2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54526We review some examples of heterotic/type II string duality which shed light on the infrared dynamics of string compactifications with N=2 and N=1 supersymmetry in four dimensions.13 pages, latex. Talk presented at the workshop ``Frontiers in Quantum Field Theory'' in honor of K. Kikkawa's 60th birthday, Osaka, Japan, December 1995High Energy Physics - Theorytext