Q:
Let A,B≠0 and let f:A→B be an onto mapping. Then if A is countable then prove B is countable.
Printable View
Q:
Let A,B≠0 and let f:A→B be an onto mapping. Then if A is countable then prove B is countable.
This is one of the most important theorems in theory of cardinality of sets:Quote:
Originally Posted by jas_viru
.
Now any subset of a countable set is countable. Because\subset A,\; g(B)\text { is countable })
That means that.