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MVD and lossless join decomposition
Let X, Y be sets of attributes of R.
- X Y means that for all instances r of R:
(t1, t2 r : t1[X]=t2[X] :
(t3 r : t3[X]=t1[X] : t3[Y]=t1[Y] t3[R-Y]=t2[R-Y]))
- A decomposition of R into (X,Y), (X,R-Y) is a lossless-join decomposition if and only if
X Y holds in R
Notes: