I've been curious about Spaces since first learning about them in some analytical class.
Here are a semi-random collection of notes about the concept.
Content here is:
guaranteed to be incomplete,
likely ambiguous/unclear if not wrong in places,
but it's a start ...
According to wikipedia, mathematics does not define the concept of space itself.
In general, however, Spaces consist of a set (also called a universe), with added structure.
A Set
is a collection of objects
The fundamental relationship between an object and a set
is that of membership.
If an object a is a member of set A,
a is said to be an element of A.
symbolized as: a ∈ A
A set can be defined:
by listing its elements, separated by commas,
or by defining some property (in braces {} ) that an element must have
in order to be a member of the set.
Defining a set by specifying a property must be done carefully,
because if choice of property is unrestricted,
it is possible to choose properties that will lead to paradoxes/contradictions,
such as Russel's paradox, that arises when using the property: the set of all sets not a member of themselves.
Set theory is complicated...
Set operations (between sets) include union, intersection, and complementation.
Structure is defined as ...
--------------------------------
Examples of Spaces...
Vector Space:
A vector space consists of a set of elements called vectors
There are two operations defined: vector addition, and scalar multiplication
There are 8 axioms that must be valid to be considered a "vector space."
vector addition is associative.
vector addition is commutative.
there exists an additive identity (zero vector: v + 0 = v)
there exists an additive inverse vector for every vector ( v + (-v) = 0 )
scalar multiplication is associative ( a (bV) = (ab)V )
there exists a multiplicative identity ( ie: 1 such that: 1v = v )
scalar multiplication is distributive across vector addition ( a ( U + V) = aU + aV ).
scalar addition is distributive across scalar-vector multiplication ( (a+b) V = aV + bV ).