August 21, 2025 ; 19:30 JST/12:30 CEST : Jun Matsumoto (Science Tokyo) 松本 洵（東京科学大学）
Title: A class of affine maximal surfaces with singularities and its relationship with minimal surface theory
Abstract: A surface in unimodular affine 3-space R^3 whose affine mean curvature vanishes everywhere is called an affine maximal surface. In this talk, I will explain the global theory of affine maximal surfaces with singularities, called affine maximal maps, which were defined by Aledo, Martínez, and Milán in 2009.
We define a new subclass of these surfaces, which we call affine maxfaces. By applying Euclidean minimal surface theory, we show that the ``complete'' affine maxfaces satisfy an Osserman-type inequality, and we provide examples of such surfaces that are related to Euclidean minimal surfaces.
July 17, 2025 ; 20:00 JST/13:00 CEST : Riku Kishida (Science Tokyo) 岸田 陸玖（東京科学大学）
Title: The volume of marginally trapped submanifolds and flat surfaces in 3-dimensional light-cone
Abstract: A space-like submanifold of codimension 2 in a Lorentzian manifold is said to be marginally trapped if its mean curvature vector field is light-like. In this talk, I explain that a marginally trapped submanifold has a locally volume-maximizing property under specific conditions. As a typical example of marginally trapped surface in the 4-dimensional Minkowski spacetime, I also discuss flat surfaces in the 3-dimensional light-cone.
June 26, 2025 ; 20:00 JST/13:00 CEST : Philipp Käse (Kobe University; TU Darmstadt)
Title: A new family of CMC surfaces in homogeneous spaces
Abstract: In 1841 Delaunay characterized surfaces of constant mean curvature H=1 in Euclidean 3-space invariant under rotation. This result was generalized by several authors to screw-motion invariant CMC surfaces in E(k,t), but it turns out that the classification is not complete. In fact, new (embedded) CMC surfaces arise in addition to the Delaunay family. In this talk I would like to talk about these new surfaces and present a complete classification of screw motion CMC surfaces in E(k,t).
June 12, 2025 ; 20:00 JST/13:00 CEST : Yuta Ogata (Kyoto Sangyo University) 緒方 勇太（京都産業大学）
Title: Darboux transformations for curves
Abstract: We introduce the Darboux transformations for smooth and discrete curves. This is related to the linearization of Riccati type equations and we study their monodromy problem. We will show some examples of periodic (closed) Darboux transformations for curves. This is based on the joint work with Joseph Cho and Katrin Leschke.
March 27, 2025; 20:00 JST/12:00 CEST : Udo Hertrich-Jeromin (TU Vienna)
Title: Doubly cGc profiles
Abstract/Info: I plan to talk about a joint project on profile curves that generate two surfaces of revolution of constant Gauss curvature in different space forms. This is joint work with S Bentrifa, M Kokubu and D Polly.