I've been reading Carli Masimo book "Functional programming in Kotlin by tutorials" and there is a sentence not clear for me.
Not all categories have initial and terminal objects but, if they do, they are unique. In logic, the initial object has the name False and the terminal object True.
what the unique means? the category or the initial-terminal? IMO, just the pair is unique, but it's likely the obvious by their name's meaning. and i think we can put more elements into sets of category so we can't say that the category unique. But i'm not sure because category theory is a mess with me. Thanks and appreciate any help.
You are right. If a category has a terminal object, the terminal object is unique (up to isomorphism). Similarly, if a category has an initial object, the initial object is unique (again up to isomorphism).