(term proposed by B. Mandelbrot) In mathematics, a fractal is a geometrical object such that the same properties are showing at different scales. There is thus a hierarchically organised structure, which follows a well-defined hyperbolic law, either determinist (regular fractal) or stochastic (random fractal): n(e) = e -D where e is the measure interval(variable parameter […]
Friction of distance is an expression that is sometimes used in order to designate the attenuating effect of distance on intensity of interactions between places, or else, in gravity models, the parameter measuring this gradient.
Is called gradient the variation of intensity of a phenomenon per unit of distance between a place and a given centre (or axis). It is the case for example with density gradients which develop around a city centre, gradients of population, facilities, shops, services, gradients of land prices, etc. gradients of population which appear on […]
The gravity model is aimed at formalising, studying and predicting geography of flows or interactions. The distribution of interactions in a set of places depends on their configuration, i.e. the force of attraction of each one and the difficulty of communication between them. The model has first been formulated in analogy with Newton’s law of […]
The notion of hierarchy is used with two distinct meanings. It is a social, political or administrative organisation in levels where each element belonging to a level is strictly subordinated to an element of upper level. The higher it is gone in the order of power or domination, the fewer elements are comprised in each […]
The notion of homogeneity describes the greater or lesser equality of values of a variable or of a combination of features in a geographical set. Parameters of statistical dispersion, such as variance, measure its converse, heterogeneity. The homogeneous region is a type of region defined by a greater similarity among the units that compose it […]
An interaction is a reciprocal action (retroaction) between two or more actors or places in a system. All exchanges (of matter, persons, information…), for example at individual level between producer and customer, between partners, or at aggregate level between cities or regions (these are the spatial interactions), are interactions as far as they generate interdependent […]
A law is a general formula expressing a constant or usual relation between phenomena; laws brought to the fore by science of nature apply in physical geography; in human geography, laws are the necessary reference for the explanation, whether the object under study conforms itself to it or deviates from it (notions of exception, of […]
The term designates in the first place the position of an object on the earth surface by means of an explicit reference system, which is often the system of geographical coordinates. Those coordinates, essential for locating the object, represent the geometrical part of the G.I.S. It will sometimes be said that they are used to […]
Area in which consumers of goods and services produced by a firm are recruited. In Christaller’s and Lösch’s theories, the market area corresponds to the area in which the transport cost tA, added to the price c of the good produced in A, does not surpass the price p that the consumer is willing to […]