Title
Policy Regret in Repeated Games.
Abstract
The notion of policy regret in online learning is a well defined performance measure for the common scenario of adaptive adversaries, which more traditional quantities such as external regret do not take into account. We revisit the notion of policy regret and first show that there are online learning settings in which policy regret and external regret are incompatible: any sequence of play that achieves a favorable regret with respect to one definition must do poorly with respect to the other. We then focus on the game-theoretic setting where the adversary is a self-interested agent. In that setting, we show that external regret and policy regret are not in conflict and, in fact, that a wide class of algorithms can ensure a favorable regret with respect to both definitions, so long as the adversary is also using such an algorithm. We also show that the sequence of play of no-policy regret algorithms converges to a policy equilibrium, a new notion of equilibrium that we introduce. Relating this back to external regret, we show that coarse correlated equilibria, which no-external regret players converge to, are a strict subset of policy equilibria. Thus, in game-theoretic settings, every sequence of play with no external regret also admits no policy regret, but the converse does not hold.
Year
Venue
Keywords
2018
ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS 31 (NIPS 2018)
online learning,repeated games,strict subset
DocType
Volume
ISSN
Conference
31
1049-5258
Citations 
PageRank 
References 
0
0.34
0
Authors
5
Name
Order
Citations
PageRank
R. Arora148935.97
Michael Dinitz218322.53
Teodor Marinov373.54
Mehryar Mohri44502448.21
Marinov, Teodor Vanislavov500.34