2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/60467We show that diagonal subalgebras and generalized Veronese subrings of a bigraded Koszul algebra are Koszul. We give upper bounds for the regularity of sidediagonal and relative Veronese modules and apply the results to symmetric algebras and Rees rings.13 pagesCommutative Algebra13A99; 13D99text