Convergence of diffusion generated motion to motion by mean curvature

We provide a new proof of convergence to motion by mean curvature (MMC) for the Merriman-Bence-Osher thresholding algorithm. The proof is elementary and does not rely on maximum principle for the scheme. The strategy is to construct a natural ansatz of the solution and then estimate the error. The proof thus also provides a convergence rate. Only some weak integrability assumptions of the heat kernel, but not its positivity, is used. Currently the result is proved in the case when smooth and classical solution of MMC exists.