2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99733We study geometric transitions for topological strings on compact Calabi-Yau hypersurfaces in toric varieties. Large N duality predicts an equivalence between topological open and closed string theories connected by an extremal transition. We develop new open string enumerative techniques and perform a high precision genus zero test of this conjecture for a certain class of toric extremal transitions. Our approach is based on a) an open string version of Gromov-Witten theory with convex obstruction bundle and b) an extension of Chern-Simons theory treating the framing as a formal variable.88 pages, 14 figures (11 color); v2: minor changes; v3: published versionHigh Energy Physics - TheoryAlgebraic Geometrytext