Mathematics I / Sets and Set-Builder Notation
Practice question · True or false

For any set AA, both A\emptyset \subseteq A and A\emptyset \in A hold.

Hints
  1. One is about inclusion, the other about membership.
  2. Is \emptyset listed among AA's elements?
Show the answer

False

Why

False. A\emptyset \subseteq A always holds, vacuously, since there is no element of \emptyset to find missing from AA. But A\emptyset \in A requires the empty set to be listed as a member, which is true only for sets that happen to contain it, such as {}\{\emptyset\}. Inclusion and membership are different relations.

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