zeros of derivatives of enter functions, Proc. Amer. Math. Soc., 101 (1987), 323-326.
[54] A. A. Danielyan and B. M. Levitan, On the asymptotic behaviour of the Weyl-Titchmarsh m-function, Math. USSR Izv., 36 (1991), 487-496.
[55] B. Despres, The Brog theorem for the vectorial Hill's equation, Inverse Problems, 11 (1995), 97-121.
[56] O. Dosly, Oscillation criteria and the discreteness of the spectrum of self-adjoint, even order, differential operators, Proc. Roy. Soc. Edinburgh, 119(A) (1991), 219-232.
[57] O. Dosly, Oscillation and spectral properties of a class of singular self-adjoint differential operators, Math. Narchr., 188 (1997), 49-68.
[58] O. Dosly, Constants in the oscillation theory of higher order Sturm-Liouville diffcrential equations, Electronic Journal of Differential Equations, vol. 2002 (2002), 1-12.
[59] A. Duksma and H. Langer, Operator theory and ordinary differential operators, Fields Inst. Monogr., 3 (1996), 75-139.
[60] N. Dunford and J. T. Schwartz, Linear operators, Part Ⅱ: Spectral theory of selfadjoint operators in Hilbert Space, Interscience Publishers, 1963, 1192-1201.
[61] N. Dunford and J. T. Schwartz, Linear operators, Part Ⅱ: Spectral theory: Seifadjoint operators in Hilbert space, New York: Wiley Classics Library Edition, 1988.
[62] H. I. Dwyer, Eigenvalues of matri Sturm-Liouville problems with separated or coupled boundary conditions, Doctoral Thesis, Northern Illinois University, 1993.
[63] H. I. Dwyer and A. Zettl, Computing eigenvalues of regular Sturm-Liouville problems, Electronic Journal of Differential Equations, vol. 1994 (1994), 1-10.
[64] H. I. Dwyer and A. Zettl, Eigenvalue computations for regular matrix Sturm-Liouville problems, Electronic Journal of Differential Equations, vol. 1995 (1995), 1-13.
[65] M. S. P. Eastham, The spectral theory of periodic differential equations, Edinburgh: Scottish Academic Press, 1973.
[66] M. S. P. Eastham, The asymptotic solution of linear differential systems, London Mathematical Society Monographs 4, Oxford: Clarendon Press, 1989.
[67] M. S. P. Eastham, Antibound states and exponentially decaying Sturm-Liouville potentials, J. London Math. Soc., 62 (2002), 624-638.
[68] M. S. P. Eastham, Q. Kong, H. Wu and A. Zettl, Inequalities among eigenvalues of Sturm-Liouville problems, J. Inequal. Appl., 3 (1999), 25-43.
[69] D. E. Edmunds and W. D. Evans, Spectral theory and differential operators, Oxford: Oxford University Press, 1987.
[70] L. H. Erbe, Boundary-value problems for ordinary differential equations, Rocky Mountain J. Math., 1 (1970), 709-729.
[71] L. H. Erbe and H. Y. Wang, On the existence of positive solutions of ordinary differential equations, Proc. Amer. Math. Soc, 120 (1994), 743-748.
[72] W. D. Evans, E. Ibrahim Sobhy, Boundary conditions for general ordinary differential operators and their adjoints, Proc. Roy. Soc. Edinburgh, 114(A) (1990), 99-117.
[73] W. N. Everitt, Notes on products of quasi-differential expressions, to appear.
[74] W. N. Everitt, Integrable-square solutions of ordinary differential equations, Oxford: Quarterly J. Math., 10 (1959), 145-155.
[75] W. N. Everitt, Self-adjoint boundary value problem on finite intervals, Journal London Math. Soc, 37 (1962), 372-384.
[76] W. N. Everitt, Integrable-square solutions of ordinary differential equations III, Oxford: Quarterly J. Math., 14 (1963), 170-180.
[77] W. N. Everitt, Singular differential equations I: the even order case, Math. Ann., 156 (1964), 9-24.
[78] W. N. Everitt, Singular differential equations II: some even order case, Oxford: Quarterly J. Math., 18 (1967), 13-32.
[79] W. N. Everitt, Integrable-square analytic solutions of odd-order, formally symmetric ordinary differential equations, Proc. London Math. Soc, 25 (1972), 156-182.
