RT Journal Article T1 First-Order Singular and Discontinuous Differential Equations A1 Biles, Daniel C. A1 López Pouso, Rodrigo K1 Weak Solution K1 Extremal Solution K1 Countable Family K1 Great Solution K1 Null Measure AB We use subfunctions and superfunctions to derive sufficient conditions for the existence of extremal solutions to initial value problems for ordinary differential equations with discontinuous and singular nonlinearities. PB SpringerOpen SN 1687-2762 YR 2009 FD 2009 LK http://hdl.handle.net/10347/22855 UL http://hdl.handle.net/10347/22855 LA eng NO Biles, D., López Pouso, R. First-Order Singular and Discontinuous Differential Equations. Bound Value Probl 2009, 507671 (2009). https://doi.org/10.1155/2009/507671 NO The research of Rodrigo Lopez Pouso is partially supported by Ministerio de Educaci ´ on´y Ciencia, Spain, Project MTM2007-61724, and by Xunta de Galicia, Spain, ProjectPGIDIT06PXIB207023PR DS Minerva RD 24 abr 2026