Prove that every first countable space is second countable
Determine all topologies on a set X ={a,b,c}
Prove that a function f from a metric space X to a metric space Y is continuous if and only if the inverse image of any open subset of Y is open in X
Prove that the subspace.of a complete metric is complete if and only if it is closed
Give an example of two metric on R2 which are equivalent ,substantiate your claim