Ce modele est principalement utilise en analyse input-output: A represente alors les echanges interindustriels de l'annee de base, u et v les consommations intermediaires totales par produit et par branche de l'annee de projection; plus generalement on peut appliquer cette methode pour desagreger des projections globales de flux positifs (importations par pays et produit, flux de transports . . ) lorsque l'on suppose une certaine stabilite structurelle. Diverses interpretations economiques des coefficients r, et s1 (qui sont en fait strictement positifs puisque u, et v; le sont aussi) ont ete avancees;1 notons toutefois que les grandeurs absolues de r et s n'ont pas de signification intrinseque, car si (r, s) est

[This paper models the dynamics of the earnings distribution among successive generations of workers as a stochastic process. The process arises from the random assignment of abilities to individuals by nature, together with the utility maximizing bequest decisions of their parents. A salient feature of the model is that parents cannot borrow to make human capital investments in their offspring. Consequently the allocation of training resources among the young people of any generation depends upon the distribution of earnings among their parents. This implies in turn that the often noted conflict between egalitarian redistributive policies and economic efficiency is mitigated. A number of formal results are proven which illustrate this fact.]

Let Y=(Y 1 ,Y 2 , .Yn) -0 be an income distribution pattern ton-"income receiving units" which may be n-persons, n-farnilies, n-states of the same country or n-countries.Abstractly, a fiscal program is a course of action, undertaken by social conseasus, under which portions of the incomes of certain receiving units are transferred to other receiving units to render the income distribution more equitable.The most familiar example of such a fiscal program is the collection of taxes from individuals (or individual families) with the revenue being paid out as.welfare payments by the government.As another example, the Federal government may collect taxes from the states only to give some of the revenue back to the states under a "revenue sharing" program.An international consortium or the World Bank may work out a formula under which contributions will be solicited from the wealthy countries or "donors" to provide foreign aid or make concessionary loans to the poor countries.This paper is concerned with the principles governing the design of such equity oriented fiscal programs.The first general principle concerns the "rationality" of the fiscal program.Suppose the income level of "i" is higher that that of "j".On the one hand, a principle of "minimally progressive" suggests that, in case "i" and "j" are taxpayers, "i" should pay no less taxes than "j" and, in case "i" and "j" are recipients of welfare payments "i" should receive no more than "j".On the other hand, a principle of "incentive perservation" suggests that the disposable income of "i" should be no less than that of "j"--i.e. the fiscal program clearly should not reverse their relative income ranks in order to preserve the incentive for the individuals .,. ..