A minimal interpretation of general relativistic spacetime geometry
pp. 71-82
in: Ulrich Majer, Heinz-Jürgen Schmidt (eds), Reflections on spacetime, Berlin, Springer, 1995Abstract
A mathematical theory usually admits of various equivalent formulations. It is not only possible to choose different sets of axioms but also the decision of what is considered as a basic concept and what as a derived one is, to some extent, optional.