The relation schemas R1 and R2 form a Lossless join decomposition of R if
and only if:
(a) R1⋂R2→(R1-R2)
(b) R1→R2
(c) R1⋂R2→(R2-R1)
(d) R2→R1⋂R2
(A) (a) and (b) happens (B) (a) and (d) happens
(C) (a) and (c) happens (D) (b) and (c) happens
and only if:
(a) R1⋂R2→(R1-R2)
(b) R1→R2
(c) R1⋂R2→(R2-R1)
(d) R2→R1⋂R2
(A) (a) and (b) happens (B) (a) and (d) happens
(C) (a) and (c) happens (D) (b) and (c) happens