2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/66358We reduce the Abundance Conjecture in dimension 4 to the following numerical statement: if the canonical divisor K is nef and has maximal nef dimension, then K is big. From this point of view, we ``classify'' in dimension 2 nef divisors which have maximal nef dimension, but which are not big.LaTex, 14 pagesAlgebraic Geometry14E30; 14J10text