Given a target function
H to minimize or a target Gibbs distribution
πβ0∝e−βH to sample from in the low temperature, in
this paper we propose and analyze Langevin Monte Carlo (LMC) algorithms that
run on an alternative landscape as specified by
Hβ,c,1f and target a
modified Gibbs distribution $\pi^f_{\beta,c,1} \propto e^{-\beta
H^f_{\beta,c,1}}
,wherethelandscapeofH^f_{\beta,c,1}$ is a transformed
version of that of
H which depends on the parameters
f,β and
c. While
the original Log-Sobolev constant affiliated with
πβ0 exhibits
exponential dependence on both
β and the energy barrier
M in the low
temperature regime, with appropriate tuning of these parameters and subject to
assumptions on
H, we prove that the energy barrier of the transformed
landscape is reduced which consequently leads to polynomial dependence on both
β and
M in the modified Log-Sobolev constant associated with
πβ,c,1f. This yield improved total variation mixing time bounds and
improved convergence toward a global minimum of
H. We stress that the
technique developed in this paper is not only limited to LMC and is broadly
applicable to other gradient-based optimization or sampling algorithms.