“…2 1 A great many papers have addressed this issue, including Leontief (1940), Edwards (1950), Silberberg (1970), Greenhut and Ohta (1976), Smith and Formby (1981), Schmalensee (1981), Varian (1985), Shih, Mai and Liu (1988), Cheung and Wang (1994) and, more recently, Cowan (2007), Aguirre, Cowan and Vickers (2010) (ACV) and Cowan (2012). 2 Neither the "adjusted concavity" criterion (Robinson, 1933, Cheung andWang, 1994), nor the "slope ratio" criterion (Edwards, 1950), nor the "mean-value theorem" criterion (Shih, Mai and Liu, 1988), can be applied to illustrate that price discrimination increases total output with constant elasticity demand.…”