最近在自学离散数学,做到集合论部分的证明题时,如
证明:
,
我记得好像在书本上没有学过有关差集的运算法则啊。
遇事不决,马上百度。
原来书本(离散数学及其应用第二版,傅彦。。)上少了有关差集的法则。
补交转换律: A – B = A ∩
![\large \overline{B}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BB%7D)
全部运算法则( E 是全集,
![\large {\color{Red} {\color{Red} }\overline{A}}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%7B%5Ccolor%7BRed%7D%20%7B%5Ccolor%7BRed%7D%20%7D%5Coverline%7BA%7D%7D)
是补集 )
1. 交换律: A ∪ B = B∪A, A ∩ B = B ∩ A
2. 结合律: (A ∪ B) ∪ C = A ∪ (B∪C) = A ∪ B∪C
(A ∩ B) ∩ C = A ∩ (B ∩ C) = A ∩ B ∩ C
3. 分配律: (A ∩ B) ∪C = (A∪C) ∩ (B∪C)
(A∪B) ∩ C = (A ∩ C) ∪(B ∩ C)
4. 德摩根律:
![\large \overline{A\bigcup B }=\overline{A}\bigcap \overline{B}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BA%5Cbigcup%20B%20%7D%3D%5Coverline%7BA%7D%5Cbigcap%20%5Coverline%7BB%7D)
(A ∪ B)’ = A’ ∩ B’
![\large \overline{A\bigcap B}=\overline{A}\bigcup \overline{B}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BA%5Cbigcap%20B%7D%3D%5Coverline%7BA%7D%5Cbigcup%20%5Coverline%7BB%7D)
(绝对形式)
6. 吸收律: (A ∩ B) ∪ A = A (A ∪ B) ∩ A = A
7. 零律: A ∪ E = E , A ∩ E = A
8. 同一律: A ∪ Ø = A,A ∩ E= A , A ∪ E = E , A ∩ Ø = Ø
9. 矛盾律: A ∩
![\large \overline{A}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BA%7D)
= Ø
10.排中律: A ∪
![\large \overline{A}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BA%7D)
= E
11.余补律:
![\LARGE \overline{\o }](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5CLARGE%20%5Coverline%7B%5Co%20%7D)
= E ,
![\large \overline{E}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BE%7D)
= Ø
12.双重否定律:
![\large \overline{\overline{A}}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7B%5Coverline%7BA%7D%7D)
= A
13.补交转换律: A – B = A ∩
![\large \overline{B}](https://private.codecogs.com/gif.latex?%5Cfn_jvn%20%5Clarge%20%5Coverline%7BB%7D)
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