abstract = "The advent of reinforcement learning (RL) in financial
markets is driven by several advantages inherent to
this field of artificial intelligence. In particular,
RL allows to combine the prediction and the portfolio
construction task in one integrated step, thereby
closely aligning the machine learning problem with the
objectives of the investor. At the same time, important
constraints, such as transaction costs, market
liquidity, and the investor degree of risk-aversion,
can be conveniently taken into account. Over the past
two decades, and albeit most attention still being
devoted to supervised learning methods, the RL research
community has made considerable advances in the finance
domain. The present paper draws insights from almost 50
publications, and categorizes them into three main
approaches, i.e. critic-only approach, actor-only
approach, and actor-critic approach. Within each of
these categories, the respective contributions are
summarized and re- viewed along the representation of
the state, the applied reward function, and the action
space of the agent. This cross-sectional perspective
allows us to identify recurring design decisions as
well as potential levers to improve the agent
performance. Finally, the individual strengths and
weaknesses of each approach are discussed, and
directions for future research are pointed out.",
notes = "mention of GP also known as
\cite{RePEc:zbw:iwqwdp:122018}