应学院及我院胡泽军教授的邀请，法国瓦朗西纳大学（Université de Valenciennes）Luc Vrancken教授将于5月2日至8日率领瓦朗西纳大学Elsa Ghandour博士（后）和比利时天主教鲁汶大学（Katholieke Universiteit Leuven）Anna Wijffels博士前来郑州大学进行学术访问，并就共同感兴趣的微分几何课题展开深入地学术研讨。
        访问期间，Luc Vrancken教授和Elsa Ghandour、Anna Wijffels两位博士将分别做学术报告。报告的具体安排如下：

一、报告题目：Lagrangian submanifolds of the complex hyperbolic quadric

        报告人：Anne Wijffels博士

        时间：2019年5月5日（星期日）下午15:30—16:30.

        地点：数学与统计学院办公楼310报告室

        报告内容提要：We will introduce the basic results related to the complex hyperbolic quadric. Particularly, we are interested in the study of the Lagrangian immersions in the complex hyperbolic quadric. Moreover, in this talk, we will present our recently classification of all the minimal Lagrangian submanifolds with constant sectional curvature.

二、报告题目：Generalized harmonic morphisms and semi-conformal biharmonic maps
        报告人：Elsa Ghandour博士
        时间：2019年5月5日（星期日）下午16:30—17:30.
        地点：数学与统计学院办公楼310报告室
       报告内容提要：Harmonic morphisms, mapping which pull back local harmonic functions to harmonic functions, have played an important role in understanding the relation between the geometry and topology of Riemannian manifolds. Various attempts have been made to adapt the notion to other situations. None of these have been satisfactory due to the complexity of the characterizing equations and the lack of examples. In this work, we introduce a new notion of generalized harmonic morphisms that have an elegant characterization which enables the construction of explicit examples, as well as impacting on the theory of biharmonic mappings.

三、报告题目：Warped product hypersurfaces
        报告人：Luc Vrancken教授
        时间：2019年5月7日（星期二）上午11:00—12:00.
        地点：数学与统计学院教学楼303教室
        报告内容摘要：Classical examples of warped product hypersurfaces in a real space form are the rotational hypersurfaces. In this talk, we show that in some sense the reverse statement is also true, i.e. let M be a warped product manifold of an interval with a real space form and assume that M is contained as a hypersurface in a real space form. Then either M is itself a space of constant sectional curvature, or M is a rotational hypersurface in the sense of Dajczer and Do Carmo. In the Riemannian case this result was obtained by Dajczer and Tojeiro. We generalize it here to arbitrary pseudo-Riemannian case.

欢迎广大师生参加。

         Luc Vrancken教授简介：Luc Vrancken教授1964年出生于比利时，博士毕业于比利时天主教鲁汶大学，1999-2000年在德国柏林工业大学做洪堡访问学者,2002年至今任法国瓦朗西纳大学教授和比利时天主教鲁汶大学兼职教授。Luc Vrancken教授是国际上知名的微分几何学家，先后发表学术论文210余篇，论文被SCI论文引用1400余次。Luc Vrancken教授在微分几何的很多方面、特别是局部仿射微分几何的诸多领域都有重要贡献。在仿射超曲面研究中他独立地解决了著名的Magid-Ryan猜想(J. Differ. Geom. 54: 99-138, 2000)、他与我院胡泽军教授和清华大学李海中教授合作，完成了“具有平行Fubini-Pick形式的局部严格凸仿射超曲面的完全分类”(J. Differ. Geom. 87: 239-307, 2011)。Luc Vrancken教授自2009年以来已先后8次访问郑州大学，与我院胡泽军教授领导的微分几何学研究团队开展了卓有成效的合作研究。以下是多年来我院微分几何团队与Luc Vrancken领导下的微分几何团队合作完成的主要研究成果：

1. Zejun Hu, Haizhong Li and Luc Vrancken: Characterisations of the Calabi product of hyperbolic affine hyperspheres, Results in Mathematics, 52(2008), 299-314.

2. Zejun Hu, Haizhong Li, Udo Simon and Luc Vrancken：On locally strongly convex affine hypersurfaces with parallel cubic form, Part I, Differential Geometry and Its Applications, 27 (2009) ,188–205.

3. Zejun Hu, Haizhong Li and Luc Vrancken：Locally strongly convex affine hypersurfaces with parallel cubic form, Journal of Differential Geometry, 87 (2011), 239–307.

4. Zejun Hu, Cece Li, Haizhong Li and Luc Vrancken：Lorentzian affine hypersurfaces with parallel cubic form, Results in Mathematics, 59(2011), 577-620.

5. Zejun Hu, Cece Li, Haizhong Li and Luc Vrancken：The classification of 4-dimensional non-degenerate hypersurfaces with parallel cubic form, Journal of Geometry and Physics, 61(2011), 2035-2057.

6. Miroslava Antic, Zejun Hu, Cece Li and Vrancken Luc：Characterizations of the generalized Calabi composition of affine hyperspheres, Acta Mathematica Sinica, English Series, 31(10) (2015), 1531–1554.

7. Yinshan Zhang, Bart Dioos, Zejun Hu, Luc Vrancken and Xianfeng Wang： Lagrangian submanifolds in the 6-dimensional nearly K\"ahler manifolds with parallel second fundamental form，Journal of Geometry and Physics, 108 (2016), 21-37.

8. Zejun Hu, Haizhong Li and Luc Vrancken：On four-dimensional Einstein affine hyperspheres, Differential Geometry and Its Applications, 50 (2017), 20-33.

9. Xiuxiu Cheng, Zejun Hu and Marilena Moruz：Classification of locally strongly convex centroaffine hypersurfaces with parallel cubic form, Results in Mathematics, 72 (2017), 419–469.

10. Xiuxiu Cheng, Zejun Hu, Marilena Moruz and Luc Vrancken: On product affine hyperspheres in R^{n+1}, SCIENCE CHINA Mathematics（接受发表）

11. Miroslava Antic, Zejun Hu, Marilena Moruz and Luc Vrancken：P-invariant surfaces in the homogeneous nearly K\"ahler S^3*S^3,（完成待发表）