Wot exactly is a null set? i dont understand it. if anyone could explain that wuld be wikid.
it would depend on the context, but it is, generically, something that is zero.
It exists to make difference between "something" and "nothing". A set that contains something is like something and the null set is nothing (contains nothing)
No, that is not necessarily true. A null set, could be, as I suspect it will be in this case, a set of measure zero.
ok..maybe my english is not good enough.. what is that called: ø?
isn't it a null set? or an empy set?
that is the empty set. It is a null set in the sense that its cardinality is zero.
is there any other set, whiches cardinality is zero exept the empty set?
I don't think so
No, it, the empty set, is unique. But that doesnt' have any bearing on what a null set is until we see what situation we are dealing with.
For example.. the set of rationals and irrationals. rationals are a null set and wot bout irrationals?? Matt could u explain in dummy maths why rationals are a null set?
As I thought, a null set is one that has measure zero. Example: and countable subset of R (Eg the rationals): let x_i be an enumeration of the set, round each point x_i consider the interval e/2^i, then the measure of the set is less than the sum over i of e^2^i = e. e was arbitrary hence it has measure zero.
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