%0 Journal Article %A Fajmon, Břetislav %T Operations, homomorphism and update versus relational database systems %J Communications in Mathematics %D 2000 %P 99-109 %V 08 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/COMIM_2000__8_1_a9/ %G en %F COMIM_2000__8_1_a9