The Neron-Severi group of a proper seminormal complex variety
  We prove a Lefschetz (1,1)-Theorem for proper seminormal varieties over the complex numbers. The proof is a non-trivial geometric argument applied to the isogeny class of the Lefschetz 1-motive associated to the mixed Hodge structure on H^2. 
L. Barbieri-Viale, A. Rosenschon, V. Srinivas