报告题目：On essential spectra and essential numerical ranges of Hamiltonian systems

报告人：孙华清 教授 江苏师范大学

报告时间：2025年12月4日（星期四） 9:30-12:00

腾讯会议：300-795-741                

主持人：李万同 教授  兰州大学

校内联系人：苏远航 副教授 联系电话：84708351-8302

报告摘要： This talk is concerned with essential spectra and essential numerical ranges of Hamiltonian systems with one singular endpoint. The characterization of each element of the essential spectrum in terms of certain singular sequences is given, the concept of perturbation small at the singular endpoint is introduced, and the stability of the essential spectrum is obtained under this perturbation. Some sufficient conditions for the invariance of the essential spectrum are given in terms of coefficients of Hamiltonian systems. In addition，corresponding results are obtained for the essential numerical ranges of semi-bounded systems.

报告人简介：孙华清，江苏师范大学，教授、博导，一直从事奇异微分与差分算子谱理论研究，在“J. Funct. Anal.”，“J. Differential Equations”，“Proc. Roy. Soc. Edinburgh Sect. A”， “Math. Nachr”等国际权威杂志上发表30多篇 SCI 收录的论文，先后国家自然科学基金以及其它省部级项目多项。