http://wikiless.i2p/wiki/Set_(mathematics)?lang=en
In mathematics , a set is a collection of different things [ 1 ] [ 2 ] [ 3 ] [ 4 ] ; the things are called elements or members of the set and are typically mathematical objects : numbers, symbols, points in space , lines , other geometric shapes , variables , functions , or even other sets. [ 5 ] [ 6 ] Mathematics typically does not define precisely what constitutes a "set" or "collection", because such a definition would have to be in...