In this paper the method of optimal level solutions, introduced by Cambini and Martein for fractional programming problems [5,·81, is developed in a general framework. In such a framework all the algorithms based on the optimal level solutions approach stated so far in literature can be easily embedded and their properties proved at once.
INTRODUCTIONIn the late 80's and in the 90's a lot of papers were devoted to the development of algorithms to solve a mathematical programming problem by means of the examination of a . suitably defined subset of the feasible region: more precisely, the set of optimal points of a corresponding parametric program is explored instead of the whole feasible region. Cambini and Martein in their pioneering papers [5,8,10], referring in particular to the linear fractional program, called such subset the optimal level solutions set.The known algorithms based on this idea are of simplex like type and, at least in the special cases investigated till now, computationally comparable with the simplex method for linear programs (for computational experiments see [4,16,17,23]). This paper deals with the generalization of the concept of optimal level solutions to a wide class of mathematical programming problems: some general properties of these solutions and of the corresponding optimal value function are stated in sections 2 and 3.The stated properties are essential in order to develop algorithms for thE? solution of the considered programs. The general structure of such algorithms will be discussed in section 4, while in section 5 it will