  In recent years some researchers have explored the use of reinforcement
learning (RL) algorithms as key components in the solution of various natural
language processing tasks. For instance, some of these algorithms leveraging
deep neural learning have found their way into conversational systems. This
paper reviews the state of the art of RL methods for their possible use for
different problems of natural language processing, focusing primarily on
conversational systems, mainly due to their growing relevance. We provide
detailed descriptions of the problems as well as discussions of why RL is
well-suited to solve them. Also, we analyze the advantages and limitations of
these methods. Finally, we elaborate on promising research directions in
natural language processing that might benefit from reinforcement learning.
