  With the ever increasing number of filed patent applications every year, the
need for effective and efficient systems for managing such tremendous amounts
of data becomes inevitably important. Patent Retrieval (PR) is considered the
pillar of almost all patent analysis tasks. PR is a subfield of Information
Retrieval (IR) which is concerned with developing techniques and methods that
effectively and efficiently retrieve relevant patent documents in response to a
given search request. In this paper we present a comprehensive review on PR
methods and approaches. It is clear that, recent successes and maturity in IR
applications such as Web search cannot be transferred directly to PR without
deliberate domain adaptation and customization. Furthermore, state-of-the-art
performance in automatic PR is still around average in terms of recall. These
observations motivate the need for interactive search tools which provide
cognitive assistance to patent professionals with minimal effort. These tools
must also be developed in hand with patent professionals considering their
practices and expectations. We additionally touch on related tasks to PR such
as patent valuation, litigation, licensing, and highlight potential
opportunities and open directions for computational scientists in these
domains.