[80] W. N. Everitt, On the deficiency index problem for ordinary differential operators (1910-1976), Proceedings of the 1977 Uppsala International Conference: Differential Equations, 62-81 (Published by the University of Uppsala, Sweden; distributed by Almquist and Wiksell International, Stockholm).
[81] W. N. Everitt, Linear ordinary quasi-differential expressions, Proceedings of the 1983 Beijing Symposium on Differential Equations and Differential Geometry, 1-28 (Beijing: Science Press, 1986).
[82] W. N. Everitt and M. Giertz, On some properties of the powers of a formally self-adjoint differential expression, Proc. London Math. Soc, 24 (1972), 149-170.
[83] W. N. Everitt and M. Giertz, On the deficiency indices of powers of formally symmetric differential expressions, Lecture Notes in Mathematics, vol. 1032, Berlin/New York: Springer-Verlag, 1982.
[84] W. N. Everitt and V. K. Krishna, On the Titchmarsh-Weyl theory of ordinary symmetric differential expressions I: The general theory, Nieuw Archief voor Wiskunde, 1976, XXXIV, 1-33.
[85] W. N. Everitt and K. Krishna, On the Titchmarsh-Wcyl theory of ordinary symmetric differential expressions II: The odd-order case, Nicuw Archief voor Wiskunde, 1976, ⅩⅩⅩⅣ, 109-145.
[86] W. N. Everitt and L. Markus, The Glazman-Krein-Naimark theorm for ordinary differential operators, in new results on operator theory and its applications: The I. M. Glazman memorial volume, operator theory: Advances and applications, vol. 98, Birkho user, Basel, 1997, 118-133.
[87] W. N. Evcritt and L. Markus, Boundary. value problem and symplectic algebra for ordinary differential and quasi-differential operators, Math. Surveys and Monographs, vol. 61, Amer. Math. Soc., Providence, RI, 1999, CMP 99: 03.
[88] W. N. Everitt and L. Markus, Complex symplectic geometry with applications to ordinary differential operators, Transactions of the American Mathematical Society, 351 (1999), 4905-4945.
[89] W. N. Everitt and L. Markus, Infinite dimensional complex symplectic spaces, School of Mathematics and Statistics, Birmingham University, Preprint 2002/18, 1-17.
[90] W. N. Everitt and D. Race, Some remarks on linear ordinary quasi-differential expressions, Proc. London Math. Soc., 54 (1987), 300-320.
[91] W. N. Everitt and A. Zettl, Products of differential expressions without smoothness assumptions, Quaestiones Mathematicae, 3 (1978), 67-82.
[92] F. Fiedler, Oscillation criteria for a special class of 2nth-order ordinary differential operators, J. Differential Equations, 42 (1981), 155-185.
[93] F. Fiedler, Oscillation criteria for a special class of 2nth-order ordinary differential equations, Math. Nachr., 131 (1987), 205-218.
[94] K. O. Friedrichs, Spektractheorie Halbbeschrankter Operatoren und Anwendungen Aufdie Spektralzerlegung von Differentialoperatoren Ⅰ, Math. Ann., 109 (1934), 465-487.
[95] S. Z. Fu, On the self-adjoint extension of symmetric ordinary differential operators in direct sum spaces, J. Diff. Equa., 100 (1992), 261-291.
[96] A. Galindo, On the existence of J-self-adjoint extensions of J-symmetric operators with adjoint, Comm. Pure Appl. Math., 15 (1962), 423-425.
[97] M. G. Gasymov and T. T. Dzabiev, Solution of the inverse problem by two spectra for the Dirac equation on a finite interval, Akad. Nauk. Azerbuidzan. SSR Dokl, 22 (1966), 3-6.
[98] F. Gesztesy and B. Simon, On the determination of the potential from three spectra, Amer. Math. Soc. Transl. Ser. 2, 189 (1999), 85-92.
[99] F. Gesztesy and B. Simon, Inverse spectral analysis with partial information on the potential Ⅱ, the case of discrete spectrum, Trans. Amer. Math. Soc., 352 (1999), 2765-2787.
[100] G. M. L. Gladwell, Inverse problems in vibration, Boston: Martinus Nijhoff Pub- lishcrs, 1986.
