I was wondering about the difference between the following possible conditions on a given continuous map $f : X \rightarrow Y$ between topological spaces:
$f$ has discrete fibers
$f$ is a local homeomorphism
$f$ is a covering map.
As far as I know, 3 implies 1 and 2; however, I am wondering if there are any further implications between these three properties, or if there are counter-examples between them.
Would anyone have any suggestions as to where I can find proofs or counter-examples of these?