Functional Dependencies
A->C,D. A can uniquly determined a C, C,D can be independently determined by A. if there are single A mapping to multiple C, it doesn’t hold.
1.reflexity:A,B,C->C, A,B,C->A,B
2.aumentation:A->B, A,Z->B,Z
3.transivity:A->B,B->C,A->C