[101] I. M. Glazman, An analogue of the extension theory of Hermitian operators and a non-symmetric one dimensional boundary value problem on half-axis, Dokl. Akad. Nayk. SSSR, 115 (1957), 214-216.
[102] I. M. Glazman, Direct methods of qualitative analysis of singular differential operators, Davey, Jerusalem, 1965.
[103] I. C. Gohberg and M, G. Krein, Theory and applications of Volterra operators in Hilbert space, Translations of Mathematical Monographs, vol. 24, American Mathematical Society, 1970.
[104] W. B. Gong and D. G. Han, Spectrum of the products of operators and compact perturbations, Proceeding of the American Mathematical Society, 120 (1994), 755-760.
[105] P. Hartman, On a theorem of Milloux, Amer. J. Math., 70 (1948), 395-399.
[106] D. B. Hinton, M. Klaus and J. K. Shaw, Levinson's theorem and Titchmarsh-Weyl theory for Dirac systems, Proc. Roy. Soc. Edinburgh, 109(A) (1988), 173-186.
[107] M. Hladnik and M. Omladic, Spectrum of the product of operators, Proc. Amer. Math. Soc, 102 (1988), 300-302.
[108] H. Hochstadt, Asymptotic estimates for the Sturm-Liouville spectrum, Commun. Pure Appl. Math., 14 (1961), 749-764.
[109] H. Hochstadt, On inverse problems associated with second order differential operators, Acta Math., 119 (1967), 173-192.
[110] H. Hochstadt, The inverse Sturm-Liouville problem, Comm. Pur. Appl. Math., 26 (1973), 715-729.
[111] H. Hochstadt, On inverse problems associated with Sturm-Liouville operators, J. Diff. Equa., 17 (1975), 220-235.
[112] H. Hochstadt and B. Lieberman, An inverse Sturm-Liouville problem with mixed given data, SIAM J. Appl. Math., 34 (1978), 676-680.
[113] M. Horvath, On the inverse spectral theory of Schrodinger and Dirac operators, Trans. Amer. Math. Soc, 353 (2001), 4155-4174.
[114] T. Ikuta and K. Shima, An approach to the spectrum structure by the localcompactness method, Proc. Amer. Math. Soc, 131 (2002), 1471-1479.
[115] Z. M. Jiang, Self-adioint domains of singular vectorial differential operators, Acta Math. Sinica, 35 (1992), 220-229 (in Chinese).
[116] Y. A. Kamimura, Criterion for the complete continuity of the resolvent of a 2nthorder differential operator with complex coefficients, Pro. Royal Soc. Edinburgh, 116(A) (1990), 161-176.
[117] H. G. Kaper and M. K. Kwong, Oscillation theory for linear second order differential systems, in Oscillation, bifurcation and chaos (F. V. Atkinson, et al, eds.), Canad. Math. Soc., Conference Proceedings, 8 (1986), 187-197.
[118] T. Kato, Perturbation theoryfor linear operators, New York: Springer, 1995.
[119] R. M. Kauffman, Factorization and the Friedrichs extension for ordinary diffetrentiaI operators, Lecture Notes in Mathematics, vol. 1032, Berlin/New York: Springer-Verlag, 1982.
[120] R. M. Kauffman, T. Read and A. Zettl, The deficiency index problem of powers of ordinary differential expressions, Lecture Notes in Mahematics, vol. 621, Berlin/New York: Springer-Verlag, 1977.
[121] J. B. Keller, The minimum ratio of two cigenvalues, SIAM J. Appl. Math., 31 (1976), 485-491.
[122] D. E. Kerr, Propagation of short radio waves, Boston Lexington: Technical Publishers, 1964.
[123] A. Kirsch, An intwduction to the mathematical theory of inverse problems, New York: Springer, 1996.
[124] I. W. Knowles, Note on a limit-point criterion, Proc. Amer. Math. Soc., 41 (1973), 117-119.
[125] I. W. Knowles, On J-self-adjoint extensions of J-symmetric operators, Proc. Amer. Math. Soc., 79 (1980), 42-44.
[126] I. W. Knowles, On the boundary conditions characterizing J-self-adjoint extensions of J-symmetric operators, J. Diff. Equa., 40 (1981), 193-216.
[127] I. W. Knowles and D. Race, On the point spectra of complex Sturm-Liouville operators, Proc. Roy. Soc. Edinburgh, 85(A) (1980), 263-289.
