  Real-time advertising allows advertisers to bid for each impression for a
visiting user. To optimize specific goals such as maximizing revenue and return
on investment (ROI) led by ad placements, advertisers not only need to estimate
the relevance between the ads and user's interests, but most importantly
require a strategic response with respect to other advertisers bidding in the
market. In this paper, we formulate bidding optimization with multi-agent
reinforcement learning. To deal with a large number of advertisers, we propose
a clustering method and assign each cluster with a strategic bidding agent. A
practical Distributed Coordinated Multi-Agent Bidding (DCMAB) has been proposed
and implemented to balance the tradeoff between the competition and cooperation
among advertisers. The empirical study on our industry-scaled real-world data
has demonstrated the effectiveness of our methods. Our results show
cluster-based bidding would largely outperform single-agent and bandit
approaches, and the coordinated bidding achieves better overall objectives than
purely self-interested bidding agents.
