We show that the axiom of infinity is true in NFU assuming that the number of atoms is less or equal than the number of sets. (C) 1999 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.
Crabbé, M. (1999). L’axiome de l’infini dans NFU. Comptes rendus de l’Académie des sciences - Series I - Mathematics, 329(12), 1033-1035. https://doi.org/10.1016/S0764-4442(00)88469-4 (Original work published 1999)