[128] K. Kodaira, On ordinary differential equations of any even order and the corresponding eigenfunction expansion, American J. Math., 72 (1950), 502-544.
[129] Q. Kong, H. Wu and A. Zettl, Dependence of eigenvalues on the problems, Math. Nachr., 188 (1997), 173-201.
[130] Q. Kong, H. Wu and A. Zettl, Dependence of the nth Sturm-Liouville eigenvalue on the problems, J. Differential Equations, 156 (1999), 328-354.
[131] Q. Kong, H. Wu and A. Zettl, Left-definite Sturm-Liouville problem, J. Differential Equations, 177 (2001), 1-26.
[132] Q. Kong, H. Wu and A. Zettl, Sturm-Liouville problems with finite spectrum, J. Math. Anal. Appl., 263 (2001), 748-762.
[133] Q. Kong and A. Zettl, Eigenvalues of regular Sturm-Liouville problems, J. Differential Equations, 131 (1996), 1-19.
[134] J. Kozul and Y. M. Zou, Introduction to Symplectic Geometry, Beijing: Science Press, 1986 (in Chinese).
[135] M. G. Krein, On certain problems on the maximum and minimum of characteristic values and on the Lyapunov zones of stability, Amer. Math. Soc. Transl., 1 (1995), 163-187.
[136] A. Laptev, S. Naboko and 0. Safronov, A SZEGO condition for a multidimensional Schrodinger operator, Institute Mittag-Leffler, The Royal Swedish Academy of Sciences, Report No. 17, 2002/2003, fall.
[137] C. K. Law, C. L. Shen and C. F. Yang, The inverse nodal problem on the smoothness of the potential function, Inverse Problems, 15 (1999), 253-263.
[138] C. K. Law and C. F. Yang, Reconstructing the potential function and its derivatives using nodal data, Inverse Problems, 14 (1998), 299-312.
[139] A. C. Lazer, A stability condition for the differential equation y" + p(x)y = 0, Michigan Math. J., 12 (1965), 193-196.
[140] B. Ya. Levin, Distribution of zeros of entire functions, Moscow: GITTL, 1956 (in Russian).
[141] B. Ya. Levin, Transforms of the Fourier-Laplace type by means of solutions of second order differential equations, DAN SSSR., 1958, 187-189 (in Russion).
[142] B. Ya. Levin, Distribution of zeros of entire functions, Translations of Mathematical Monographs, Amer. Math. Soc, vol. 5, 1964.
[143] N. Lcvinson, The inverse Sturm-Liouvillc problem, Matematisk Tidsskrift, B (1949), 25-30.
[144] B. M. Lcvitan, Inverse Sturm-Liouville problems, VNU Science Press, 1987.
[145] B. M. Levitan and M. G. Gasymov, Determination of a differential equation by two of its spectra, Uspekhi. Mat. Nauk, 19 (1964), 3-63, Russian Mathematical Surveys, 19 (1964), 1-63.
[146] B. M. Levitan and I. S. Sargsjan, Introduction to spectral theory, Translations of Mathematical Monographs, Amer. Math. Soc, vol. 39, 1975.
[147] B. M. Lcvitan and I. S. Sargsjan, Sturm-Liouville and Dirac operators(in Russian), Nauks Moscow, 1988: English transl. MR 921: 34119.
[148] B. M. Levitan and I. S. Sargsjan, Sturm-Liouville and Dirac operators, Kluwer Academic Publishers, 1991.
[149] W. M. Li, The higher-order differential operators in direct sum spaces, J. Diff. Equa., 84 (1990), 273-289.
[150] W. M. Li, Self-adjoint extensions for ordinary differential operator in the vector- valued function space, Acta Scientiarum Naturalium Universitatis NeiMongol, 22 (1991), 447-454 (in Chinese).
[151] Y. S. Li, On an inverse eigenvalue problem for a second order differential equation with boundary dependence on the parameter, Acta Math. Sinica, 15 (1965), 375- 381 (in Chinese).
[152] V. B. Lidskii, A non-self-adjoint operator of Sturm-Liouville type with a discrete spectrum, Trudy Moskov Math. Obshch., 1 (1960), 45-79 (in Russion).
