In mathematics, the Manin–Drinfeld theorem, proved by Manin (1972) and Drinfeld (1973), states that the difference of two cusps of a modular curve has finite order in the Jacobian variety.
References Drinfeld, V. G. (1973), "Two theorems on modular curves", Akademija Nauk SSSR. Funkcionalnyi Analiz i ego Priloženija, 7 (2): 83–84, ISSN 0374-1990, MR 0318157 Manin, Ju. I. (1972), "Parabolic points and zeta functions of modular curves", Izvestiya Akademii Nauk SSSR. Seriya Matematicheskaya, 36 (1): 19–66, Bibcode:1972IzMat...6...19M, doi:10.1070/IM1972v006n01ABEH001867, ISSN 0373-2436, MR 0314846