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A Private and Computationally-Efficient Estimator for Unbounded Gaussians
Proceedings of Thirty Fifth Conference on Learning Theory, PMLR 178:544-572, 2022.
Abstract
We give the first polynomial-time, polynomial-sample, differentially private estimator for the mean and covariance of an arbitrary Gaussian distribution N(μ,Σ) in \Rd. All previous estimators are either nonconstructive, with unbounded running time, or require the user to specify a priori bounds on the parameters μ and Σ. The primary new technical tool in our algorithm is a new differentially private preconditioner that takes samples from an arbitrary Gaussian N(0,Σ) and returns a matrix A such that AΣAT has constant condition number