[153] V. B. Lidskii, Conditions for completeness of a system of root subspace for non-selfadjoint operators with discrete spectra, Trudy Moscow. Math. Obshch., 8 (1959), 83-120 (in Russian). English translations: Amer. Math. Transl., 34 (1963), 241-281.
[154] T. C. Lim, Some L~p inequalities and their applications to fixed point theorems of uniformly Lipschitzian mappings, Proc. Amer. Math. Soc., 45 (1986), Part Ⅱ, 119-125.
[155] J. L. Liu, On the limit-point classification of a class of non-self-adjoint ordinary differential operators, J. Diff. Equa., 55 (1984), 165-203.
[156] J. L. Liu, On the limit-point classification of powers of a class of non-self-adjoint differential operators, Ann. Diff. Equa., 8 (1992), 323-333.
[157] J. L. Liu, On J-sclf-adjoint extensions of J-symmetric operators, Acta Scientiarum Naturalium Universitatis NeiMongol, 23 (1992), 312-316 (in Chinese).
[158] J. L. Liu, On the Calkin approach of self-adjoint extensions of symmetric operators, J. Inner Monogolia Univ., 19 (1988), 573-587 (in Chinese).
[159] M. Marletta and A. Zettl, The Friedrichs extension of singular differential operators, J. Diffrential Equations., 160 (2000), 404-421.
[160] D. Mcduff and D. Salamon, Introduction to symplectic topology, Oxford: Oxford University Press, 1995.
[161] H. Mckean and P. Van Mocrbeke, The spectrum of Hill's equatuion, Inventions Math., 30 (1975), 217-274.
[162] J. R. McLaughlin, On constructing solutions to an inverse Euler-Bernoulli problem, in "Inverse problem of acoustic and elastic waves", 341-347, F. Santosa, et al.(editors), Philadelphia: SIAM, 1984.
[163] J. R. McLaughlin, Inverse spectral theory using nodal points as data-a uniqueness result, J. Diff. Equa., 73 (1988), 354-362.
[164] A. Meir, D. Willett and J. S. Wong, A stability condition for y″+p(x)y=0, Michigan Math. J., 13 (1966), 169-170.
[165] A. M. Molchanov, The conditions for the discreteness of the spectrum of self-adjoint second order differential equation, Trudy Moskov. Mat. Obsh., 2 (1953), 169-200.
[166] M. Moller and A. Zettl, Semi-boundedness of ordinary differential operators, J. Diff. Equa., 115 (1995), 24-49.
[167] M. Moller and A. Zettl, Symmetric differential operators and their Friedrichs extension, J. Differential Equations., 115 (1995), 50-69.
[168] P. E. Muller, Spectrum theory of ordinary differential operators, Chichester: Ellis Hopwood Limited, 1981.
[169] P. E. Muller and J. Sun, On the discrete spectrum of ordinary differential operators in weighted function spaces, Zeitschrift fur Analysis und ihre Anwendungen, 14 (1995), 637-646.
[170] M. A. Naimark, On the deficiency index of linear differential operators, C. R. (Doklady) Akad. Sci. USSR, 82 (1952), 517-520.
[171] M. A. Naimark, Investigation of the spectrum and expansion in eigenfunctions of a non-self-adjoint second order differential operator on a semi-axis, Trudy Mosksov. Mat. Ovsh., 3 (1954), 181-270 (in Russion).
[172] M. A. Naimark, Linear differential operators, Part Ⅰ and Ⅱ, New York: Frederick Ungar Publishing Co., 1967 and 1968.
[173] H. D. Niessen and A. Zettl, The Friedrichs extension of regular ordinary differential operators, Pro. Roy. Soc. Edinburgh, 114(A) (1990), 229-236.
[174] V. G. Papanicolaou, The periodic Euler-Bernoulli equation, Transactions of the American Mathematical Society, 351 (1999), 4069-4088.
[175] V. G. Papanicolaou, The spectral theory of the vibrating periodic beam, Commun. Math. Phys., 355 (2003), 3727-3759.
[176] V. G. Papanicolaou and D. Kravvaritis, An inverse spectral problem for the Euler-Bernoulli equation for the vibrating beam, Inverse Problems, 13 (1997), 1083-1092.
[177] M. Plum, Eigenvalue inclusions for second order ordinary differential operators by a numerical homotopy method, Journal of Applied Mathematics and Physics (ZAMP), 41 (1990), 205-226.
