... of finding this family is presented in this paper.Torn tiit. Trong bai nay, chung t6i trinh bay ho cu'c dai ciia mqt so·do quan h~.1. DEFINITIONS AND PRELIMINARY RESULTSThe relational ... Database Syst.4 (1) (1979) 30-59.[3] Beeri C.,DowdM., Fagin R., Staman R., On the structure of Armstrong relations for functionaldependencies,J. ACM31(1) (1984) 30-46.[4] Bekessy A., DemetrovicsJ.,Contribution ... of finding the familyM(s) is exponential in the number if attributes.REFERENCES'[1] Armstrong W. W., Dependency structures of database relationships,Information Processing,Holland Publ....