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Optical flow is a powerful tool for the study and analysis of motion in a sequence of images. In this article we study a Horn-Schunck type spatio-temporal regularization functional for image sequences that have a non-Euclidean, time varying…

Numerical Analysis · Mathematics 2014-10-02 Martin Bauer , Markus Grasmair , Clemens Kirisits

Using techniques of optimal transportation and gradient flows in metric spaces, we extend the notion of Riemannian Curvature Dimension condition $RCD(K,\infty)$ introduced (in case the reference measure is finite) by Giuseppe Savare', the…

Differential Geometry · Mathematics 2019-05-08 Luigi Ambrosio , Nicola Gigli , Andrea Mondino , Tapio Rajala

Bence-Merriman-Osher algorithm computes numerically mean curvature flow via solutions of heat equation iteratively initialized at the end of each short time interval. Inspired by the convergence proof of Evans of this algorithm where he…

Analysis of PDEs · Mathematics 2016-03-04 Emre Baspinar , Giovanna Citti

The curvature discussed in this paper is a rather far going generalization of the Riemannian sectional curvature. We define it for a wide class of optimal control problems: a unified framework including geometric structures such as…

Differential Geometry · Mathematics 2018-11-30 Andrei Agrachev , Davide Barilari , Luca Rizzi

In this paper we study the generalized mean curvature flow of sets in the sub-Riemannian geometry of Carnot groups. We extend to our context the level sets method and the weak (viscosity) solutions introduced in the Euclidean setting by…

Analysis of PDEs · Mathematics 2008-08-27 Luca Capogna , Giovanna Citti

Considering Riemannian submersions, we find necessary and sufficient conditions for when sub-Riemannian normal geodesics project to curves of constant first geodesic curvature or constant first and vanishing second geodesic curvatures. We…

Differential Geometry · Mathematics 2017-07-18 Mauricio Godoy Molina , Erlend Grong , Irina Markina

We define a notion of mean curvature flow with surgery for two-dimensional surfaces in $\mathbb{R}^3$ with positive mean curvature. Our construction relies on the earlier work of Huisken and Sinestrari in the higher dimensional case. One of…

Differential Geometry · Mathematics 2015-09-01 S. Brendle , G. Huisken

Diffusion models are recent state-of-the-art methods for image generation and likelihood estimation. In this work, we generalize continuous-time diffusion models to arbitrary Riemannian manifolds and derive a variational framework for…

Machine Learning · Computer Science 2022-08-18 Chin-Wei Huang , Milad Aghajohari , Avishek Joey Bose , Prakash Panangaden , Aaron Courville

Regularized optimal mass transport (rOMT) problem adds a diffusion term to the continuity equation in the original dynamic formulation of the optimal mass transport (OMT) problem proposed by Benamou and Brenier. We show that the rOMT model…

Numerical Analysis · Mathematics 2022-01-20 Xinan Chen , Anh Phong Tran , Rena Elkin , Helene Benveniste , Allen R. Tannenbaum

We present a synthetic notion of scalar curvature (and its integral) for Riemannian manifolds and metric measure spaces, defined in terms of the initial slope of a Gaussian (double) integral. We explicitly calculate the integral scalar…

Differential Geometry · Mathematics 2026-03-20 Marco Flaim , Erik Hupp , Karl-Theodor Sturm

The mean curvature flow describes the parabolic deformation of embedded branes in Riemannian geometry driven by their extrinsic mean curvature vector, which is typically associated to surface tension forces. It is the gradient flow of the…

High Energy Physics - Theory · Physics 2009-11-13 I. Bakas , C. Sourdis

We investigate the compact submanifolds in Riemannian space forms of nonnegative sectional curvature that satisfy a lower bound on the Ricci curvature, that bound depending solely on the length of the mean curvature vector of the immersion.…

Differential Geometry · Mathematics 2023-11-06 Marcos Dajczer , Theodoros Vlachos

Ricci-Curbastro established necessary and sufficient conditions for a Riemannian metric on a surface to be the first fundamental form of a minimal immersion of that surface into the Euclidean space. We revisit certain developments arising…

Differential Geometry · Mathematics 2024-01-18 Lucas Ambrozio

We consider (smooth) solutions of the mean curvature flow of graphs over bounded domains in a Lie group free up to step two (and not necessarily nilpotent), endowed with a one parameter family of Riemannian metrics $\sigma_\e$ collapsing to…

Analysis of PDEs · Mathematics 2015-02-04 Luca Capogna , Giovanna Citti , Maria Manfredini

A comparison theorem for the isoperimetric profile on the universal cover of surfaces evolving by normalised Ricci flow is proven. For any initial metric, a model comparison is constructed that initially lies below the profile of the…

Differential Geometry · Mathematics 2014-04-24 Paul Bryan

In this paper, we observe a set of functionals of metrics which are all decrease under the Calabi flow and have uniform lower bound along the flow, which give rise to a set of integral estimates on the curvature flow. Using these estimates,…

Differential Geometry · Mathematics 2007-05-23 Xiuxiong Chen

Let $(M^n,g_0)$ and $(\bar{M}^{n+1},\bar{g})$ be complete Riemannian manifolds with $|\bar{\nabla}^k\bar{Rm}|\le \bar{C}$ for $k \le 2$, and suppose there is an isometric immersion $F_0: M^n \rightarrow \bar{M}^{n+1}$ with bounded second…

Differential Geometry · Mathematics 2011-04-29 Hong Huang

In this paper, we establish, for the first time, upper bounds of the Ricci--curvature for Riemannian submersions along the vertical distribution as well as along both the vertical and horizontal distributions. We derive their general forms…

Differential Geometry · Mathematics 2026-03-24 Ravindra Singh

ECG-gated cine imaging in breath-hold enables high-quality diagnostics in most patients, arrhythmia and inability to hold breath, however, can severely corrupt outcomes. Real-time cardiac MRI in free-breathing leverages robust and faster…

Image compression technology eliminates redundant information to enable efficient transmission and storage of images, serving both machine vision and human visual perception. For years, image coding focused on human perception has been…

Computer Vision and Pattern Recognition · Computer Science 2025-03-25 Takahiro Shindo , Yui Tatsumi , Taiju Watanabe , Hiroshi Watanabe