 Consider now, for the sake of concreteness, two Newtonian worlds which differ by either a static or a kinematic Leibniz shift: that is, constant translations or velocity boosts of the material content of the universe (see the companion entry on  absolute and relational space and motion: classical theories,  for further discussion of such shifts). These two worlds will be represented by distinct curves in configuration space. However, given a configuration space, one can construct a ‘reduced’ configuration space, in which certain such histories are mathematically identified, or ‘quotiented’, such that they are mapped to the same unique history in reduced configuration space. Specifically, proponents of this approach define two such reduced configuration spaces: