van Gennip, Yves, Guillen, Nestor, Osting, Braxton and Bertozzi, Andrea L.
(2014)
Mean curvature, threshold dynamics, and phase field theory on finite graphs.
Milan Journal of Mathematics, 82
(1).
pp. 365.
ISSN 14249286
Full text not available from this repository.
Abstract
In the continuum, close connections exist between mean curvature flow, the AllenCahn (AC) partial differential equation, and the MerrimanBenceOsher (MBO) threshold dynamics scheme. Graph analogues of these processes have recently seen a rise in popularity as relaxations of NPcomplete combinatorial problems, which demands deeper theoretical underpinnings of the graph processes. The aim of this paper is to introduce these graph processes in the light of their continuum counterparts, provide some background, prove the first results connecting them, illustrate these processes with examples and identify open questions for future study.
We derive a graph curvature from the graph cut function, the natural graph counterpart of total variation (perimeter). This derivation and the resulting curvature definition differ from those in earlier literature, where the continuum mean curvature is simply discretized, and bears many similarities to the continuum nonlocal curvature or nonlocal means formulation. This new graph curvature is not only relevant for graph MBO dynamics, but also appears in the variational formulation of a discrete time graph mean curvature flow.
We prove estimates showing that the dynamics are trivial for both MBO and AC evolutions if the parameters (the timestep and diffuse interface scale, respectively) are sufficiently small (a phenomenon known as ``freezing'' or ``pinning'') and also that the dynamics for MBO are nontrivial if the time step is large enough. These bounds are in terms of graph quantities such as the spectrum of the graph Laplacian and the graph curvature. Adapting a Lyapunov functional for the continuum MBO scheme to graphs, we prove that the graph MBO scheme converges to a stationary state in a finite number of iterations. Variations on this scheme have recently become popular in the literature as ways to minimize (continuum) nonlocal total variation.
Item Type: 
Article

RIS ID: 
https://nottinghamrepository.worktribe.com/output/1000367 
Additional Information: 
The final publication is available at Springer via http://dx.doi.org/10.1007/s0003201402168 
Keywords: 
spectral graph theory, AllenCahn equation, GinzburgLandau
functional, MerrimanBenceOsher threshold dynamics, graph cut
function, total variation, mean curvature flow, nonlocal mean curvature, gamma convergence, graph coarea formula 
Schools/Departments: 
University of Nottingham, UK > Faculty of Science > School of Mathematical Sciences University of Nottingham, UK > Faculty of Science 
Identification Number: 
https://doi.org/10.1007/s0003201402168 
Depositing User: 
van Gennip, Dr Yves

Date Deposited: 
23 Jun 2014 11:36 
Last Modified: 
04 May 2020 20:18 
URI: 
https://eprints.nottingham.ac.uk/id/eprint/3186 
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