A=B,they are not two sets...No definion,no right

or wrong.You are right,though I also is right.Complementary set is very important for a set.

所有跟帖： 

• A=B,they are semantically not two sets, but symbolically two set -皆兄弟也- ♂ (0 bytes) () 07/24/2010 postreply 11:37:48

• A和B指同一個集合，如果A=B；A和B指不同集合，如果A!=B。但A和B是不同符號。 -皆兄弟也- ♂ (0 bytes) () 07/24/2010 postreply 11:59:45