“…This idea dates back at least to Barbut (1959), Kemeny (1959), Kemeny and Snell (1962) and Slater (1961). Although it raises fascinating deep combinatorial questions and difficult algorithmic problems (see Barthélémy, Guénoche and Hudry, 1989;Monjardet, 1981, 1988;Bermond, 1972;Charon-Fournier, Germa and Hudry, 1992;Charon, Hudry and Woirgard, 1996;Hudry, 1989;Monjardet, 1990), this line of research raises other difficulties. As argued in Perny (1992) and Roy and Bouyssou (1993), -the choice of the distance function should be analyzed with care as soon as one leaves the, easy, case of a distance between tournament and linear orders (see, e.g.…”