Critical SK autocorrelation processes and dynamics across the temperature transition
The following describes the scope of the Lean formalization related to the following accompanying paper(s):
Scope
For every fixed inverse temperature 0<β<1, the formalization proves a dimension-independent Poincaré inequality for the zero-field Gaussian Sherrington–Kirkpatrick model with probability tending to one over the disorder. Equivalently, the unscaled single-site heat-bath spectral gap stays bounded away from zero. For dynamics that choose one site uniformly at each discrete step, the spectral gap is at least 1/(Cn) with probability tending to one, for a constant C depending on β.
The formalized supporting result proves ratio cutoff for discrete single-site heat-bath dynamics in the zero-field Gaussian Sherrington–Kirkpatrick model for 0≤β<1/2. For every 0<ε<1/2 and η>0, the probability over the disorder that tmix(ε)/tmix(1−ε)>1+η tends to zero as n→∞. The denominator is positive for all sufficiently large sizes.
The paper's full range β<1, explicit cutoff location, and continuous-time conclusion are outside this selected statement.
At criticality in the zero-field Sherrington–Kirkpatrick model, the formalization proves that for every fixed ε>0, the continuous-time mixing time lies between n2/3−ε and eεn, and the discrete-time mixing count lies between n5/3−ε and eεn, with probability tending to one over the Gaussian disorder. The disorder has independent off-diagonal entries of variance 1/n. Continuous updates have rate one per site; discrete time counts uniformly chosen single-site update attempts. Mixing is worst-start total variation at threshold 1/4, with holding allowed.
For deterministic times tn=o(n2/3) or update counts kn=o(n5/3), the Gibbs mass of realized starting states still farther than 1/4 from equilibrium tends to one in probability. For every deterministic positive sequence Mn→∞, the covariance operator norm and the linear Rayleigh supremum, using the unscaled heat-bath Dirichlet form, both lie between n2/3/Mn and Mnn2/3 with probability tending to one. The covariance result does not give an upper bound for the full inverse spectral gap.
The formalization proves a stretched-exponential mixing obstruction for the zero-field Sherrington–Kirkpatrick model at every fixed inverse temperature β>1. At time exp(n1/10000), the expected Gibbs mass of initial configurations whose total-variation distance from equilibrium exceeds 1/4 tends to one. Since this mass lies in [0,1], it also tends to one in probability over the disorder.
The result covers both rate-one-per-site continuous-time heat-bath dynamics and the same stated number of discrete update attempts.
Comparator links