In mathematics, Raynaud's isogeny theorem, proved by Raynaud (1985), relates the Faltings heights of two isogeneous elliptic curves.
References
Raynaud, Michel (1985). "Hauteurs et isogénies" [Heights and isogenies]. In Szpiro, Lucien (ed.). Séminaire sur les pinceaux arithmétiques: la conjecture de Mordell [Seminar on arithmetic pencils: the Mordell conjecture]. Astérisque (in French). Paris: Société Mathématique de France. pp. 199–234. ISSN 0303-1179. MR 0801923. Zbl 1182.14049.