Result of the concentration on a limited space of constructions, activities or population. « Population agglomérée » (agglomerated population) (France) : fraction of the population of a municipality living in groups of dwellings separated from each other by less than 200 meters and comprising at least 50 inhabitants (as opposite to « population dispersée » […]
– Process of grouping of persons or activities together in a same place or in an area of limited size. Settlement nodes develop through aggregation of migrants, cities through aggregation of houses or even of urban municipalities when speaking about agglomerations. Services and facilities of a same range aggregate to form a same functional level: […]
Area polarised by a centre, for a set of relations (influence area of a city) or a category of relations (area of cultural or commercial influence, trading area). The notion of influence is difficult to specify. It is measured on basis of frequencies (or probabilities) of travels made by inhabitants of the periphery toward the […]
(from Latin attrahere “to pull towards oneself”) From observation of flows between places, is deducted by analogy the existence of a force of attraction exerted by attributes of a place (site, resources, mass,…) on actors of another place. Attractiveness is a measure of the force of attraction of a place, generally function of the sum […]
Correlation of a variable with itself, whenever considering observations with a gap in time (temporal autocorrelation) or in space (spatial autocorrelation). If presence of a quality in part of a territory makes its presence in neighbouring areas more or less probable, there exists a contiguity effect in the spatial structure, the phenomenon shows spatial autocorrelation; […]
Set of proposals logically deduced from a few non-demonstrable principles, and which, according to some, may form a basis for geographical analysis. Several types of axiomatics have been proposed : – a geometric axiomatics defining geographical space as a set of places identified by coordinates, separated by a distance and endowed with attributes (Béguin, Thisse, […]
Obstacle to the extension of a diffusion process, which thus often acts as a limit between two geographical subsets. A barrier may be physical (mountain, ocean, river), linguistic (border), social or cultural (inequality in access to information, religious resistances, taboos etc…)
By analogy with the physico-chemical theory of dissipative structures, or with synergetics: in a dynamic system, qualitative change of structure which may be generated by an amplification of a small internal fluctuation or by an external perturbation, when the system is in an unstable state. Bifurcations are theoretically unpredictable, they drive the system toward a […]
Mathematical theory developed by R. Thom in order to formalise the behaviour of systems where the continuous change of value of a parameter is susceptible to locally introduce discontinuities in the evolution of state variables. These ruptures have been rigorously described and classified by means of a number of state variables lower or equal to […]
The central places theory was conceived, primarily by W. Christaller and A. Lösch, in order to explain size and number of cities and their spacing in a territory. It relies on a definition of city that considers it essentially as a distribution centre of goods and services to a scattered population, and on optimisation principles […]