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Wed, 10. Sep at 15:15
WIAS, Erhard-Schm...
Hibler's time-periodic sea ice model on ℝ²
Abstract
Thu, 11. Sep at 14:00
Weierstrass Insti...
The Latent Variable Proximal Point Method: A New Solver Paradigm for Variational Inequalities, Nonlinear PDEs, and Beyond
Abstract. The Latent Variable Proximal Point (LVPP) method is a novel, geometry-encoding scheme in which the continuous level informs the algorithms, discretization techniques, and implementation. Mathematically speaking, it embeds the problem at hand into a sequence of related saddle-point problems by introducing a structure-preserving transformation between a latent Banach space and the feasible set. LVPP arises at the confluence of information geometry, optimization, and convex analysis through its use of proximal point methods, Legendre functions, and the isomorphisms induced by their gradients. The method yields algorithms with mesh-independent convergence behaviour for obstacle problems, contact, topology optimization, fracture, plasticity, and more; in many cases, for the first time.
Wed, 17. Sep at 16:30
EN 058
Lower bound theorems on the face numbers of polytopes with few vertices
Abstract. We study lower bound theorems for the number of $k$-faces ($1\le k\le d-2$) of a $d$-dimensional polytope $P$ (or \emph{$d$-polytope}) with up to $3d-1$ vertices. Earlier results include the following: Xue (2021) established the case of polytopes with at most $2d$ vertices; Xue (2022) and Pineda-Villavicencio and Yost (2022) independently settled the case of $2d+1$ vertices; and Pineda-Villavicencio, Tritama, and Yost (2024) extended this to $2d+2$ vertices.<br>We present a recent lower bound theorem covering $d$-polytopes with up to $3d-1$ vertices. If $P$ has exactly $d+2$ facets and at least $2d+\ell$ vertices, the lower bound is tight for certain combinations of $d$ and $\ell$. When $P$ has at least $d+3$ facets, the lower bound is always tight, with equality for some $1\le k\le d-2$ only when $P$ has precisely $d+3$ facets. These results confirm a conjecture of Pineda-Villavicencio (2024). <br>We outline the main ideas and methods underlying the proof and describe some minimisers for each number of vertices between $d+2$ and $3d-1$. <br>We conclude with a discussion of what happens beyond $3d-1$ vertices---where the picture becomes more intricate.<br>This is joint work with Jie Wang (Deakin).
Wed, 15. Oct at 14:00
ZIB, Room 2006 (S...
Wed, 15. Oct at 15:15
rooms 405/406
Wed, 22. Oct at 15:15
Library, room 411
Wed, 29. Oct at 16:30
EN 058
Tue, 04. Nov at 11:15
1.023 (BMS Room, ...
Tue, 11. Nov at 11:15
1.023 (BMS Room, ...
Wed, 12. Nov at 15:15
WIAS, Erhard-Schm...
Wed, 26. Nov at 15:15
WIAS, Erhard-Schm...
Tue, 13. Jan at 11:15
1.023 (BMS Room, ...