We explore the relationship between R. W. Shephard's input distance fu
nction (''Cost and Production Functions,'' Princeton Univ. Press, Prin
ceton, 1953) and D. G. Luenberger's benefit function (J. Math. Econ. 2
1 (1992a), 461-481). We point out that the latter can be recognized in
a production context as a directional input distance function which c
an exhaustively characterize technologies in both price and input spac
e. D. McFadden's (Cost, revenue, and profit functions, in ''Production
Economics: A Dual Approach to Theory and Applications, ''North-Hollan
d/Elsevier, New York, 1978) composition rules for input sets and input
distance functions are then extended to the directional input distanc
e function. (C) 1996 Academic Press, Inc.