  Do cities have just one or several centers? Studies performing radial or
monocentric analyses of cities are usually criticised by researchers stating
that cities are actually polycentric, and this has been well known for a long
time. Reversely, when cities are studied independently of any center, other
researchers will wonder how the variables of interest evolve with the distance
to the center, because this distance is known to be a major determinant at the
intra-urban scale. Both monocentric and polycentric formalisms have been
introduced centuries (respectively, decades) ago for the study of urban areas,
and used both on the empirical and the theoretical side in different
disciplines (economics, geography, complex systems, physics...). The present
work performs a synthesis of both viewpoints on cities, regarding their use in
the literature, and explores with data on European urban areas how some cities
considered to be the most polycentric in Europe compare to more standard cities
when studied through a combination of radial analysis and scaling laws.
