A decentralized prediction-correction method for networked time-varying convex optimization

Abstract

We study networked unconstrained convex optimization problems where the objective function changes continuously in time. We propose a decentralized algorithm (DePCoT) with a discrete time-sampling scheme to find and track the solution trajectory based on prediction and gradient-based correction steps, while sampling the problem data at a constant sampling period h. Under suitable conditions and for limited sampling periods, we establish that the asymptotic error bound behaves as O(h2), which outperforms the state of the art existing error bound of O(h) for correction-only methods. The key contributions are the prediction step and a decentralized method to approximate the inverse of the Hessian of the cost function in a decentralized way, which yields quantifiable trade-offs between communication and accuracy.