使用Armstrong Axiom找到F +
R = {A,B,C,D}
功能依赖性= {A} - > {B},{B,C} - > {d}
F+ = {A} --> {A,B} --> {B,C} --> {C,D} --> {D}
Derived from above using reflexivity:
{A} --> {B}, {A,B} --> {B}, {A,D} --> {B,D}, {A,C} --> {B,C}, {A,C,D} --> {B,C}
Derived from above using augmentation:
{A} --> {A,B}, {A,B} --> {A,B, A,D} --> {A,B,D}, {A,C} --> {A,B,C}, {A,C,D} --> {A,B,C,D}
{B,C} --> {D}, {A,C} --> {D} (transitivity), {A,C} --> {A,B,C,D} (union rule)
Derived from above using augmentation:
{A,B,C} --> {A,D}, {A,B,C} --> {B,D}
我试图了解如何推导出F + 所以我已经添加了我如何得出它们。
但我不确定他们是否正确。
我感觉我错过了{B,C}的某些部分 - >关闭内部{D}。