Abstract:
We consider the problem where NN agents collaboratively interact with an instance of a stochastic KK arm bandit problem for K≫NK≫N. The agents aim to simultaneously minimize the cumulative regret over all the agents for a total of TT time steps, the number of communication rounds, and the number of bits in each communication round. We present Limited Communication Collaboration - Upper Confidence Bound (LCC-UCB), a doubling-epoch based algorithm where each agent communicates only after the end of the epoch and shares the index of the best arm it knows. With our algorithm, LCC-UCB, each agent enjoys a regret of ˜O(√(K/N+N)T)~O(√(K/N+N)T), communicates for O(logT)O(logT) steps and broadcasts O(logK)O(logK) bits in each communication step. We extend the work to sparse graphs with maximum degree KGKG and diameter DD to propose LCC-UCB-GRAPH which enjoys a regret bound of ˜O(D√(K/N+KG)DT)~O(D√(K/N+KG)DT). Finally, we empirically show that the LCC-UCB and the LCC-UCB-GRAPH algorithms perform well and outperform strategies that communicate through a central node.
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