2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/174447We derive a cut-and-paste surgery formula of Seiberg--Witten invariants for negative definite plumbed rational homology 3-spheres. It is similar to (and motivated by) Okuma's recursion formula [arXiv:math.AG/0610464, 4.5] targeting analytic invariants of splice quotient singularities. The two formulas combined provide automatically a proof of the equivariant version [arXiv:math.AG/0310084, 5.2(b)] of the `Seiberg--Witten invariant conjecture' [arXiv:math.AG/0111298] for these singularities.17 pages, 4 figures, accepted by Journal für die reine und angewandte Mathematik. Minor improvements suggested by refereeGeometric TopologyAlgebraic Geometry57M27, 57R57; 32C35, 32S05, 32S25, 32S45text