  Future wireless communication networks are expected to fulfill the
unprecedented performance requirements to support our highly digitized and
globally data-driven society. Various technological challenges must be overcome
to achieve our goal. Among many potential technologies, reconfigurable
intelligent surface (RIS) and artificial intelligence (AI) have attracted
extensive attention, thereby leading to a proliferation of studies for
utilizing them in wireless communication systems. The RIS-based wireless
communication frameworks and AI-enabled technologies, two of the promising
technologies for the sixth-generation networks, interact and promote with each
other, striving to collaboratively create a controllable, intelligent,
reconfigurable, and programmable wireless propagation environment. This paper
explores the road to implementing the combination of RIS and AI; specifically,
integrating AI-enabled technologies into RIS-based frameworks for maximizing
the practicality of RIS to facilitate the realization of smart radio
propagation environments, elaborated from shallow to deep insights. We begin
with the basic concept and fundamental characteristics of RIS, followed by the
overview of the research status of RIS. Then, we analyze the inevitable trend
of RIS to be combined with AI. In particular, we focus on recent research about
RIS-based architectures embedded with AI, elucidating from the intelligent
structures and systems of metamaterials to the AI-embedded RIS-assisted
wireless communication systems. Finally, the challenges and potential of the
topic are discussed.
