located in rural areas, these businesses may employ most of the local population. As they leave, the local area loses its economic base.) In other cases, the final product is equally as heavy as the raw materials that require transport (i.e. the Material Index is equal to 1). Usually this is a case of some ubiquitous raw material, such as water, being incorporated into the product. This is called the weight-gaining industry. This type of industry might build up near a market or near a raw material source, and as a result might be called a foot-loose industry. Cotton industry is a prominent example of weight-gaining raw material. In a third set of industries, including the heavy chemical industry, the weight of raw materials is less than the weight of the finished product. These industries always grow up near market. Weber's point of optimal transportation is a generalization of the Fermat point problem. In its simplest form, the Fermat problem consists in locating a point D with respect to three points A, B, and C in such a way that the sum of the distances between D and each of the three other points is minimized. As for the Weber triangle problem, it consists in locating a point D with respect to three points A, B, and C in such a way that the sum of the transportation costs between D and each of the three other points is minimized. In 1971, Luc-Normand Tellier found the first direct (non iterative) numerical solution of the Fermat and Weber triangle problems. Long before Von Thünen's contributions, which go back to 1818, the Fermat point problem can be seen as the very beginning of space economy. It was formulated by the famous French mathematician Pierre de Fermat before 1640. As for the Weber triangle problem, which is a generalization of the Fermat triangle problem, it was first formulated by Thomas Simpson in 1750, and popularized by Alfred Weber in 1909. In 1985, in a book entitled Économie spatiale: rationalité économique de l'espace habité, Tellier formulated an all-new problem called the "attraction-repulsion problem", which constitutes a generalization of both the Fermat and Weber problems. In its simplest version, the attraction-repulsion problem consists in locating a point D with respect to three points A1, A2 and R in such a way that the attractive forces exerted by points A1 and A2, and the repulsive force