TY - JOUR TI - On the interaction between closure operations and choice functions with applications to relational databases T3 - Acta cybernetica AU - Demetrovics János PY - 1992 LA - English SN - 0324-721X UR - http://acta.bibl.u-szeged.hu/12501/1/cybernetica_010_numb_003_129-139.pdf ER -