subsets of countable sets are countable
The definition of countable sets would not serve us well if it did not conform with our intuition about countable sets. So let us prove that countability is in a sense hereditary.
Every subset of a countable set is itself countable.
Let and countable with , a bijective function as in the definition of countable sets.
|Title||subsets of countable sets are countable|
|Date of creation||2013-03-22 15:45:56|
|Last modified on||2013-03-22 15:45:56|
|Last modified by||beke (12826)|