Semantic Tracklets: An Object-Centric Representation for Visual
  Multi-Agent Reinforcement Learning
  Solving complex real-world tasks, e.g., autonomous fleet control, often
involves a coordinated team of multiple agents which learn strategies from
visual inputs via reinforcement learning. Many existing multi-agent
reinforcement learning (MARL) algorithms however don't scale to environments
where agents operate on visual inputs. To address this issue, algorithmically,
recent works have focused on non-stationarity and exploration. In contrast, we
study whether scalability can also be achieved via a disentangled
representation. For this, we explicitly construct an object-centric
intermediate representation to characterize the states of an environment, which
we refer to as `semantic tracklets.' We evaluate `semantic tracklets' on the
visual multi-agent particle environment (VMPE) and on the challenging visual
multi-agent GFootball environment. `Semantic tracklets' consistently outperform
baselines on VMPE, and achieve a +2.4 higher score difference than baselines on
GFootball. Notably, this method is the first to successfully learn a strategy
for five players in the GFootball environment using only visual data.
