Ex. 4. (6 pts) For each of the following relation schemas and sets of FD's S: R(A,B,C,D) with FD's ABC, B D, CDA, ADB. b) a) R(A,B,C,D) with FD's AB, BC, C D, DA. Indicate the BCNF violations (if any). Decompose the relations, as necessary, into relations that are in BCNF