Generalized Convexity of Some Classes of Fractional Functions

Economic applications are often characterized by maximizing the efficiency of an economic system. This leads to optimization problems whose objective function is a ratio. Examples include maximization of productivity, maximization of return on investment, maximization of return/risk, minimization of cost/time. Linear fractional and generalized fractional problems may be found in different fields such as data envelopment analysis, tax programming, risk and portfolio theory, logistics and location theory (see for instance [14, 15, 66, 67, 166, 214]). The interest in studying fractional problems is confirmed in the extensive survey (with twelve hundred entries) which appeared in [256]; another updated survey may be found in [114].