[178] J. Poschel and E. Trubowitzm, The reverse spectral theory, New York: Academic, 1987.
[179] C. Prather, Zeros of operators on real entire functions of order less than two, J. Math. Anal. Appl., 17 (1986), 81-83.
[180] S. Pruess and C. Fulton, Mathematical software for Sturm-Liouvlle problems, ACM TOMS (1994), to appear.
[181] J. D. Pryce, Numerical solution of Sturm-Liouville problems, Oxford: Oxford University Press, 1993.
[182] D. Race, On the location of the essential spectra and regularity fields of complex Sturm-Liouville operators, Proc. Edinburgh, 85(A) (1980), 1-14.
[183] D. Race, On the essential spectra of linear 2nth-order differential operator with complex coefficients, Pro. Royal Soc. Edinburgh, 92(A) (1982), 65-75.
[184] D. Race, The theory of J-self-adjoint extensions of J-symmetric operators, J. Diff. Equa., 57 (1985), 258-274.
[185] D. Race and A. Zettl, On the commutativity of certain quasi-differential expression Ⅰ, J. London Math. Soc., 42 (1990), 489-504.
[186] D. Race and A. Zettl, Characterization of the factors of quasi-differential expressions, Proc. Royal. Soc. Edinburgh, 123(A) (1993), 27-43.
[187] T. T. Read, Perturbations of limit-circle expressions, Proc. Amer. Math. Soc., 96 (1976), 108-110.
[188] M. Reed and B. Simon, Methods of mordern mathematical physics Ⅰ, New York: Academic Press, 1972.
[189] M. Reed and B. Simon, Methods of modern mathematical physics Ⅱ, Fourier analysis, Self-adjointness, San Diego: Academic Press, 1975.
[190] M. Reed and B. Simon, Methods of modern mathematical physics Ⅳ, Analysis of operators, New York: Academic Press, 1978.
[191] W. Rudin, Functional analysis, Second Edition, Beijing: China Machine Press, 2004.
[192] W. Rundell and P. E. Sacks, Reconstruction techniques for classical inverse Sturm-Liouville problems, Math. Comp., 58 (1992), 161-183.
[193] J. Santanilla, Nonnegative solutions to boundary value problems for nonlinear first and second order differential equations, J. Math. Anal. Appl., 126 (1987), 397-408.
[194] M. Schechter, Operator methods in quantum mechanics, North Holland, New York, Oxford, 1981.
[195] E. Schrodinger, Quantisierung als Enigenwertproblcm, Ann. D. Falge, 79(Ⅳ) (1929), 631-642.
[196] Z. J. Shang, On J-self-adjoint extensions of J-symmetric ordinary differential operators, J. Diff. Equations, 73 (1988), 153-177.
[197] Z. J. Shang, Notes on J-sclf-adjoint extensions of J-symmetric ordinary differential operators, Acta Math. Sinica, 39 (1996), 387-398 (in Chinese).
[198] Z. J. Shang and R. Y. Zhu, The domain of self-adjoint extensions of ordinary symmetric differential operator over (-∞, ∞), Acta Sci. Natur. Univ. NeiMongol, 17 (1986), 17-28 (in Chinese).
[199] C. L. Shen, On the second eigenvalue and the second eigenfunction of a class of selfadjoint second order linear systems, Rocky Mountain Journal of Math., 23 (1993), 1431-1442.
[200] C. L. Shen, On the asymptotic behavior of solutions of a class of self-adjoint second order linear systems, Rocky Mountain Journal of Math., 27 (1997), 635-634.
[201] C. L. Shen, On the nodal sets of the eigenfunctions of the string equation, SIAM J. Math., 19 (1998), 1419-1424.
[202] C. L. Shen and C. T. Shieh, Two inverse eigenvalue problems for vectorial Sturm-Liouville equations, Inverse Problems, 14 (1998), 1331-1343.
[203] C. L. Shen and C. T. Shieh, On the multiplicity of eigenvalues of a vectorial Sturm-Liouville differential equation and some related spectral problems, Proc. Amer. Math. Soc., 127 (1999), 2943-2952.
[204] C. L. Shen and C. T. Shieh, An inverse nodal problem for vectorial Sturm-Liouville equations, Inverse Problems, 16 (2000), 349-356.
