Distributed Online Convex Optimization with Adversarial Constraints: Reduced Cumulative Constraint Violation Bounds under Slater's Condition
This paper considers distributed online convex optimization with adversarial constraints. In this setting, a network of agents makes decisions at each round, and then only a portion of the loss function and a coordinate block of the constraint function are privately revealed to each agent. The loss and constraint functions are convex and can vary arbitrarily across rounds. The agents collaborate to minimize network regret and cumulative constraint violation. A novel distributed online algorithm is proposed and it achieves an šŖ(T^max{c,1-c}) network regret bound and an šŖ(T^1-c/2) network cumulative constraint violation bound, where T is the number of rounds and cā(0,1) is a user-defined trade-off parameter. When Slater's condition holds (i.e, there is a point that strictly satisfies the inequality constraints), the network cumulative constraint violation bound is reduced to šŖ(T^1-c). Moreover, if the loss functions are strongly convex, then the network regret bound is reduced to šŖ(log(T)), and the network cumulative constraint violation bound is reduced to šŖ(ā(log(T)T)) and šŖ(log(T)) without and with Slater's condition, respectively. To the best of our knowledge, this paper is the first to achieve reduced (network) cumulative constraint violation bounds for (distributed) online convex optimization with adversarial constraints under Slater's condition. Finally, the theoretical results are verified through numerical simulations.
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