4.集合
幂集
A = {a,b}
\[P(A) = \{\emptyset,{a},{b},{a,b} \}\]
对称差
Note
- 对称差不满足幂等律即
- \(A\oplus A \neq A \eq \emptyset\)
\[A \oplus B = (A-B) \cup (B-A) = (A\cup B) - (A\cap B)\]
绝对补
\[\sim A = E-A\]
A = {a,b}
Note