2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/150237In this paper we discuss some recent results about extremal contractions of complex algebraic varieties. These are proper surjective maps, $ϕ: X\longrightarrow Z$, of normal varieties with connected fibers such that $X$ has mild singularities (in particular $X$ is $Q$-Gorenstein) and the anticanonical divisor of $X$ is $ϕ$ ample. It will appear on the Proceedings of AMS-SRI on Algebraic Geometry, Santa Cruz 1995.AMS-TeX (pspum), 31 pagesAlgebraic Geometry14E30, 14J40 (Primary), 32H02 (Secondary)text