>>11677325sets are used as a foundation for almost all the math you know. one of the most basic things you can do is define the power set P(A) which gives you the set of all subsets of A. you could also introduce the notion of a ordered pair (eg (a,b) = { {a}, {a,b} }). with that, you can define the artesian product of sets (eg AxB), and with that you can define relations as subsets of the cartesian product (eg R in P(AxB)), and special types of relations that are injective and that have the property that aRb and cRb implies a == c means you got functions. and you know what a function is.
