TABLE OF CONTENTS Chapter written by Sonia CHARDONNEL.
Geography uses data, methods and tools which, used together, can explain the terms and rules of the organization and production of space. To bring to light underlying structures and forms of spatial organization, it is necessary to take into account the process that created these structures; that is why the "space-time" question is very often at the core, implicitly or explicitly, of geographical arguments.
Two main approaches integrating time can be followed. The first approach, which is centered on the research of models of organization and evolution of spatial entities and systems, takes time into account in order to compare and measure the evolution of the spatial structures between different periods. The second, which focuses on the time of individuals, considers space as a variable describing the successive locations of the individual's life path.
In order to illustrate the first category of approach, two examples can be given: urban models and diffusion models.
Urban growth is often studied with the help of models implicitly integrating time; that is the case of the economic models of Alonso [ALO 64] about underlying dynamics of concentric form (inspired by the theory of Von Th nen), where a relation is built between the rent of the land and the distance to downtown. This is also the case with urban ecology models [GRA 79] (concentric, sectorial and polynuclear) where the extension of cities is explained...