[205] C. L. Shen and T. M. Tsai, On a uniform approximation of the density function of a string equation using eigenvalues and nodal points and some related inverse nodal problems, Inverse Problems, 11 (1995), 1113-1123.
[206] B. Simon, Some Schrodinger operators with dense point spectrum, Proc. Am. Math. Soc, 125 (1997), 203-208.
[207] B. Simon, Schrodinger operators in the twentieth century, J. Math. Phys., 41 (2000), 3523-3555.
[208] I. Stakgold, Boundary value problems and Green's function, New York, 1998.
[209] J. Sun, On self-adjoint extensions of singular symmetric differential operators with middle deficiency indices, Acta Math. Sinica, 2 (1986), 152-167.
[210] J. Sun and Z. Wang, The qualitative analysis of the spectrum of ordinary differential operators, Beijing: Adv. in Math., 24 (1995), 406-422 (in Chinese).
[211] P. Sy and T. Sunada, Discrete Schrodinger operators on a graph, Nagoya Mat. Journal, 125 (1992), 141-150.
[212] A. E. Taylor and D. C. Lay, Introduction to functional analysis, New York: Wiley, 1980.
[213] W. Thirring, Quantum mechanics of atoms and molecules, New York: Springer, 1981.
[214] E. C. Titchmarsh, Eigenfunction expansions associated with second order differential equations, Part I, Oxford: Oxford University Press, 1946.
[215] E. C. Titchmarsh, Eigenfunction expansions, Part I, 2nd edn, Oxford: Oxford University Press, 1962.
[216] V. Tkachenko, Spectra of non-self-adjoint Hill's operators and a class of Riemann surfaces, Ann. Math., 143 (1996), 181-231.
[217] E. Trubowitz, The inversc problem for periodic potentials, Communications on Pure and Applied Mathematics, 3 (1977), 321-337 .
[218] G. B. Tunca, Spectral expansion of a non-self-adjoint differential operator on the whole axis, Journal of Mathematical Analysis and Applications, 252 (2000), 278-297.
[219] W. Y. Wang, Complex J-symplectic geometry with application to ordinary differential operators, Beijing: Adv. in Math., 30 (2001), 277-278.
[220] W. Y. Wang and J. Sun, Complex symplectic geometry characterization for selfadjoint domains for 2nth-order non-singular differential operators, Math. Appl., 16 (2003), 17-22 (in Chinese).
[221] W. Y. Wang and J. Sun, Complex J-symplectic geometry characterization for J-symmectric extensions of J-symmectric differential operators, Beijing: Adv. in Math., 32 (2003), 481-484.
[222] Z. Wang, A sufficient condition on discrete spectrum of 2nth-order differential operator with complex coefficients, Acta Scientiarum Naturalium Universitatis Nci- Mongol, 28 (1997), 305-307 (in Chinese).
[223] Z. Wang, The qualitative analysis of the spectrum of non-self-adjoint differential operators, Ph. D. Thesis, Inner Mongolia University, 1999 (in Chinese).
[224] Z. Wang, The spectrum of 2nth-order differential operators with complex coefficients, Acta Mathcmatica Sinica, 43 (2000), 787-796 (in Chinese).
[225] Z. Wang and J. Sun, The qualitative analysis of the spectrum of J-self-adjoint differential operators, Beijing: Adv. in Math., 30 (2001), 405-413 (in Chinese).
[226] Z. Wang and J. Sun, The discreteness of the spectrum of second order one-term J-self-adjoint differential operators, Acta Scientiarum Naturalium Universitatis Nei-Mongol, 32 (2001), 487-491 (in Chinese).
[227] Z. Wang and R. F. Yang, The resolvent operators of higher-order J-self-adjoint differential operators, Acta Scientiarum Naturalium Universitatis NeiMongol, 28 (1997), 330-334 (in Chinese).
[228] B. A. Watson, Inverse spectral problems for weighted Dirac system, Inverse Problems, 15 (1999), 793-805.
[229] G. S. Wei, A new description of self-adjoint domains of symmetric operators, J. Inner Monogolia Univ., 27 (1996), 305-310 (in Chinese).
[230] G. S. Wci, Z. B. Xu and J. Sun, Self-adjoint domains of products of differential expressions, J. Differential Equations, 174 (2001), 75-90.
