国际空间研究组织 | ISRO CS 2011 |问题 53
在功能依赖阿姆斯壮推理规则是指
(A)自反性、增强和分解
(B)传递性、扩充性和反身性
(C)增强、传递性、自反性和分解
(D)自反性、传递性和分解答案:(乙)
解释: Armstrong 推理规则是指一组推理规则,用于推断关系数据库的所有功能依赖关系。它由以下公理组成:
Axiom of Reflexivity:
This axiom states: if Y is a subset of X, then X determines Y
Axiom of Augmentation:
The axiom of augmentation, also known as a partial dependency,
states if X determines Y, then XZ determines YZ, for any Z
Axiom of Transitivity:
The axiom of transitivity says if X determines Y, and Y
determines Z, then X must also determine Z.
这个问题的测验