I was given in homework to formalize some statements regarding functions, but after a long while scanning wikipedia, I wasn't able to find how to start doing so, any help would be appreciated, will just give an example, I'll fill out the rest myself :)
example: There exists groups A, B so that every function from A to B is injective.
There exists f: A -> B so that f is injective but not surjective.
Hope it's understood, because I'm completely clueless...
EDIT: perhaps formal language wasn't an appropriate tag, but what I'm referring to is the "translation" of plain english to logical mathametical statements.