第1个回答 2013-06-29
Solution:
1.X→Y (given)
2.W→Z (given)
3.X→Y∩W (by joint dependence and 1)
4.W-Y→W-Y (self-determination)
5.X∪(W-Y)→(Y∩W)∪(W-Y) =W
(by composition, 3, 4)
6.X∪(W-Y)→W (simplifying 5)
7.X∪(W-Y)→Z (by transitivity, 6, 2)
8. X∪(W-Y)→Y∪Z (by composition, 1, 7)