Resumen: We prove that if (C, 0) is a reduced curve germ on a rational surface singularity (X, 0) then its delta invariant can be recovered by a concrete expression associated with the embedded topological type of the pair C X. Furthermore, we also identify it with another (a priori) embedded analytic invariant, which is motivated by the theory of adjoint ideals. Finally, we connect our formulae with the local correction term at singular points of the global Riemann-Roch formula, valid for projective normal surfaces, introduced by Blache. Idioma: Inglés DOI: 10.1142/S0219199721500528 Año: 2022 Publicado en: Communications in Contemporary Mathematics 24, 7 (2022), 2150052 [23 pp.] ISSN: 0219-1997 Factor impacto JCR: 1.6 (2022) Categ. JCR: MATHEMATICS rank: 62 / 329 = 0.188 (2022) - Q1 - T1 Categ. JCR: MATHEMATICS, APPLIED rank: 105 / 267 = 0.393 (2022) - Q2 - T2 Factor impacto CITESCORE: 2.9 - Mathematics (Q2)