It depends on the context... But in general, a space is a set (or class or collection of mathematical objects) with some special properties (e.g. it is equipped with certain operations which in turn satisfy certain requirements). In essense, it's the universe you're going to work in, hence the name.
#3
Swapnil
459
6
So, for example, a Boolean Space \mathcal{B} would be a set of two elements 0 and 1 equipped with two binary operations \lor and \land and an unary operation \lnot such that the usual axioms of associativity, commutativity, distributivity, etc hold. Right?
It is well known that a vector space always admits an algebraic (Hamel) basis. This is a theorem that follows from Zorn's lemma based on the Axiom of Choice (AC).
Now consider any specific instance of vector space. Since the AC axiom may or may not be included in the underlying set theory, might there be examples of vector spaces in which an Hamel basis actually doesn't exist ?