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Accession Number ADA581612
Title Mean Curvature, Threshold Dynamics, and Phase Field Theory on Finite Graphs.
Publication Date Jun 2013
Media Count 58p
Personal Author A. L. Bertozzi B. Osting N. Guillen Y. Gennip
Abstract In the continuum, close connections exist between mean curvature flow, the Allen-Cahn (AC) partial differential equation, and the Merriman-Bence- Osher (MBO) threshold dynamics scheme. Graph analogues of these processes have recently seen a rise in popularity as relaxations of NP-complete 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 time-step 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.
Keywords Allen-cahn equation
Convergence
Curvature
Dynamics
Equations
Finite graphs
Flow
Gamma convergence
Ginzburg-landau functional
Graph coarea formula
Graph cut function
Graphs
Lyapunov functions
Mean curvature
Mean curvature flow
Merriman-bence-osher threshold dynamics
Nonlocal mean curvature
Phase field theory
Spectral graph theory
Theory
Threshold dynamics
Threshold effects
Total variation

 
Source Agency Non Paid ADAS
NTIS Subject Category 72B - Algebra, Analysis, Geometry, & Mathematical Logic
Corporate Author California Univ., Los Angeles. Dept. of Mathematics.
Document Type Technical report
Title Note Research paper.
NTIS Issue Number 1325
Contract Number N/A

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