Yes. the set of rational numbers is a countable set which can be generated from repeatedly taking countable union, countable intersection and countable complement, etc. Therefore, it is a Borel Set.
Yes, since the set of real numbers can be expressed as a countable union of closed sets.In fact if we're talking about subsets of the real numbers (R), then by definition R is in all sigma-algebras of R including the Borel sigma-algebra, and so is a Borel set.
An example is given here: http://en.wikipedia.org/wiki/Non-Borel_set Any set that is easy to think of will be a Borel set, so an example of a non-Borel set will be complicated. Another approach: All Borel sets are Lebesgue measurable. The axiom of choice can be used to give an example of a non-measurable set, and this set will also be a non-Borel set. See http://en.wikipedia.org/wiki/Non-measurable_set = =
The set of Rational Numbers is a [proper] subset of Real Numbers.
In the context of the rational numbers ( \mathbb{Q} ) with the standard topology induced by the real numbers ( \mathbb{R} ), a singleton set ( {q} ) (where ( q ) is a rational number) is not open because for any point ( q ) in ( \mathbb{Q} ), every open interval around ( q ) contains both rational and irrational numbers. Therefore, any interval ( (q - \epsilon, q + \epsilon) ) intersects with points outside the singleton set, meaning it cannot be entirely contained within ( {q} ). Thus, singleton sets do not satisfy the definition of an open set in ( \mathbb{Q} ).
What are equal sets?? A set is a grouping of numbers. Set P = {1,4,9} if set Q is equal it must contain exactly the same numbers.
A singleton point is a closed set. The natural numbers can be written as a countable union of points. Thus, they form a Borel set.
Yes, since the set of real numbers can be expressed as a countable union of closed sets.In fact if we're talking about subsets of the real numbers (R), then by definition R is in all sigma-algebras of R including the Borel sigma-algebra, and so is a Borel set.
No, it is not.
The set of rational numbers includes the set of natural numbers but they are not the same. All natural numbers are rational, not all rational numbers are natural.
Yes - the set of integers is a subset of the set of rational numbers.
The Real numbers
The derived set of a set of rational numbers is the set of all limit points of the original set. In other words, it includes all real numbers that can be approached arbitrarily closely by elements of the set. Since the rational numbers are dense in the real numbers, the derived set of a set of rational numbers is the set of all real numbers.
It is the rational numbers.
No. A real number is only one number whereas the set of rational numbers has infinitely many numbers. However, the set of real numbers does contain the set of rational numbers.
Both rational numbers and integers are subsets of the set of real numbers.
No; there are infinitely many rational numbers.
The set of rational numbers is the union of the set of fractional numbers and the set of whole numbers.