2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148314We review recent work which has significantly sharpened our geometric understanding and interpretation of the moduli space of certain $N$=2 superconformal field theories. This has resolved some important issues in mirror symmetry and has also established that string theory admits physically smooth processes which can result in a change in topology of the spatial universe.21 pages with 5 figures, harvmac and epsf. Talk delivered by Greene at STRINGS'93 Conference, Berkeley (reference added)High Energy Physics - TheoryAlgebraic Geometrytext