2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/126180We shall give an explicit pair of birational projective Calabi--Yau threefolds which are rigid, non-homeomorphic, but are connected by projective flat deformation over some connected base scheme.15 pages 7 figures many typos are correctedAlgebraic Geometry14J32; 14D06Connecting certain rigid birational non-homeomorphic Calabi--Yau threefolds via Hilbert schemetext