一、填空题
1设集合A,B,其中A={1,2,3},B={1,2},则A-B=____________________; ?(A)-?(B)=__________________________.
2.设有限集合A,|A|=n,则|?(A×A)|=__________________________.
3.设集合A={a,b},B={1,2},则从A到B的所有映射是_______________________________________,其中双射的是__________________________.
4.已知命题公式G=?(P?Q)∧R,则G的主析取范式是_______________________________
__________________________________________________________.
6设A、B为两个集合,A={1,2,4},B={3,4},则从A?B=_________________________;A?B=_________________________;A-B=_____________________.
7.设