2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/230877We construct a new 20-dimensional family of algebraic hyper-Kaehler fourfolds and prove that they are deformation-equivalent to the second punctual Hilbert scheme of a K3 surface of degree 22.Typos corrected. Connection made with the work of Gritsenko, Hulek, and Sankaran on the Kodaira dimension of moduli spaces of hyper-Kaehler manifolds (arXiv:0802.2078)Algebraic Geometry14J35; 14M15; 14J70text