2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/70014In this article we studied Nielsen coincidence theory for maps between manifolds of same dimension without hypotheses on orientation. We use the definition of semi-index of a class, we review the definition of defective classes and study the appearance of defective root classes. We proof a semi-index product formula type for lifting maps and we presented conditions such that defective coincidence classes are the only essencial classes.9 pages, 1 figureAlgebraic Topology55M20text