[231] J. Weidmann, Linear Operators in Hilbert Spaces, Graduate Text in Mathematics, vol. 68, Berlin: Springer-Verlag, 1980.
[232] J. Weidmann, Spectral theory of ordinary differential operators, Lecture Notes in Mathematics, vol. 1258, Berlin/New York: Springer-Verlag, 1987.
[233] R. Weikard, On Hill's equation with a singular complex-valued potential, Proc. London Math. Soc., 76 (1998), 603-633.
[234] H. Weyl, Uber Gcwohnliche Differential Gleichungen Mit Singularityten und Kie Zugehorigen Entwicklungen Willkurlicher Funktionen, Math. Ann., 68 (1910), 220-269.
[235] P. Y. Wu, Products of normal operators, Canad. J. Math., 40 (1988), 1322-1330.
[236] O. Yamada, On the spectrum of Dirac operators with the unbounded potential at infinity, Hokkaido Math. J., 26 (1997), 439-449.
[237] C. F. Yang, Z. Y. Huang and X. P. Yang. Sclf-adjointness of products of n Schrodinger operators, Journal of Nanjing University Mathematical Biquarterly, 21 (2004), 43-53.
[238] C. F. Yang, Z. Y. Huang and X. P. Yang, Self-adjointness of products of two 4thorder differential operators, Beijing: Advances in Mathematics, 33 (2004), 291-302 (in Chinese).
[239] C. F. Yang, Z. Y. Huang and X. P. Yang, Self-adjointness of products of m differ- ential operators in the Hilbert space L~2[a, b], Mathematica Applicata, 17 (2004), 617-622 (in Chinese).
[240] C. F. Yang, Y. P. Wang, Self-adjoint boundary-value problem for products of limitpoint fourth-order differential operators, Journal of Nanjing University of Science and Technology (Natural Science), 29 (2005), 116-118 (in Chinese).
[241] C. F. Yang, Z. Y. Huang and X. P. Yang, Complex symplectic geometry characterizations for symmetric extensions and Friedrichs extensions of differential operators, accepted to appear in Acta Mathematica Sinica.
[242] C. F. Yang, Z. Y. Huang and X. P. Yang, A necessary and sufficient condition for self-adjointness of the product differential operator, accepted to appear in Acta Mathematica Scientia.
[243] C. F. Yang, Z. Y. Huang and X. P. Yang, The multiplicity of spectra of a vectorial Sturm-Liouville differential equation of dimension two and some applications, accepted to appear in Rocky Mountain Journal of Mathematics.
[244] C. F. Yang, Z. Y. Huang and X. P. Yang, A new characterization for self-adjoint domains of products of m differential expressions, submitted.
[245] C. F. Yang, Z. Y. Huang and X. P. Yang, Criteria for the discrete spectrum of even-order non-symmetric differential operators, submitted.
[246] C. F. Yang, Boundedness from below and spectrum of a class of higher-order Sturm-Liouville differential operators in L~2[a, ∞), submitted.
[247] X. F. Yang, A solution of the inverse nodal problem, Inverse Problems, 13 (1997), 203-213.
[248] K. Yosida, On Titchmarsh-Kodaira's formula concerning Weyl-Stone's eigenfunction expansion, Nagoya Math. J., 1 (1950), 49-58.
[249] K. Yosida, Functional analysis, Berlin-Gottingen-Heidelberg: Springer Verlag, 1980.
[250] C. Yu, Trace asymptotic for Schrodinger operator on domains with fractal boundaries, Beijing: Adv. in Math., 32 (2003), 503-505.
[251] X. P. Yuan, Regular Sturm-Liouville problems with mixed self-adjoint boundary conditions, J. Inner Mongolia University, 21 (1990), 35-41 (in Chinese).
[252] B. N. Zakhariev and A. A. Suzko, Direct and inverse problems, Berlin: Springer, 1990.
[253] A. Zettl, Formally self-adjoint quasi-differential operators, Rocky Mountain J. Math., 5 (1975), 453-474.
[254] A. Zettl, Powers of symmetric differential expressions without smoothness assumptions, Quaestiones Mathematicae, 1 (1976), 83-94.
[255] A. Zettl, Sturm-Liouville problems, in "Spectrum theory and computational methods of Sturm-Liouville problems" (D. Hinton and P. Schaefer, Eds.), Lecture Notes in